r291418 - Add the diagnose_if attribute to clang.

George Burgess IV via cfe-commits cfe-commits at lists.llvm.org
Sun Jan 8 20:12:15 PST 2017


Author: gbiv
Date: Sun Jan  8 22:12:14 2017
New Revision: 291418

URL: http://llvm.org/viewvc/llvm-project?rev=291418&view=rev
Log:
Add the diagnose_if attribute to clang.

`diagnose_if` can be used to have clang emit either warnings or errors
for function calls that meet user-specified conditions. For example:

```
constexpr int foo(int a)
  __attribute__((diagnose_if(a > 10, "configurations with a > 10 are "
                                      "expensive.", "warning")));

int f1 = foo(9);
int f2 = foo(10); // warning: configuration with a > 10 are expensive.
int f3 = foo(f2);
```

It currently only emits diagnostics in cases where the condition is
guaranteed to always be true. So, the following code will emit no
warnings:

```
constexpr int bar(int a) {
  foo(a);
  return 0;
}

constexpr int i = bar(10);
```

We hope to support optionally emitting diagnostics for cases like that
(and emitting runtime checks) in the future.

Release notes will appear shortly. :)

Differential Revision: https://reviews.llvm.org/D27424

Added:
    cfe/trunk/test/Sema/diagnose_if.c
    cfe/trunk/test/SemaCXX/diagnose_if.cpp
Modified:
    cfe/trunk/include/clang/AST/Expr.h
    cfe/trunk/include/clang/Basic/Attr.td
    cfe/trunk/include/clang/Basic/AttrDocs.td
    cfe/trunk/include/clang/Basic/DiagnosticCommonKinds.td
    cfe/trunk/include/clang/Basic/DiagnosticGroups.td
    cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
    cfe/trunk/include/clang/Sema/Initialization.h
    cfe/trunk/include/clang/Sema/Overload.h
    cfe/trunk/include/clang/Sema/Sema.h
    cfe/trunk/lib/AST/ExprConstant.cpp
    cfe/trunk/lib/Sema/SemaDeclAttr.cpp
    cfe/trunk/lib/Sema/SemaExpr.cpp
    cfe/trunk/lib/Sema/SemaLookup.cpp
    cfe/trunk/lib/Sema/SemaOverload.cpp
    cfe/trunk/lib/Sema/SemaTemplateInstantiateDecl.cpp

Modified: cfe/trunk/include/clang/AST/Expr.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/AST/Expr.h?rev=291418&r1=291417&r2=291418&view=diff
==============================================================================
--- cfe/trunk/include/clang/AST/Expr.h (original)
+++ cfe/trunk/include/clang/AST/Expr.h Sun Jan  8 22:12:14 2017
@@ -651,7 +651,8 @@ public:
   /// constant.
   bool EvaluateWithSubstitution(APValue &Value, ASTContext &Ctx,
                                 const FunctionDecl *Callee,
-                                ArrayRef<const Expr*> Args) const;
+                                ArrayRef<const Expr*> Args,
+                                const Expr *This = nullptr) const;
 
   /// \brief If the current Expr is a pointer, this will try to statically
   /// determine the number of bytes available where the pointer is pointing.

Modified: cfe/trunk/include/clang/Basic/Attr.td
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/Attr.td?rev=291418&r1=291417&r2=291418&view=diff
==============================================================================
--- cfe/trunk/include/clang/Basic/Attr.td (original)
+++ cfe/trunk/include/clang/Basic/Attr.td Sun Jan  8 22:12:14 2017
@@ -140,12 +140,15 @@ class Argument<string name, bit optional
   bit Fake = fake;
 }
 
-class BoolArgument<string name, bit opt = 0> : Argument<name, opt>;
+class BoolArgument<string name, bit opt = 0, bit fake = 0> : Argument<name, opt,
+                                                                      fake>;
 class IdentifierArgument<string name, bit opt = 0> : Argument<name, opt>;
 class IntArgument<string name, bit opt = 0> : Argument<name, opt>;
 class StringArgument<string name, bit opt = 0> : Argument<name, opt>;
 class ExprArgument<string name, bit opt = 0> : Argument<name, opt>;
-class FunctionArgument<string name, bit opt = 0> : Argument<name, opt>;
+class FunctionArgument<string name, bit opt = 0, bit fake = 0> : Argument<name,
+                                                                          opt,
+                                                                          fake>;
 class TypeArgument<string name, bit opt = 0> : Argument<name, opt>;
 class UnsignedArgument<string name, bit opt = 0> : Argument<name, opt>;
 class VariadicUnsignedArgument<string name> : Argument<name, 1>;
@@ -1591,6 +1594,26 @@ def Unavailable : InheritableAttr {
   let Documentation = [Undocumented];
 }
 
+def DiagnoseIf : InheritableAttr {
+  let Spellings = [GNU<"diagnose_if">];
+  let Subjects = SubjectList<[Function]>;
+  let Args = [ExprArgument<"Cond">, StringArgument<"Message">,
+              EnumArgument<"DiagnosticType",
+                           "DiagnosticType",
+                           ["error", "warning"],
+                           ["DT_Error", "DT_Warning"]>,
+              BoolArgument<"ArgDependent", 0, /*fake*/ 1>,
+              FunctionArgument<"Parent", 0, /*fake*/ 1>];
+  let DuplicatesAllowedWhileMerging = 1;
+  let LateParsed = 1;
+  let AdditionalMembers = [{
+    bool isError() const { return diagnosticType == DT_Error; }
+    bool isWarning() const { return diagnosticType == DT_Warning; }
+  }];
+  let TemplateDependent = 1;
+  let Documentation = [DiagnoseIfDocs];
+}
+
 def ArcWeakrefUnavailable : InheritableAttr {
   let Spellings = [GNU<"objc_arc_weak_reference_unavailable">];
   let Subjects = SubjectList<[ObjCInterface], ErrorDiag>;

Modified: cfe/trunk/include/clang/Basic/AttrDocs.td
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/AttrDocs.td?rev=291418&r1=291417&r2=291418&view=diff
==============================================================================
--- cfe/trunk/include/clang/Basic/AttrDocs.td (original)
+++ cfe/trunk/include/clang/Basic/AttrDocs.td Sun Jan  8 22:12:14 2017
@@ -378,6 +378,65 @@ template instantiation, so the value for
   }];
 }
 
+def DiagnoseIfDocs : Documentation {
+  let Category = DocCatFunction;
+  let Content = [{
+The ``diagnose_if`` attribute can be placed on function declarations to emit
+warnings or errors at compile-time if calls to the attributed function meet
+certain user-defined criteria. For example:
+
+.. code-block:: c
+  void abs(int a)
+    __attribute__((diagnose_if(a >= 0, "Redundant abs call", "warning")));
+  void must_abs(int a)
+    __attribute__((diagnose_if(a >= 0, "Redundant abs call", "error")));
+
+  int val = abs(1); // warning: Redundant abs call
+  int val2 = must_abs(1); // error: Redundant abs call
+  int val3 = abs(val);
+  int val4 = must_abs(val); // Because run-time checks are not emitted for
+                            // diagnose_if attributes, this executes without
+                            // issue.
+
+
+``diagnose_if`` is closely related to ``enable_if``, with a few key differences:
+
+* Overload resolution is not aware of ``diagnose_if`` attributes: they're
+  considered only after we select the best candidate from a given candidate set.
+* Function declarations that differ only in their ``diagnose_if`` attributes are
+  considered to be redeclarations of the same function (not overloads).
+* If the condition provided to ``diagnose_if`` cannot be evaluated, no
+  diagnostic will be emitted.
+
+Otherwise, ``diagnose_if`` is essentially the logical negation of ``enable_if``.
+
+As a result of bullet number two, ``diagnose_if`` attributes will stack on the
+same function. For example:
+
+.. code-block:: c
+
+  int foo() __attribute__((diagnose_if(1, "diag1", "warning")));
+  int foo() __attribute__((diagnose_if(1, "diag2", "warning")));
+
+  int bar = foo(); // warning: diag1
+                   // warning: diag2
+  int (*fooptr)(void) = foo; // warning: diag1
+                             // warning: diag2
+
+  constexpr int supportsAPILevel(int N) { return N < 5; }
+  int baz(int a)
+    __attribute__((diagnose_if(!supportsAPILevel(10),
+                               "Upgrade to API level 10 to use baz", "error")));
+  int baz(int a)
+    __attribute__((diagnose_if(!a, "0 is not recommended.", "warning")));
+
+  int (*bazptr)(int) = baz; // error: Upgrade to API level 10 to use baz
+  int v = baz(0); // error: Upgrade to API level 10 to use baz
+
+Query for this feature with ``__has_attribute(diagnose_if)``.
+  }];
+}
+
 def PassObjectSizeDocs : Documentation {
   let Category = DocCatVariable; // Technically it's a parameter doc, but eh.
   let Content = [{

Modified: cfe/trunk/include/clang/Basic/DiagnosticCommonKinds.td
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticCommonKinds.td?rev=291418&r1=291417&r2=291418&view=diff
==============================================================================
--- cfe/trunk/include/clang/Basic/DiagnosticCommonKinds.td (original)
+++ cfe/trunk/include/clang/Basic/DiagnosticCommonKinds.td Sun Jan  8 22:12:14 2017
@@ -161,6 +161,8 @@ def ext_old_implicitly_unsigned_long_cxx
   InGroup<CXX11Compat>;
 def ext_clang_enable_if : Extension<"'enable_if' is a clang extension">,
                           InGroup<GccCompat>;
+def ext_clang_diagnose_if : Extension<"'diagnose_if' is a clang extension">,
+                            InGroup<GccCompat>;
 
 // SEH
 def err_seh_expected_handler : Error<

Modified: cfe/trunk/include/clang/Basic/DiagnosticGroups.td
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticGroups.td?rev=291418&r1=291417&r2=291418&view=diff
==============================================================================
--- cfe/trunk/include/clang/Basic/DiagnosticGroups.td (original)
+++ cfe/trunk/include/clang/Basic/DiagnosticGroups.td Sun Jan  8 22:12:14 2017
@@ -495,6 +495,7 @@ def UnusedPropertyIvar :  DiagGroup<"unu
 def UnusedGetterReturnValue : DiagGroup<"unused-getter-return-value">;
 def UsedButMarkedUnused : DiagGroup<"used-but-marked-unused">;
 def UserDefinedLiterals : DiagGroup<"user-defined-literals">;
+def UserDefinedWarnings : DiagGroup<"user-defined-warnings">;
 def Reorder : DiagGroup<"reorder">;
 def UndeclaredSelector : DiagGroup<"undeclared-selector">;
 def ImplicitAtomic : DiagGroup<"implicit-atomic-properties">;
@@ -683,7 +684,8 @@ def Most : DiagGroup<"most", [
     OverloadedVirtual,
     PrivateExtern,
     SelTypeCast,
-    ExternCCompat
+    ExternCCompat,
+    UserDefinedWarnings
  ]>;
 
 // Thread Safety warnings 

Modified: cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td?rev=291418&r1=291417&r2=291418&view=diff
==============================================================================
--- cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td (original)
+++ cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td Sun Jan  8 22:12:14 2017
@@ -2141,8 +2141,11 @@ def err_constexpr_local_var_no_init : Er
 def ext_constexpr_function_never_constant_expr : ExtWarn<
   "constexpr %select{function|constructor}0 never produces a "
   "constant expression">, InGroup<DiagGroup<"invalid-constexpr">>, DefaultError;
-def err_enable_if_never_constant_expr : Error<
-  "'enable_if' attribute expression never produces a constant expression">;
+def err_attr_cond_never_constant_expr : Error<
+  "%0 attribute expression never produces a constant expression">;
+def err_diagnose_if_invalid_diagnostic_type : Error<
+  "invalid diagnostic type for 'diagnose_if'; use \"error\" or \"warning\" "
+  "instead">;
 def err_constexpr_body_no_return : Error<
   "no return statement in constexpr function">;
 def err_constexpr_return_missing_expr : Error<
@@ -3369,7 +3372,9 @@ def note_ovl_candidate_disabled_by_enabl
 def note_ovl_candidate_has_pass_object_size_params: Note<
     "candidate address cannot be taken because parameter %0 has "
     "pass_object_size attribute">;
-def note_ovl_candidate_disabled_by_enable_if_attr : Note<
+def err_diagnose_if_succeeded : Error<"%0">;
+def warn_diagnose_if_succeeded : Warning<"%0">, InGroup<UserDefinedWarnings>;
+def note_ovl_candidate_disabled_by_function_cond_attr : Note<
     "candidate disabled: %0">;
 def note_ovl_candidate_disabled_by_extension : Note<
     "candidate disabled due to OpenCL extension">;
@@ -4398,6 +4403,7 @@ def note_not_found_by_two_phase_lookup :
 def err_undeclared_use : Error<"use of undeclared %0">;
 def warn_deprecated : Warning<"%0 is deprecated">,
     InGroup<DeprecatedDeclarations>;
+def note_from_diagnose_if : Note<"from 'diagnose_if' attribute on %0:">;
 def warn_property_method_deprecated :
     Warning<"property access is using %0 method which is deprecated">,
     InGroup<DeprecatedDeclarations>;

Modified: cfe/trunk/include/clang/Sema/Initialization.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Sema/Initialization.h?rev=291418&r1=291417&r2=291418&view=diff
==============================================================================
--- cfe/trunk/include/clang/Sema/Initialization.h (original)
+++ cfe/trunk/include/clang/Sema/Initialization.h Sun Jan  8 22:12:14 2017
@@ -215,14 +215,14 @@ public:
 
   /// \brief Create the initialization entity for a parameter.
   static InitializedEntity InitializeParameter(ASTContext &Context,
-                                               ParmVarDecl *Parm) {
+                                               const ParmVarDecl *Parm) {
     return InitializeParameter(Context, Parm, Parm->getType());
   }
 
   /// \brief Create the initialization entity for a parameter, but use
   /// another type.
   static InitializedEntity InitializeParameter(ASTContext &Context,
-                                               ParmVarDecl *Parm,
+                                               const ParmVarDecl *Parm,
                                                QualType Type) {
     bool Consumed = (Context.getLangOpts().ObjCAutoRefCount &&
                      Parm->hasAttr<NSConsumedAttr>());

Modified: cfe/trunk/include/clang/Sema/Overload.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Sema/Overload.h?rev=291418&r1=291417&r2=291418&view=diff
==============================================================================
--- cfe/trunk/include/clang/Sema/Overload.h (original)
+++ cfe/trunk/include/clang/Sema/Overload.h Sun Jan  8 22:12:14 2017
@@ -668,6 +668,26 @@ namespace clang {
     /// to be used while performing partial ordering of function templates.
     unsigned ExplicitCallArguments;
 
+    /// The number of diagnose_if attributes that this overload triggered.
+    /// If any of the triggered attributes are errors, this won't count
+    /// diagnose_if warnings.
+    unsigned NumTriggeredDiagnoseIfs = 0;
+
+    /// Basically a TinyPtrVector<DiagnoseIfAttr *> that doesn't own the vector:
+    /// If NumTriggeredDiagnoseIfs is 0 or 1, this is a DiagnoseIfAttr *,
+    /// otherwise it's a pointer to an array of `NumTriggeredDiagnoseIfs`
+    /// DiagnoseIfAttr *s.
+    llvm::PointerUnion<DiagnoseIfAttr *, DiagnoseIfAttr **> DiagnoseIfInfo;
+
+    /// Gets an ArrayRef for the data at DiagnoseIfInfo. Note that this may give
+    /// you a pointer into DiagnoseIfInfo.
+    ArrayRef<DiagnoseIfAttr *> getDiagnoseIfInfo() const {
+      auto *Ptr = NumTriggeredDiagnoseIfs <= 1
+                      ? DiagnoseIfInfo.getAddrOfPtr1()
+                      : DiagnoseIfInfo.get<DiagnoseIfAttr **>();
+      return {Ptr, NumTriggeredDiagnoseIfs};
+    }
+
     union {
       DeductionFailureInfo DeductionFailure;
       
@@ -732,17 +752,42 @@ namespace clang {
     SmallVector<OverloadCandidate, 16> Candidates;
     llvm::SmallPtrSet<Decl *, 16> Functions;
 
-    // Allocator for OverloadCandidate::Conversions. We store the first few
-    // elements inline to avoid allocation for small sets.
-    llvm::BumpPtrAllocator ConversionSequenceAllocator;
+    // Allocator for OverloadCandidate::Conversions and DiagnoseIfAttr* arrays.
+    // We store the first few of each of these inline to avoid allocation for
+    // small sets.
+    llvm::BumpPtrAllocator SlabAllocator;
 
     SourceLocation Loc;
     CandidateSetKind Kind;
 
-    unsigned NumInlineSequences;
-    llvm::AlignedCharArray<alignof(ImplicitConversionSequence),
-                           16 * sizeof(ImplicitConversionSequence)>
-        InlineSpace;
+    constexpr static unsigned NumInlineBytes =
+        24 * sizeof(ImplicitConversionSequence);
+    unsigned NumInlineBytesUsed;
+    llvm::AlignedCharArray<alignof(void *), NumInlineBytes> InlineSpace;
+
+    /// If we have space, allocates from inline storage. Otherwise, allocates
+    /// from the slab allocator.
+    /// FIXME: It would probably be nice to have a SmallBumpPtrAllocator
+    /// instead.
+    template <typename T>
+    T *slabAllocate(unsigned N) {
+      // It's simpler if this doesn't need to consider alignment.
+      static_assert(alignof(T) == alignof(void *),
+                    "Only works for pointer-aligned types.");
+      static_assert(std::is_trivial<T>::value ||
+                        std::is_same<ImplicitConversionSequence, T>::value,
+                    "Add destruction logic to OverloadCandidateSet::clear().");
+
+      unsigned NBytes = sizeof(T) * N;
+      if (NBytes > NumInlineBytes - NumInlineBytesUsed)
+        return SlabAllocator.Allocate<T>(N);
+      char *FreeSpaceStart = InlineSpace.buffer + NumInlineBytesUsed;
+      assert(uintptr_t(FreeSpaceStart) % alignof(void *) == 0 &&
+             "Misaligned storage!");
+
+      NumInlineBytesUsed += NBytes;
+      return reinterpret_cast<T *>(FreeSpaceStart);
+    }
 
     OverloadCandidateSet(const OverloadCandidateSet &) = delete;
     void operator=(const OverloadCandidateSet &) = delete;
@@ -751,12 +796,17 @@ namespace clang {
 
   public:
     OverloadCandidateSet(SourceLocation Loc, CandidateSetKind CSK)
-        : Loc(Loc), Kind(CSK), NumInlineSequences(0) {}
+        : Loc(Loc), Kind(CSK), NumInlineBytesUsed(0) {}
     ~OverloadCandidateSet() { destroyCandidates(); }
 
     SourceLocation getLocation() const { return Loc; }
     CandidateSetKind getKind() const { return Kind; }
 
+    /// Make a DiagnoseIfAttr* array in a block of memory that will live for
+    /// as long as this OverloadCandidateSet. Returns a pointer to the start
+    /// of that array.
+    DiagnoseIfAttr **addDiagnoseIfComplaints(ArrayRef<DiagnoseIfAttr *> CA);
+
     /// \brief Determine when this overload candidate will be new to the
     /// overload set.
     bool isNewCandidate(Decl *F) {
@@ -779,19 +829,7 @@ namespace clang {
       Candidates.push_back(OverloadCandidate());
       OverloadCandidate &C = Candidates.back();
 
-      // Assign space from the inline array if there are enough free slots
-      // available.
-      if (NumConversions + NumInlineSequences <= 16) {
-        ImplicitConversionSequence *I =
-            (ImplicitConversionSequence *)InlineSpace.buffer;
-        C.Conversions = &I[NumInlineSequences];
-        NumInlineSequences += NumConversions;
-      } else {
-        // Otherwise get memory from the allocator.
-        C.Conversions = ConversionSequenceAllocator
-                          .Allocate<ImplicitConversionSequence>(NumConversions);
-      }
-
+      C.Conversions = slabAllocate<ImplicitConversionSequence>(NumConversions);
       // Construct the new objects.
       for (unsigned i = 0; i != NumConversions; ++i)
         new (&C.Conversions[i]) ImplicitConversionSequence();

Modified: cfe/trunk/include/clang/Sema/Sema.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Sema/Sema.h?rev=291418&r1=291417&r2=291418&view=diff
==============================================================================
--- cfe/trunk/include/clang/Sema/Sema.h (original)
+++ cfe/trunk/include/clang/Sema/Sema.h Sun Jan  8 22:12:14 2017
@@ -2531,14 +2531,14 @@ public:
   void AddMethodCandidate(DeclAccessPair FoundDecl,
                           QualType ObjectType,
                           Expr::Classification ObjectClassification,
-                          ArrayRef<Expr *> Args,
+                          Expr *ThisArg, ArrayRef<Expr *> Args,
                           OverloadCandidateSet& CandidateSet,
                           bool SuppressUserConversion = false);
   void AddMethodCandidate(CXXMethodDecl *Method,
                           DeclAccessPair FoundDecl,
                           CXXRecordDecl *ActingContext, QualType ObjectType,
                           Expr::Classification ObjectClassification,
-                          ArrayRef<Expr *> Args,
+                          Expr *ThisArg, ArrayRef<Expr *> Args,
                           OverloadCandidateSet& CandidateSet,
                           bool SuppressUserConversions = false,
                           bool PartialOverloading = false);
@@ -2548,6 +2548,7 @@ public:
                                  TemplateArgumentListInfo *ExplicitTemplateArgs,
                                   QualType ObjectType,
                                   Expr::Classification ObjectClassification,
+                                  Expr *ThisArg,
                                   ArrayRef<Expr *> Args,
                                   OverloadCandidateSet& CandidateSet,
                                   bool SuppressUserConversions = false,
@@ -2611,6 +2612,38 @@ public:
   EnableIfAttr *CheckEnableIf(FunctionDecl *Function, ArrayRef<Expr *> Args,
                               bool MissingImplicitThis = false);
 
+  /// Check the diagnose_if attributes on the given function. Returns the
+  /// first succesful fatal attribute, or null if calling Function(Args) isn't
+  /// an error.
+  ///
+  /// This only considers ArgDependent DiagnoseIfAttrs.
+  ///
+  /// This will populate Nonfatal with all non-error DiagnoseIfAttrs that
+  /// succeed. If this function returns non-null, the contents of Nonfatal are
+  /// unspecified.
+  DiagnoseIfAttr *
+  checkArgDependentDiagnoseIf(FunctionDecl *Function, ArrayRef<Expr *> Args,
+                              SmallVectorImpl<DiagnoseIfAttr *> &Nonfatal,
+                              bool MissingImplicitThis = false,
+                              Expr *ThisArg = nullptr);
+
+  /// Check the diagnose_if expressions on the given function. Returns the
+  /// first succesful fatal attribute, or null if using Function isn't
+  /// an error.
+  ///
+  /// This ignores all ArgDependent DiagnoseIfAttrs.
+  ///
+  /// This will populate Nonfatal with all non-error DiagnoseIfAttrs that
+  /// succeed. If this function returns non-null, the contents of Nonfatal are
+  /// unspecified.
+  DiagnoseIfAttr *
+  checkArgIndependentDiagnoseIf(FunctionDecl *Function,
+                                SmallVectorImpl<DiagnoseIfAttr *> &Nonfatal);
+
+  /// Emits the diagnostic contained in the given DiagnoseIfAttr at Loc. Also
+  /// emits a note about the location of said attribute.
+  void emitDiagnoseIfDiagnostic(SourceLocation Loc, const DiagnoseIfAttr *DIA);
+
   /// Returns whether the given function's address can be taken or not,
   /// optionally emitting a diagnostic if the address can't be taken.
   ///

Modified: cfe/trunk/lib/AST/ExprConstant.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/ExprConstant.cpp?rev=291418&r1=291417&r2=291418&view=diff
==============================================================================
--- cfe/trunk/lib/AST/ExprConstant.cpp (original)
+++ cfe/trunk/lib/AST/ExprConstant.cpp Sun Jan  8 22:12:14 2017
@@ -10410,10 +10410,25 @@ bool Expr::isCXX11ConstantExpr(const AST
 
 bool Expr::EvaluateWithSubstitution(APValue &Value, ASTContext &Ctx,
                                     const FunctionDecl *Callee,
-                                    ArrayRef<const Expr*> Args) const {
+                                    ArrayRef<const Expr*> Args,
+                                    const Expr *This) const {
   Expr::EvalStatus Status;
   EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantExpressionUnevaluated);
 
+  LValue ThisVal;
+  const LValue *ThisPtr = nullptr;
+  if (This) {
+#ifndef NDEBUG
+    auto *MD = dyn_cast<CXXMethodDecl>(Callee);
+    assert(MD && "Don't provide `this` for non-methods.");
+    assert(!MD->isStatic() && "Don't provide `this` for static methods.");
+#endif
+    if (EvaluateObjectArgument(Info, This, ThisVal))
+      ThisPtr = &ThisVal;
+    if (Info.EvalStatus.HasSideEffects)
+      return false;
+  }
+
   ArgVector ArgValues(Args.size());
   for (ArrayRef<const Expr*>::iterator I = Args.begin(), E = Args.end();
        I != E; ++I) {
@@ -10426,7 +10441,7 @@ bool Expr::EvaluateWithSubstitution(APVa
   }
 
   // Build fake call to Callee.
-  CallStackFrame Frame(Info, Callee->getLocation(), Callee, /*This*/nullptr,
+  CallStackFrame Frame(Info, Callee->getLocation(), Callee, ThisPtr,
                        ArgValues.data());
   return Evaluate(Value, Info, this) && !Info.EvalStatus.HasSideEffects;
 }

Modified: cfe/trunk/lib/Sema/SemaDeclAttr.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaDeclAttr.cpp?rev=291418&r1=291417&r2=291418&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaDeclAttr.cpp (original)
+++ cfe/trunk/lib/Sema/SemaDeclAttr.cpp Sun Jan  8 22:12:14 2017
@@ -32,6 +32,7 @@
 #include "clang/Sema/Lookup.h"
 #include "clang/Sema/Scope.h"
 #include "clang/Sema/SemaInternal.h"
+#include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/Support/MathExtras.h"
 
@@ -890,34 +891,117 @@ static void handleLocksExcludedAttr(Sema
                                Attr.getAttributeSpellingListIndex()));
 }
 
-static void handleEnableIfAttr(Sema &S, Decl *D, const AttributeList &Attr) {
-  S.Diag(Attr.getLoc(), diag::ext_clang_enable_if);
-
-  Expr *Cond = Attr.getArgAsExpr(0);
+static bool checkFunctionConditionAttr(Sema &S, Decl *D,
+                                       const AttributeList &Attr,
+                                       Expr *&Cond, StringRef &Msg) {
+  Cond = Attr.getArgAsExpr(0);
   if (!Cond->isTypeDependent()) {
     ExprResult Converted = S.PerformContextuallyConvertToBool(Cond);
     if (Converted.isInvalid())
-      return;
+      return false;
     Cond = Converted.get();
   }
 
-  StringRef Msg;
   if (!S.checkStringLiteralArgumentAttr(Attr, 1, Msg))
-    return;
+    return false;
+
+  if (Msg.empty())
+    Msg = "<no message provided>";
 
   SmallVector<PartialDiagnosticAt, 8> Diags;
   if (!Cond->isValueDependent() &&
       !Expr::isPotentialConstantExprUnevaluated(Cond, cast<FunctionDecl>(D),
                                                 Diags)) {
-    S.Diag(Attr.getLoc(), diag::err_enable_if_never_constant_expr);
+    S.Diag(Attr.getLoc(), diag::err_attr_cond_never_constant_expr)
+        << Attr.getName();
     for (const PartialDiagnosticAt &PDiag : Diags)
       S.Diag(PDiag.first, PDiag.second);
+    return false;
+  }
+  return true;
+}
+
+static void handleEnableIfAttr(Sema &S, Decl *D, const AttributeList &Attr) {
+  S.Diag(Attr.getLoc(), diag::ext_clang_enable_if);
+
+  Expr *Cond;
+  StringRef Msg;
+  if (checkFunctionConditionAttr(S, D, Attr, Cond, Msg))
+    D->addAttr(::new (S.Context)
+                   EnableIfAttr(Attr.getRange(), S.Context, Cond, Msg,
+                                Attr.getAttributeSpellingListIndex()));
+}
+
+namespace {
+/// Determines if a given Expr references any of the given function's
+/// ParmVarDecls, or the function's implicit `this` parameter (if applicable).
+class ArgumentDependenceChecker
+    : public RecursiveASTVisitor<ArgumentDependenceChecker> {
+#ifndef NDEBUG
+  const CXXRecordDecl *ClassType;
+#endif
+  llvm::SmallPtrSet<const ParmVarDecl *, 16> Parms;
+  bool Result;
+
+public:
+  ArgumentDependenceChecker(const FunctionDecl *FD) {
+#ifndef NDEBUG
+    if (const auto *MD = dyn_cast<CXXMethodDecl>(FD))
+      ClassType = MD->getParent();
+    else
+      ClassType = nullptr;
+#endif
+    Parms.insert(FD->param_begin(), FD->param_end());
+  }
+
+  bool referencesArgs(Expr *E) {
+    Result = false;
+    TraverseStmt(E);
+    return Result;
+  }
+
+  bool VisitCXXThisExpr(CXXThisExpr *E) {
+    assert(E->getType()->getPointeeCXXRecordDecl() == ClassType &&
+           "`this` doesn't refer to the enclosing class?");
+    Result = true;
+    return false;
+  }
+
+  bool VisitDeclRefExpr(DeclRefExpr *DRE) {
+    if (const auto *PVD = dyn_cast<ParmVarDecl>(DRE->getDecl()))
+      if (Parms.count(PVD)) {
+        Result = true;
+        return false;
+      }
+    return true;
+  }
+};
+}
+
+static void handleDiagnoseIfAttr(Sema &S, Decl *D, const AttributeList &Attr) {
+  S.Diag(Attr.getLoc(), diag::ext_clang_diagnose_if);
+
+  Expr *Cond;
+  StringRef Msg;
+  if (!checkFunctionConditionAttr(S, D, Attr, Cond, Msg))
+    return;
+
+  StringRef DiagTypeStr;
+  if (!S.checkStringLiteralArgumentAttr(Attr, 2, DiagTypeStr))
+    return;
+
+  DiagnoseIfAttr::DiagnosticType DiagType;
+  if (!DiagnoseIfAttr::ConvertStrToDiagnosticType(DiagTypeStr, DiagType)) {
+    S.Diag(Attr.getArgAsExpr(2)->getLocStart(),
+           diag::err_diagnose_if_invalid_diagnostic_type);
     return;
   }
 
-  D->addAttr(::new (S.Context)
-             EnableIfAttr(Attr.getRange(), S.Context, Cond, Msg,
-                          Attr.getAttributeSpellingListIndex()));
+  auto *FD = cast<FunctionDecl>(D);
+  bool ArgDependent = ArgumentDependenceChecker(FD).referencesArgs(Cond);
+  D->addAttr(::new (S.Context) DiagnoseIfAttr(
+      Attr.getRange(), S.Context, Cond, Msg, DiagType, ArgDependent, FD,
+      Attr.getAttributeSpellingListIndex()));
 }
 
 static void handlePassObjectSizeAttr(Sema &S, Decl *D,
@@ -5682,6 +5766,9 @@ static void ProcessDeclAttribute(Sema &S
   case AttributeList::AT_EnableIf:
     handleEnableIfAttr(S, D, Attr);
     break;
+  case AttributeList::AT_DiagnoseIf:
+    handleDiagnoseIfAttr(S, D, Attr);
+    break;
   case AttributeList::AT_ExtVectorType:
     handleExtVectorTypeAttr(S, scope, D, Attr);
     break;

Modified: cfe/trunk/lib/Sema/SemaExpr.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaExpr.cpp?rev=291418&r1=291417&r2=291418&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaExpr.cpp (original)
+++ cfe/trunk/lib/Sema/SemaExpr.cpp Sun Jan  8 22:12:14 2017
@@ -342,6 +342,7 @@ bool Sema::DiagnoseUseOfDecl(NamedDecl *
   }
 
   // See if this is a deleted function.
+  SmallVector<DiagnoseIfAttr *, 4> DiagnoseIfWarnings;
   if (FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
     if (FD->isDeleted()) {
       auto *Ctor = dyn_cast<CXXConstructorDecl>(FD);
@@ -363,6 +364,12 @@ bool Sema::DiagnoseUseOfDecl(NamedDecl *
 
     if (getLangOpts().CUDA && !CheckCUDACall(Loc, FD))
       return true;
+
+    if (const DiagnoseIfAttr *A =
+            checkArgIndependentDiagnoseIf(FD, DiagnoseIfWarnings)) {
+      emitDiagnoseIfDiagnostic(Loc, A);
+      return true;
+    }
   }
 
   // [OpenMP 4.0], 2.15 declare reduction Directive, Restrictions
@@ -377,6 +384,10 @@ bool Sema::DiagnoseUseOfDecl(NamedDecl *
     Diag(D->getLocation(), diag::note_entity_declared_at) << D;
     return true;
   }
+
+  for (const auto *W : DiagnoseIfWarnings)
+    emitDiagnoseIfDiagnostic(Loc, W);
+
   DiagnoseAvailabilityOfDecl(*this, D, Loc, UnknownObjCClass,
                              ObjCPropertyAccess);
 
@@ -5154,12 +5165,40 @@ static FunctionDecl *rewriteBuiltinFunct
   return OverloadDecl;
 }
 
-static bool isNumberOfArgsValidForCall(Sema &S, const FunctionDecl *Callee,
-                                       std::size_t NumArgs) {
-  if (S.TooManyArguments(Callee->getNumParams(), NumArgs,
-                         /*PartialOverloading=*/false))
-    return Callee->isVariadic();
-  return Callee->getMinRequiredArguments() <= NumArgs;
+static void checkDirectCallValidity(Sema &S, const Expr *Fn,
+                                    FunctionDecl *Callee,
+                                    MultiExprArg ArgExprs) {
+  // `Callee` (when called with ArgExprs) may be ill-formed. enable_if (and
+  // similar attributes) really don't like it when functions are called with an
+  // invalid number of args.
+  if (S.TooManyArguments(Callee->getNumParams(), ArgExprs.size(),
+                         /*PartialOverloading=*/false) &&
+      !Callee->isVariadic())
+    return;
+  if (Callee->getMinRequiredArguments() > ArgExprs.size())
+    return;
+
+  if (const EnableIfAttr *Attr = S.CheckEnableIf(Callee, ArgExprs, true)) {
+    S.Diag(Fn->getLocStart(),
+           isa<CXXMethodDecl>(Callee)
+               ? diag::err_ovl_no_viable_member_function_in_call
+               : diag::err_ovl_no_viable_function_in_call)
+        << Callee << Callee->getSourceRange();
+    S.Diag(Callee->getLocation(),
+           diag::note_ovl_candidate_disabled_by_function_cond_attr)
+        << Attr->getCond()->getSourceRange() << Attr->getMessage();
+    return;
+  }
+
+  SmallVector<DiagnoseIfAttr *, 4> Nonfatal;
+  if (const DiagnoseIfAttr *Attr = S.checkArgDependentDiagnoseIf(
+          Callee, ArgExprs, Nonfatal, /*MissingImplicitThis=*/true)) {
+    S.emitDiagnoseIfDiagnostic(Fn->getLocStart(), Attr);
+    return;
+  }
+
+  for (const auto *W : Nonfatal)
+    S.emitDiagnoseIfDiagnostic(Fn->getLocStart(), W);
 }
 
 /// ActOnCallExpr - Handle a call to Fn with the specified array of arguments.
@@ -5294,26 +5333,8 @@ ExprResult Sema::ActOnCallExpr(Scope *Sc
 
     if (getLangOpts().OpenCL && checkOpenCLDisabledDecl(*FD, *Fn))
       return ExprError();
-    
-    // CheckEnableIf assumes that the we're passing in a sane number of args for
-    // FD, but that doesn't always hold true here. This is because, in some
-    // cases, we'll emit a diag about an ill-formed function call, but then
-    // we'll continue on as if the function call wasn't ill-formed. So, if the
-    // number of args looks incorrect, don't do enable_if checks; we should've
-    // already emitted an error about the bad call.
-    if (FD->hasAttr<EnableIfAttr>() &&
-        isNumberOfArgsValidForCall(*this, FD, ArgExprs.size())) {
-      if (const EnableIfAttr *Attr = CheckEnableIf(FD, ArgExprs, true)) {
-        Diag(Fn->getLocStart(),
-             isa<CXXMethodDecl>(FD)
-                 ? diag::err_ovl_no_viable_member_function_in_call
-                 : diag::err_ovl_no_viable_function_in_call)
-            << FD << FD->getSourceRange();
-        Diag(FD->getLocation(),
-             diag::note_ovl_candidate_disabled_by_enable_if_attr)
-            << Attr->getCond()->getSourceRange() << Attr->getMessage();
-      }
-    }
+
+    checkDirectCallValidity(*this, Fn, FD, ArgExprs);
   }
 
   return BuildResolvedCallExpr(Fn, NDecl, LParenLoc, ArgExprs, RParenLoc,

Modified: cfe/trunk/lib/Sema/SemaLookup.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaLookup.cpp?rev=291418&r1=291417&r2=291418&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaLookup.cpp (original)
+++ cfe/trunk/lib/Sema/SemaLookup.cpp Sun Jan  8 22:12:14 2017
@@ -2960,6 +2960,7 @@ Sema::SpecialMemberOverloadResult *Sema:
     if (CXXMethodDecl *M = dyn_cast<CXXMethodDecl>(Cand->getUnderlyingDecl())) {
       if (SM == CXXCopyAssignment || SM == CXXMoveAssignment)
         AddMethodCandidate(M, Cand, RD, ThisTy, Classification,
+                           /*ThisArg=*/nullptr,
                            llvm::makeArrayRef(&Arg, NumArgs), OCS, true);
       else if (CtorInfo)
         AddOverloadCandidate(CtorInfo.Constructor, CtorInfo.FoundDecl,
@@ -2972,7 +2973,7 @@ Sema::SpecialMemberOverloadResult *Sema:
       if (SM == CXXCopyAssignment || SM == CXXMoveAssignment)
         AddMethodTemplateCandidate(
             Tmpl, Cand, RD, nullptr, ThisTy, Classification,
-            llvm::makeArrayRef(&Arg, NumArgs), OCS, true);
+            /*ThisArg=*/nullptr, llvm::makeArrayRef(&Arg, NumArgs), OCS, true);
       else if (CtorInfo)
         AddTemplateOverloadCandidate(
             CtorInfo.ConstructorTmpl, CtorInfo.FoundDecl, nullptr,

Modified: cfe/trunk/lib/Sema/SemaOverload.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaOverload.cpp?rev=291418&r1=291417&r2=291418&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaOverload.cpp (original)
+++ cfe/trunk/lib/Sema/SemaOverload.cpp Sun Jan  8 22:12:14 2017
@@ -29,6 +29,7 @@
 #include "clang/Sema/Template.h"
 #include "clang/Sema/TemplateDeduction.h"
 #include "llvm/ADT/DenseSet.h"
+#include "llvm/ADT/Optional.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/SmallString.h"
@@ -830,12 +831,20 @@ void OverloadCandidateSet::destroyCandid
 
 void OverloadCandidateSet::clear() {
   destroyCandidates();
-  ConversionSequenceAllocator.Reset();
-  NumInlineSequences = 0;
+  // DiagnoseIfAttrs are just pointers, so we don't need to destroy them.
+  SlabAllocator.Reset();
+  NumInlineBytesUsed = 0;
   Candidates.clear();
   Functions.clear();
 }
 
+DiagnoseIfAttr **
+OverloadCandidateSet::addDiagnoseIfComplaints(ArrayRef<DiagnoseIfAttr *> CA) {
+  auto *DIA = slabAllocate<DiagnoseIfAttr *>(CA.size());
+  std::uninitialized_copy(CA.begin(), CA.end(), DIA);
+  return DIA;
+}
+
 namespace {
   class UnbridgedCastsSet {
     struct Entry {
@@ -5814,6 +5823,28 @@ static bool IsAcceptableNonMemberOperato
   return false;
 }
 
+static void initDiagnoseIfComplaint(Sema &S, OverloadCandidateSet &CandidateSet,
+                                    OverloadCandidate &Candidate,
+                                    FunctionDecl *Function,
+                                    ArrayRef<Expr *> Args,
+                                    bool MissingImplicitThis = false,
+                                    Expr *ExplicitThis = nullptr) {
+  SmallVector<DiagnoseIfAttr *, 8> Results;
+  if (DiagnoseIfAttr *DIA = S.checkArgDependentDiagnoseIf(
+          Function, Args, Results, MissingImplicitThis, ExplicitThis)) {
+    Results.clear();
+    Results.push_back(DIA);
+  }
+
+  Candidate.NumTriggeredDiagnoseIfs = Results.size();
+  if (Results.empty())
+    Candidate.DiagnoseIfInfo = nullptr;
+  else if (Results.size() == 1)
+    Candidate.DiagnoseIfInfo = Results[0];
+  else
+    Candidate.DiagnoseIfInfo = CandidateSet.addDiagnoseIfComplaints(Results);
+}
+
 /// AddOverloadCandidate - Adds the given function to the set of
 /// candidate functions, using the given function call arguments.  If
 /// @p SuppressUserConversions, then don't allow user-defined
@@ -5847,8 +5878,8 @@ Sema::AddOverloadCandidate(FunctionDecl
       // is irrelevant.
       AddMethodCandidate(Method, FoundDecl, Method->getParent(),
                          QualType(), Expr::Classification::makeSimpleLValue(),
-                         Args, CandidateSet, SuppressUserConversions,
-                         PartialOverloading);
+                         /*ThisArg=*/nullptr, Args, CandidateSet,
+                         SuppressUserConversions, PartialOverloading);
       return;
     }
     // We treat a constructor like a non-member function, since its object
@@ -6008,6 +6039,8 @@ Sema::AddOverloadCandidate(FunctionDecl
     Candidate.FailureKind = ovl_fail_ext_disabled;
     return;
   }
+
+  initDiagnoseIfComplaint(*this, CandidateSet, Candidate, Function, Args);
 }
 
 ObjCMethodDecl *
@@ -6120,66 +6153,87 @@ getOrderedEnableIfAttrs(const FunctionDe
   return Result;
 }
 
-EnableIfAttr *Sema::CheckEnableIf(FunctionDecl *Function, ArrayRef<Expr *> Args,
-                                  bool MissingImplicitThis) {
-  auto EnableIfAttrs = getOrderedEnableIfAttrs(Function);
-  if (EnableIfAttrs.empty())
-    return nullptr;
-
-  SFINAETrap Trap(*this);
-  SmallVector<Expr *, 16> ConvertedArgs;
-  bool InitializationFailed = false;
+static bool
+convertArgsForAvailabilityChecks(Sema &S, FunctionDecl *Function, Expr *ThisArg,
+                                 ArrayRef<Expr *> Args, Sema::SFINAETrap &Trap,
+                                 bool MissingImplicitThis, Expr *&ConvertedThis,
+                                 SmallVectorImpl<Expr *> &ConvertedArgs) {
+  if (ThisArg) {
+    CXXMethodDecl *Method = cast<CXXMethodDecl>(Function);
+    assert(!isa<CXXConstructorDecl>(Method) &&
+           "Shouldn't have `this` for ctors!");
+    assert(!Method->isStatic() && "Shouldn't have `this` for static methods!");
+    ExprResult R = S.PerformObjectArgumentInitialization(
+        ThisArg, /*Qualifier=*/nullptr, Method, Method);
+    if (R.isInvalid())
+      return false;
+    ConvertedThis = R.get();
+  } else {
+    if (auto *MD = dyn_cast<CXXMethodDecl>(Function)) {
+      (void)MD;
+      assert((MissingImplicitThis || MD->isStatic() ||
+              isa<CXXConstructorDecl>(MD)) &&
+             "Expected `this` for non-ctor instance methods");
+    }
+    ConvertedThis = nullptr;
+  }
 
   // Ignore any variadic arguments. Converting them is pointless, since the
-  // user can't refer to them in the enable_if condition.
+  // user can't refer to them in the function condition.
   unsigned ArgSizeNoVarargs = std::min(Function->param_size(), Args.size());
 
   // Convert the arguments.
   for (unsigned I = 0; I != ArgSizeNoVarargs; ++I) {
     ExprResult R;
-    if (I == 0 && !MissingImplicitThis && isa<CXXMethodDecl>(Function) &&
-        !cast<CXXMethodDecl>(Function)->isStatic() &&
-        !isa<CXXConstructorDecl>(Function)) {
-      CXXMethodDecl *Method = cast<CXXMethodDecl>(Function);
-      R = PerformObjectArgumentInitialization(Args[0], /*Qualifier=*/nullptr,
-                                              Method, Method);
-    } else {
-      R = PerformCopyInitialization(InitializedEntity::InitializeParameter(
-                                        Context, Function->getParamDecl(I)),
+    R = S.PerformCopyInitialization(InitializedEntity::InitializeParameter(
+                                        S.Context, Function->getParamDecl(I)),
                                     SourceLocation(), Args[I]);
-    }
 
-    if (R.isInvalid()) {
-      InitializationFailed = true;
-      break;
-    }
+    if (R.isInvalid())
+      return false;
 
     ConvertedArgs.push_back(R.get());
   }
 
-  if (InitializationFailed || Trap.hasErrorOccurred())
-    return EnableIfAttrs[0];
+  if (Trap.hasErrorOccurred())
+    return false;
 
   // Push default arguments if needed.
   if (!Function->isVariadic() && Args.size() < Function->getNumParams()) {
     for (unsigned i = Args.size(), e = Function->getNumParams(); i != e; ++i) {
       ParmVarDecl *P = Function->getParamDecl(i);
-      ExprResult R = PerformCopyInitialization(
-          InitializedEntity::InitializeParameter(Context,
+      ExprResult R = S.PerformCopyInitialization(
+          InitializedEntity::InitializeParameter(S.Context,
                                                  Function->getParamDecl(i)),
           SourceLocation(),
           P->hasUninstantiatedDefaultArg() ? P->getUninstantiatedDefaultArg()
                                            : P->getDefaultArg());
-      if (R.isInvalid()) {
-        InitializationFailed = true;
-        break;
-      }
+      if (R.isInvalid())
+        return false;
       ConvertedArgs.push_back(R.get());
     }
 
-    if (InitializationFailed || Trap.hasErrorOccurred())
-      return EnableIfAttrs[0];
+    if (Trap.hasErrorOccurred())
+      return false;
   }
+  return true;
+}
+
+EnableIfAttr *Sema::CheckEnableIf(FunctionDecl *Function, ArrayRef<Expr *> Args,
+                                  bool MissingImplicitThis) {
+  SmallVector<EnableIfAttr *, 4> EnableIfAttrs =
+      getOrderedEnableIfAttrs(Function);
+  if (EnableIfAttrs.empty())
+    return nullptr;
+
+  SFINAETrap Trap(*this);
+  SmallVector<Expr *, 16> ConvertedArgs;
+  // FIXME: We should look into making enable_if late-parsed.
+  Expr *DiscardedThis;
+  if (!convertArgsForAvailabilityChecks(
+          *this, Function, /*ThisArg=*/nullptr, Args, Trap,
+          /*MissingImplicitThis=*/true, DiscardedThis, ConvertedArgs))
+    return EnableIfAttrs[0];
 
   for (auto *EIA : EnableIfAttrs) {
     APValue Result;
@@ -6195,6 +6249,87 @@ EnableIfAttr *Sema::CheckEnableIf(Functi
   return nullptr;
 }
 
+static bool gatherDiagnoseIfAttrs(FunctionDecl *Function, bool ArgDependent,
+                                  SmallVectorImpl<DiagnoseIfAttr *> &Errors,
+                                  SmallVectorImpl<DiagnoseIfAttr *> &Nonfatal) {
+  for (auto *DIA : Function->specific_attrs<DiagnoseIfAttr>())
+    if (ArgDependent == DIA->getArgDependent()) {
+      if (DIA->isError())
+        Errors.push_back(DIA);
+      else
+        Nonfatal.push_back(DIA);
+    }
+
+  return !Errors.empty() || !Nonfatal.empty();
+}
+
+template <typename CheckFn>
+static DiagnoseIfAttr *
+checkDiagnoseIfAttrsWith(const SmallVectorImpl<DiagnoseIfAttr *> &Errors,
+                         SmallVectorImpl<DiagnoseIfAttr *> &Nonfatal,
+                         CheckFn &&IsSuccessful) {
+  // Note that diagnose_if attributes are late-parsed, so they appear in the
+  // correct order (unlike enable_if attributes).
+  auto ErrAttr = llvm::find_if(Errors, IsSuccessful);
+  if (ErrAttr != Errors.end())
+    return *ErrAttr;
+
+  llvm::erase_if(Nonfatal, [&](DiagnoseIfAttr *A) { return !IsSuccessful(A); });
+  return nullptr;
+}
+
+DiagnoseIfAttr *
+Sema::checkArgDependentDiagnoseIf(FunctionDecl *Function, ArrayRef<Expr *> Args,
+                                  SmallVectorImpl<DiagnoseIfAttr *> &Nonfatal,
+                                  bool MissingImplicitThis,
+                                  Expr *ThisArg) {
+  SmallVector<DiagnoseIfAttr *, 4> Errors;
+  if (!gatherDiagnoseIfAttrs(Function, /*ArgDependent=*/true, Errors, Nonfatal))
+    return nullptr;
+
+  SFINAETrap Trap(*this);
+  SmallVector<Expr *, 16> ConvertedArgs;
+  Expr *ConvertedThis;
+  if (!convertArgsForAvailabilityChecks(*this, Function, ThisArg, Args, Trap,
+                                        MissingImplicitThis, ConvertedThis,
+                                        ConvertedArgs))
+    return nullptr;
+
+  return checkDiagnoseIfAttrsWith(Errors, Nonfatal, [&](DiagnoseIfAttr *DIA) {
+    APValue Result;
+    // It's sane to use the same ConvertedArgs for any redecl of this function,
+    // since EvaluateWithSubstitution only cares about the position of each
+    // argument in the arg list, not the ParmVarDecl* it maps to.
+    if (!DIA->getCond()->EvaluateWithSubstitution(
+            Result, Context, DIA->getParent(), ConvertedArgs, ConvertedThis))
+      return false;
+    return Result.isInt() && Result.getInt().getBoolValue();
+  });
+}
+
+DiagnoseIfAttr *Sema::checkArgIndependentDiagnoseIf(
+    FunctionDecl *Function, SmallVectorImpl<DiagnoseIfAttr *> &Nonfatal) {
+  SmallVector<DiagnoseIfAttr *, 4> Errors;
+  if (!gatherDiagnoseIfAttrs(Function, /*ArgDependent=*/false, Errors,
+                             Nonfatal))
+    return nullptr;
+
+  return checkDiagnoseIfAttrsWith(Errors, Nonfatal, [&](DiagnoseIfAttr *DIA) {
+    bool Result;
+    return DIA->getCond()->EvaluateAsBooleanCondition(Result, Context) &&
+           Result;
+  });
+}
+
+void Sema::emitDiagnoseIfDiagnostic(SourceLocation Loc,
+                                    const DiagnoseIfAttr *DIA) {
+  auto Code = DIA->isError() ? diag::err_diagnose_if_succeeded
+                             : diag::warn_diagnose_if_succeeded;
+  Diag(Loc, Code) << DIA->getMessage();
+  Diag(DIA->getLocation(), diag::note_from_diagnose_if)
+      << DIA->getParent() << DIA->getCond()->getSourceRange();
+}
+
 /// \brief Add all of the function declarations in the given function set to
 /// the overload candidate set.
 void Sema::AddFunctionCandidates(const UnresolvedSetImpl &Fns,
@@ -6210,7 +6345,7 @@ void Sema::AddFunctionCandidates(const U
         AddMethodCandidate(cast<CXXMethodDecl>(FD), F.getPair(),
                            cast<CXXMethodDecl>(FD)->getParent(),
                            Args[0]->getType(), Args[0]->Classify(Context),
-                           Args.slice(1), CandidateSet,
+                           Args[0], Args.slice(1), CandidateSet,
                            SuppressUserConversions, PartialOverloading);
       else
         AddOverloadCandidate(FD, F.getPair(), Args, CandidateSet,
@@ -6219,13 +6354,12 @@ void Sema::AddFunctionCandidates(const U
       FunctionTemplateDecl *FunTmpl = cast<FunctionTemplateDecl>(D);
       if (isa<CXXMethodDecl>(FunTmpl->getTemplatedDecl()) &&
           !cast<CXXMethodDecl>(FunTmpl->getTemplatedDecl())->isStatic())
-        AddMethodTemplateCandidate(FunTmpl, F.getPair(),
-                              cast<CXXRecordDecl>(FunTmpl->getDeclContext()),
-                                   ExplicitTemplateArgs,
-                                   Args[0]->getType(),
-                                   Args[0]->Classify(Context), Args.slice(1),
-                                   CandidateSet, SuppressUserConversions,
-                                   PartialOverloading);
+        AddMethodTemplateCandidate(
+            FunTmpl, F.getPair(),
+            cast<CXXRecordDecl>(FunTmpl->getDeclContext()),
+            ExplicitTemplateArgs, Args[0]->getType(),
+            Args[0]->Classify(Context), Args[0], Args.slice(1), CandidateSet,
+            SuppressUserConversions, PartialOverloading);
       else
         AddTemplateOverloadCandidate(FunTmpl, F.getPair(),
                                      ExplicitTemplateArgs, Args,
@@ -6240,6 +6374,7 @@ void Sema::AddFunctionCandidates(const U
 void Sema::AddMethodCandidate(DeclAccessPair FoundDecl,
                               QualType ObjectType,
                               Expr::Classification ObjectClassification,
+                              Expr *ThisArg,
                               ArrayRef<Expr *> Args,
                               OverloadCandidateSet& CandidateSet,
                               bool SuppressUserConversions) {
@@ -6255,12 +6390,12 @@ void Sema::AddMethodCandidate(DeclAccess
     AddMethodTemplateCandidate(TD, FoundDecl, ActingContext,
                                /*ExplicitArgs*/ nullptr,
                                ObjectType, ObjectClassification,
-                               Args, CandidateSet,
+                               ThisArg, Args, CandidateSet,
                                SuppressUserConversions);
   } else {
     AddMethodCandidate(cast<CXXMethodDecl>(Decl), FoundDecl, ActingContext,
                        ObjectType, ObjectClassification,
-                       Args,
+                       ThisArg, Args,
                        CandidateSet, SuppressUserConversions);
   }
 }
@@ -6276,7 +6411,7 @@ void
 Sema::AddMethodCandidate(CXXMethodDecl *Method, DeclAccessPair FoundDecl,
                          CXXRecordDecl *ActingContext, QualType ObjectType,
                          Expr::Classification ObjectClassification,
-                         ArrayRef<Expr *> Args,
+                         Expr *ThisArg, ArrayRef<Expr *> Args,
                          OverloadCandidateSet &CandidateSet,
                          bool SuppressUserConversions,
                          bool PartialOverloading) {
@@ -6393,6 +6528,9 @@ Sema::AddMethodCandidate(CXXMethodDecl *
     Candidate.DeductionFailure.Data = FailedAttr;
     return;
   }
+
+  initDiagnoseIfComplaint(*this, CandidateSet, Candidate, Method, Args,
+                          /*MissingImplicitThis=*/!ThisArg, ThisArg);
 }
 
 /// \brief Add a C++ member function template as a candidate to the candidate
@@ -6405,6 +6543,7 @@ Sema::AddMethodTemplateCandidate(Functio
                                  TemplateArgumentListInfo *ExplicitTemplateArgs,
                                  QualType ObjectType,
                                  Expr::Classification ObjectClassification,
+                                 Expr *ThisArg,
                                  ArrayRef<Expr *> Args,
                                  OverloadCandidateSet& CandidateSet,
                                  bool SuppressUserConversions,
@@ -6445,8 +6584,9 @@ Sema::AddMethodTemplateCandidate(Functio
   assert(isa<CXXMethodDecl>(Specialization) &&
          "Specialization is not a member function?");
   AddMethodCandidate(cast<CXXMethodDecl>(Specialization), FoundDecl,
-                     ActingContext, ObjectType, ObjectClassification, Args,
-                     CandidateSet, SuppressUserConversions, PartialOverloading);
+                     ActingContext, ObjectType, ObjectClassification,
+                     /*ThisArg=*/ThisArg, Args, CandidateSet,
+                     SuppressUserConversions, PartialOverloading);
 }
 
 /// \brief Add a C++ function template specialization as a candidate
@@ -6702,6 +6842,8 @@ Sema::AddConversionCandidate(CXXConversi
     Candidate.DeductionFailure.Data = FailedAttr;
     return;
   }
+
+  initDiagnoseIfComplaint(*this, CandidateSet, Candidate, Conversion, None, false, From);
 }
 
 /// \brief Adds a conversion function template specialization
@@ -6854,6 +6996,8 @@ void Sema::AddSurrogateCandidate(CXXConv
     Candidate.DeductionFailure.Data = FailedAttr;
     return;
   }
+
+  initDiagnoseIfComplaint(*this, CandidateSet, Candidate, Conversion, None);
 }
 
 /// \brief Add overload candidates for overloaded operators that are
@@ -6902,10 +7046,8 @@ void Sema::AddMemberOperatorCandidates(O
          Oper != OperEnd;
          ++Oper)
       AddMethodCandidate(Oper.getPair(), Args[0]->getType(),
-                         Args[0]->Classify(Context), 
-                         Args.slice(1),
-                         CandidateSet,
-                         /* SuppressUserConversions = */ false);
+                         Args[0]->Classify(Context), Args[0], Args.slice(1),
+                         CandidateSet, /*SuppressUserConversions=*/false);
   }
 }
 
@@ -8936,6 +9078,17 @@ void Sema::diagnoseEquivalentInternalLin
   }
 }
 
+static bool isCandidateUnavailableDueToDiagnoseIf(const OverloadCandidate &OC) {
+  ArrayRef<DiagnoseIfAttr *> Info = OC.getDiagnoseIfInfo();
+  if (!Info.empty() && Info[0]->isError())
+    return true;
+
+  assert(llvm::all_of(Info,
+                      [](const DiagnoseIfAttr *A) { return !A->isError(); }) &&
+         "DiagnoseIf info shouldn't have mixed warnings and errors.");
+  return false;
+}
+
 /// \brief Computes the best viable function (C++ 13.3.3)
 /// within an overload candidate set.
 ///
@@ -9014,13 +9167,19 @@ OverloadCandidateSet::BestViableFunction
   // Best is the best viable function.
   if (Best->Function &&
       (Best->Function->isDeleted() ||
-       S.isFunctionConsideredUnavailable(Best->Function)))
+       S.isFunctionConsideredUnavailable(Best->Function) ||
+       isCandidateUnavailableDueToDiagnoseIf(*Best)))
     return OR_Deleted;
 
   if (!EquivalentCands.empty())
     S.diagnoseEquivalentInternalLinkageDeclarations(Loc, Best->Function,
                                                     EquivalentCands);
 
+  for (const auto *W : Best->getDiagnoseIfInfo()) {
+    assert(W->isWarning() && "Errors should've been caught earlier!");
+    S.emitDiagnoseIfDiagnostic(Loc, W);
+  }
+
   return OR_Success;
 }
 
@@ -9861,7 +10020,7 @@ static void DiagnoseFailedEnableIfAttr(S
   EnableIfAttr *Attr = static_cast<EnableIfAttr*>(Cand->DeductionFailure.Data);
 
   S.Diag(Callee->getLocation(),
-         diag::note_ovl_candidate_disabled_by_enable_if_attr)
+         diag::note_ovl_candidate_disabled_by_function_cond_attr)
       << Attr->getCond()->getSourceRange() << Attr->getMessage();
 }
 
@@ -9891,21 +10050,28 @@ static void NoteFunctionCandidate(Sema &
   FunctionDecl *Fn = Cand->Function;
 
   // Note deleted candidates, but only if they're viable.
-  if (Cand->Viable && (Fn->isDeleted() ||
-      S.isFunctionConsideredUnavailable(Fn))) {
-    std::string FnDesc;
-    OverloadCandidateKind FnKind =
+  if (Cand->Viable) {
+    if (Fn->isDeleted() || S.isFunctionConsideredUnavailable(Fn)) {
+      std::string FnDesc;
+      OverloadCandidateKind FnKind =
         ClassifyOverloadCandidate(S, Cand->FoundDecl, Fn, FnDesc);
 
-    S.Diag(Fn->getLocation(), diag::note_ovl_candidate_deleted)
-      << FnKind << FnDesc
-      << (Fn->isDeleted() ? (Fn->isDeletedAsWritten() ? 1 : 2) : 0);
-    MaybeEmitInheritedConstructorNote(S, Cand->FoundDecl);
-    return;
-  }
+      S.Diag(Fn->getLocation(), diag::note_ovl_candidate_deleted)
+        << FnKind << FnDesc
+        << (Fn->isDeleted() ? (Fn->isDeletedAsWritten() ? 1 : 2) : 0);
+      MaybeEmitInheritedConstructorNote(S, Cand->FoundDecl);
+      return;
+    }
+    if (isCandidateUnavailableDueToDiagnoseIf(*Cand)) {
+      auto *A = Cand->DiagnoseIfInfo.get<DiagnoseIfAttr *>();
+      assert(A->isError() && "Non-error diagnose_if disables a candidate?");
+      S.Diag(Cand->Function->getLocation(),
+             diag::note_ovl_candidate_disabled_by_function_cond_attr)
+          << A->getCond()->getSourceRange() << A->getMessage();
+      return;
+    }
 
-  // We don't really have anything else to say about viable candidates.
-  if (Cand->Viable) {
+    // We don't really have anything else to say about viable candidates.
     S.NoteOverloadCandidate(Cand->FoundDecl, Fn);
     return;
   }
@@ -12460,6 +12626,16 @@ Sema::BuildCallToMemberFunction(Scope *S
       TemplateArgs = &TemplateArgsBuffer;
     }
 
+    // Poor-programmer's Lazy<Expr *>; isImplicitAccess requires stripping
+    // parens/casts, which would be nice to avoid potentially doing multiple
+    // times.
+    llvm::Optional<Expr *> UnresolvedBase;
+    auto GetUnresolvedBase = [&] {
+      if (!UnresolvedBase.hasValue())
+        UnresolvedBase =
+          UnresExpr->isImplicitAccess() ? nullptr : UnresExpr->getBase();
+      return *UnresolvedBase;
+    };
     for (UnresolvedMemberExpr::decls_iterator I = UnresExpr->decls_begin(),
            E = UnresExpr->decls_end(); I != E; ++I) {
 
@@ -12480,14 +12656,15 @@ Sema::BuildCallToMemberFunction(Scope *S
           continue;
 
         AddMethodCandidate(Method, I.getPair(), ActingDC, ObjectType,
-                           ObjectClassification, Args, CandidateSet,
+                           ObjectClassification,
+                           /*ThisArg=*/GetUnresolvedBase(), Args, CandidateSet,
                            /*SuppressUserConversions=*/false);
       } else {
-        AddMethodTemplateCandidate(cast<FunctionTemplateDecl>(Func),
-                                   I.getPair(), ActingDC, TemplateArgs,
-                                   ObjectType,  ObjectClassification,
-                                   Args, CandidateSet,
-                                   /*SuppressUsedConversions=*/false);
+        AddMethodTemplateCandidate(
+            cast<FunctionTemplateDecl>(Func), I.getPair(), ActingDC,
+            TemplateArgs, ObjectType, ObjectClassification,
+            /*ThisArg=*/GetUnresolvedBase(), Args, CandidateSet,
+            /*SuppressUsedConversions=*/false);
       }
     }
 
@@ -12600,10 +12777,20 @@ Sema::BuildCallToMemberFunction(Scope *S
            diag::err_ovl_no_viable_member_function_in_call)
           << Method << Method->getSourceRange();
       Diag(Method->getLocation(),
-           diag::note_ovl_candidate_disabled_by_enable_if_attr)
+           diag::note_ovl_candidate_disabled_by_function_cond_attr)
           << Attr->getCond()->getSourceRange() << Attr->getMessage();
       return ExprError();
     }
+
+    SmallVector<DiagnoseIfAttr *, 4> Nonfatal;
+    if (const DiagnoseIfAttr *Attr = checkArgDependentDiagnoseIf(
+            Method, Args, Nonfatal, false, MemE->getBase())) {
+      emitDiagnoseIfDiagnostic(MemE->getMemberLoc(), Attr);
+      return ExprError();
+    }
+
+    for (const auto *Attr : Nonfatal)
+      emitDiagnoseIfDiagnostic(MemE->getMemberLoc(), Attr);
   }
 
   if ((isa<CXXConstructorDecl>(CurContext) || 
@@ -12683,7 +12870,7 @@ Sema::BuildCallToObjectOfClassType(Scope
        Oper != OperEnd; ++Oper) {
     AddMethodCandidate(Oper.getPair(), Object.get()->getType(),
                        Object.get()->Classify(Context),
-                       Args, CandidateSet,
+                       Object.get(), Args, CandidateSet,
                        /*SuppressUserConversions=*/ false);
   }
 
@@ -12959,7 +13146,8 @@ Sema::BuildOverloadedArrowExpr(Scope *S,
   for (LookupResult::iterator Oper = R.begin(), OperEnd = R.end();
        Oper != OperEnd; ++Oper) {
     AddMethodCandidate(Oper.getPair(), Base->getType(), Base->Classify(Context),
-                       None, CandidateSet, /*SuppressUserConversions=*/false);
+                       Base, None, CandidateSet,
+                       /*SuppressUserConversions=*/false);
   }
 
   bool HadMultipleCandidates = (CandidateSet.size() > 1);

Modified: cfe/trunk/lib/Sema/SemaTemplateInstantiateDecl.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaTemplateInstantiateDecl.cpp?rev=291418&r1=291417&r2=291418&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaTemplateInstantiateDecl.cpp (original)
+++ cfe/trunk/lib/Sema/SemaTemplateInstantiateDecl.cpp Sun Jan  8 22:12:14 2017
@@ -168,40 +168,59 @@ static void instantiateDependentAlignVal
                         Aligned->getSpellingListIndex());
 }
 
-static void instantiateDependentEnableIfAttr(
+static Expr *instantiateDependentFunctionAttrCondition(
     Sema &S, const MultiLevelTemplateArgumentList &TemplateArgs,
-    const EnableIfAttr *A, const Decl *Tmpl, Decl *New) {
+    const Attr *A, Expr *OldCond, const Decl *Tmpl, FunctionDecl *New) {
   Expr *Cond = nullptr;
   {
-    Sema::ContextRAII SwitchContext(S, cast<FunctionDecl>(New));
+    Sema::ContextRAII SwitchContext(S, New);
     EnterExpressionEvaluationContext Unevaluated(S, Sema::ConstantEvaluated);
-    ExprResult Result = S.SubstExpr(A->getCond(), TemplateArgs);
+    ExprResult Result = S.SubstExpr(OldCond, TemplateArgs);
     if (Result.isInvalid())
-      return;
+      return nullptr;
     Cond = Result.getAs<Expr>();
   }
   if (!Cond->isTypeDependent()) {
     ExprResult Converted = S.PerformContextuallyConvertToBool(Cond);
     if (Converted.isInvalid())
-      return;
+      return nullptr;
     Cond = Converted.get();
   }
 
   SmallVector<PartialDiagnosticAt, 8> Diags;
-  if (A->getCond()->isValueDependent() && !Cond->isValueDependent() &&
-      !Expr::isPotentialConstantExprUnevaluated(Cond, cast<FunctionDecl>(New),
-                                                Diags)) {
-    S.Diag(A->getLocation(), diag::err_enable_if_never_constant_expr);
-    for (int I = 0, N = Diags.size(); I != N; ++I)
-      S.Diag(Diags[I].first, Diags[I].second);
-    return;
+  if (OldCond->isValueDependent() && !Cond->isValueDependent() &&
+      !Expr::isPotentialConstantExprUnevaluated(Cond, New, Diags)) {
+    S.Diag(A->getLocation(), diag::err_attr_cond_never_constant_expr) << A;
+    for (const auto &P : Diags)
+      S.Diag(P.first, P.second);
+    return nullptr;
   }
+  return Cond;
+}
 
-  EnableIfAttr *EIA = new (S.getASTContext())
-                        EnableIfAttr(A->getLocation(), S.getASTContext(), Cond,
-                                     A->getMessage(),
-                                     A->getSpellingListIndex());
-  New->addAttr(EIA);
+static void instantiateDependentEnableIfAttr(
+    Sema &S, const MultiLevelTemplateArgumentList &TemplateArgs,
+    const EnableIfAttr *EIA, const Decl *Tmpl, FunctionDecl *New) {
+  Expr *Cond = instantiateDependentFunctionAttrCondition(
+      S, TemplateArgs, EIA, EIA->getCond(), Tmpl, New);
+
+  if (Cond)
+    New->addAttr(new (S.getASTContext()) EnableIfAttr(
+        EIA->getLocation(), S.getASTContext(), Cond, EIA->getMessage(),
+        EIA->getSpellingListIndex()));
+}
+
+static void instantiateDependentDiagnoseIfAttr(
+    Sema &S, const MultiLevelTemplateArgumentList &TemplateArgs,
+    const DiagnoseIfAttr *DIA, const Decl *Tmpl, FunctionDecl *New) {
+  Expr *Cond = instantiateDependentFunctionAttrCondition(
+      S, TemplateArgs, DIA, DIA->getCond(), Tmpl, New);
+
+  if (Cond)
+    New->addAttr(new (S.getASTContext()) DiagnoseIfAttr(
+        DIA->getLocation(), S.getASTContext(), Cond, DIA->getMessage(),
+        DIA->getDiagnosticType(), DIA->getArgDependent(), New,
+        DIA->getSpellingListIndex()));
 }
 
 // Constructs and adds to New a new instance of CUDALaunchBoundsAttr using
@@ -335,7 +354,13 @@ void Sema::InstantiateAttrs(const MultiL
 
     if (const auto *EnableIf = dyn_cast<EnableIfAttr>(TmplAttr)) {
       instantiateDependentEnableIfAttr(*this, TemplateArgs, EnableIf, Tmpl,
-                                       New);
+                                       cast<FunctionDecl>(New));
+      continue;
+    }
+
+    if (const auto *DiagnoseIf = dyn_cast<DiagnoseIfAttr>(TmplAttr)) {
+      instantiateDependentDiagnoseIfAttr(*this, TemplateArgs, DiagnoseIf, Tmpl,
+                                         cast<FunctionDecl>(New));
       continue;
     }
 

Added: cfe/trunk/test/Sema/diagnose_if.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/diagnose_if.c?rev=291418&view=auto
==============================================================================
--- cfe/trunk/test/Sema/diagnose_if.c (added)
+++ cfe/trunk/test/Sema/diagnose_if.c Sun Jan  8 22:12:14 2017
@@ -0,0 +1,152 @@
+// RUN: %clang_cc1 %s -verify -fno-builtin
+
+#define _diagnose_if(...) __attribute__((diagnose_if(__VA_ARGS__)))
+
+void failure() _diagnose_if(); // expected-error{{exactly 3 arguments}}
+void failure() _diagnose_if(0); // expected-error{{exactly 3 arguments}}
+void failure() _diagnose_if(0, ""); // expected-error{{exactly 3 arguments}}
+void failure() _diagnose_if(0, "", "error", 1); // expected-error{{exactly 3 arguments}}
+void failure() _diagnose_if(0, 0, "error"); // expected-error{{requires a string}}
+void failure() _diagnose_if(0, "", "invalid"); // expected-error{{invalid diagnostic type for 'diagnose_if'; use "error" or "warning" instead}}
+void failure() _diagnose_if(0, "", "ERROR"); // expected-error{{invalid diagnostic type}}
+void failure(int a) _diagnose_if(a, "", ""); // expected-error{{invalid diagnostic type}}
+void failure() _diagnose_if(a, "", ""); // expected-error{{undeclared identifier 'a'}}
+
+int globalVar;
+void never_constant() _diagnose_if(globalVar, "", "error"); // expected-error{{'diagnose_if' attribute expression never produces a constant expression}} expected-note{{subexpression not valid}}
+void never_constant() _diagnose_if(globalVar, "", "warning"); // expected-error{{'diagnose_if' attribute expression never produces a constant expression}} expected-note{{subexpression not valid}}
+
+int alwaysok(int q) _diagnose_if(0, "", "error");
+int neverok(int q) _diagnose_if(1, "oh no", "error"); // expected-note 5{{from 'diagnose_if' attribute on 'neverok'}}
+int alwayswarn(int q) _diagnose_if(1, "oh no", "warning"); // expected-note 5{{from 'diagnose_if' attribute}}
+int neverwarn(int q) _diagnose_if(0, "", "warning");
+
+void runConstant() {
+  int m;
+  alwaysok(0);
+  alwaysok(1);
+  alwaysok(m);
+
+  {
+    int (*pok)(int) = alwaysok;
+    pok = &alwaysok;
+  }
+
+  neverok(0); // expected-error{{oh no}}
+  neverok(1); // expected-error{{oh no}}
+  neverok(m); // expected-error{{oh no}}
+  {
+    int (*pok)(int) = neverok; // expected-error{{oh no}}
+    pok = &neverok; // expected-error{{oh no}}
+  }
+
+  alwayswarn(0); // expected-warning{{oh no}}
+  alwayswarn(1); // expected-warning{{oh no}}
+  alwayswarn(m); // expected-warning{{oh no}}
+  {
+    int (*pok)(int) = alwayswarn; // expected-warning{{oh no}}
+    pok = &alwayswarn; // expected-warning{{oh no}}
+  }
+
+  neverwarn(0);
+  neverwarn(1);
+  neverwarn(m);
+  {
+    int (*pok)(int) = neverwarn;
+    pok = &neverwarn;
+  }
+}
+
+int abs(int q) _diagnose_if(q >= 0, "redundant abs call", "error"); //expected-note{{from 'diagnose_if'}}
+void runVariable() {
+  int m;
+  abs(-1);
+  abs(1); // expected-error{{redundant abs call}}
+  abs(m);
+
+  int (*pabs)(int) = abs;
+  pabs = &abs;
+}
+
+#define _overloadable __attribute__((overloadable))
+
+int ovl1(const char *n) _overloadable _diagnose_if(n, "oh no", "error"); // expected-note{{oh no}}
+int ovl1(void *m) _overloadable; // expected-note{{candidate function}}
+
+int ovl2(const char *n) _overloadable _diagnose_if(n, "oh no", "error"); // expected-note{{candidate function}}
+int ovl2(char *m) _overloadable; // expected-note{{candidate function}}
+void overloadsYay() {
+  ovl1((void *)0);
+  ovl1(""); // expected-error{{call to unavailable function}}
+
+  ovl2((void *)0); // expected-error{{ambiguous}}
+}
+
+void errorWarnDiagnose1() _diagnose_if(1, "oh no", "error") // expected-note{{from 'diagnose_if'}}
+  _diagnose_if(1, "nop", "warning");
+void errorWarnDiagnose2() _diagnose_if(1, "oh no", "error") // expected-note{{from 'diagnose_if'}}
+  _diagnose_if(1, "nop", "error");
+void errorWarnDiagnose3() _diagnose_if(1, "nop", "warning")
+  _diagnose_if(1, "oh no", "error"); // expected-note{{from 'diagnose_if'}}
+
+void errorWarnDiagnoseArg1(int a) _diagnose_if(a == 1, "oh no", "error") // expected-note{{from 'diagnose_if'}}
+  _diagnose_if(a == 1, "nop", "warning");
+void errorWarnDiagnoseArg2(int a) _diagnose_if(a == 1, "oh no", "error") // expected-note{{from 'diagnose_if'}}
+  _diagnose_if(a == 1, "nop", "error");
+void errorWarnDiagnoseArg3(int a) _diagnose_if(a == 1, "nop", "warning")
+  _diagnose_if(a == 1, "oh no", "error"); // expected-note{{from 'diagnose_if'}}
+
+void runErrorWarnDiagnose() {
+  errorWarnDiagnose1(); // expected-error{{oh no}}
+  errorWarnDiagnose2(); // expected-error{{oh no}}
+  errorWarnDiagnose3(); // expected-error{{oh no}}
+
+  errorWarnDiagnoseArg1(1); // expected-error{{oh no}}
+  errorWarnDiagnoseArg2(1); // expected-error{{oh no}}
+  errorWarnDiagnoseArg3(1); // expected-error{{oh no}}
+}
+
+void warnWarnDiagnose() _diagnose_if(1, "oh no!", "warning") _diagnose_if(1, "foo", "warning"); // expected-note 2{{from 'diagnose_if'}}
+void runWarnWarnDiagnose() {
+  warnWarnDiagnose(); // expected-warning{{oh no!}} expected-warning{{foo}}
+}
+
+void declsStackErr1(int a) _diagnose_if(a & 1, "decl1", "error"); // expected-note 2{{from 'diagnose_if'}}
+void declsStackErr1(int a) _diagnose_if(a & 2, "decl2", "error"); // expected-note{{from 'diagnose_if'}}
+void declsStackErr2();
+void declsStackErr2() _diagnose_if(1, "complaint", "error"); // expected-note{{from 'diagnose_if'}}
+void declsStackErr3() _diagnose_if(1, "complaint", "error"); // expected-note{{from 'diagnose_if'}}
+void declsStackErr3();
+void runDeclsStackErr() {
+  declsStackErr1(0);
+  declsStackErr1(1); // expected-error{{decl1}}
+  declsStackErr1(2); // expected-error{{decl2}}
+  declsStackErr1(3); // expected-error{{decl1}}
+  declsStackErr2(); // expected-error{{complaint}}
+  declsStackErr3(); // expected-error{{complaint}}
+}
+
+void declsStackWarn1(int a) _diagnose_if(a & 1, "decl1", "warning"); // expected-note 2{{from 'diagnose_if'}}
+void declsStackWarn1(int a) _diagnose_if(a & 2, "decl2", "warning"); // expected-note 2{{from 'diagnose_if'}}
+void declsStackWarn2();
+void declsStackWarn2() _diagnose_if(1, "complaint", "warning"); // expected-note{{from 'diagnose_if'}}
+void declsStackWarn3() _diagnose_if(1, "complaint", "warning"); // expected-note{{from 'diagnose_if'}}
+void declsStackWarn3();
+void runDeclsStackWarn() {
+  declsStackWarn1(0);
+  declsStackWarn1(1); // expected-warning{{decl1}}
+  declsStackWarn1(2); // expected-warning{{decl2}}
+  declsStackWarn1(3); // expected-warning{{decl1}} expected-warning{{decl2}}
+  declsStackWarn2(); // expected-warning{{complaint}}
+  declsStackWarn3(); // expected-warning{{complaint}}
+}
+
+void noMsg(int n) _diagnose_if(n, "", "warning"); // expected-note{{from 'diagnose_if'}}
+void runNoMsg() {
+  noMsg(1); // expected-warning{{<no message provided>}}
+}
+
+void alwaysWarnWithArg(int a) _diagnose_if(1 || a, "alwaysWarn", "warning"); // expected-note{{from 'diagnose_if'}}
+void runAlwaysWarnWithArg(int a) {
+  alwaysWarnWithArg(a); // expected-warning{{alwaysWarn}}
+}

Added: cfe/trunk/test/SemaCXX/diagnose_if.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/diagnose_if.cpp?rev=291418&view=auto
==============================================================================
--- cfe/trunk/test/SemaCXX/diagnose_if.cpp (added)
+++ cfe/trunk/test/SemaCXX/diagnose_if.cpp Sun Jan  8 22:12:14 2017
@@ -0,0 +1,460 @@
+// RUN: %clang_cc1 %s -verify -fno-builtin -std=c++14
+
+#define _diagnose_if(...) __attribute__((diagnose_if(__VA_ARGS__)))
+
+namespace type_dependent {
+template <typename T>
+void neverok() _diagnose_if(!T(), "oh no", "error") {} // expected-note 4{{from 'diagnose_if'}}
+
+template <typename T>
+void alwaysok() _diagnose_if(T(), "oh no", "error") {}
+
+template <typename T>
+void alwayswarn() _diagnose_if(!T(), "oh no", "warning") {} // expected-note 4{{from 'diagnose_if'}}
+
+template <typename T>
+void neverwarn() _diagnose_if(T(), "oh no", "warning") {}
+
+void runAll() {
+  alwaysok<int>();
+  alwaysok<int>();
+
+  {
+    void (*pok)() = alwaysok<int>;
+    pok = &alwaysok<int>;
+  }
+
+  neverok<int>(); // expected-error{{oh no}}
+  neverok<short>(); // expected-error{{oh no}}
+
+  {
+    void (*pok)() = neverok<int>; // expected-error{{oh no}}
+  }
+  {
+    void (*pok)();
+    pok = &neverok<int>; // expected-error{{oh no}}
+  }
+
+  alwayswarn<int>(); // expected-warning{{oh no}}
+  alwayswarn<short>(); // expected-warning{{oh no}}
+  {
+    void (*pok)() = alwayswarn<int>; // expected-warning{{oh no}}
+    pok = &alwayswarn<int>; // expected-warning{{oh no}}
+  }
+
+  neverwarn<int>();
+  neverwarn<short>();
+  {
+    void (*pok)() = neverwarn<int>;
+    pok = &neverwarn<int>;
+  }
+}
+
+template <typename T>
+void errorIf(T a) _diagnose_if(T() != a, "oh no", "error") {} // expected-note {{candidate disabled: oh no}}
+
+template <typename T>
+void warnIf(T a) _diagnose_if(T() != a, "oh no", "warning") {} // expected-note {{from 'diagnose_if'}}
+
+void runIf() {
+  errorIf(0);
+  errorIf(1); // expected-error{{call to unavailable function}}
+
+  warnIf(0);
+  warnIf(1); // expected-warning{{oh no}}
+}
+}
+
+namespace value_dependent {
+template <int N>
+void neverok() _diagnose_if(N == 0 || N != 0, "oh no", "error") {} // expected-note 4{{from 'diagnose_if'}}
+
+template <int N>
+void alwaysok() _diagnose_if(N == 0 && N != 0, "oh no", "error") {}
+
+template <int N>
+void alwayswarn() _diagnose_if(N == 0 || N != 0, "oh no", "warning") {} // expected-note 4{{from 'diagnose_if'}}
+
+template <int N>
+void neverwarn() _diagnose_if(N == 0 && N != 0, "oh no", "warning") {}
+
+void runAll() {
+  alwaysok<0>();
+  alwaysok<1>();
+
+  {
+    void (*pok)() = alwaysok<0>;
+    pok = &alwaysok<0>;
+  }
+
+  neverok<0>(); // expected-error{{oh no}}
+  neverok<1>(); // expected-error{{oh no}}
+
+  {
+    void (*pok)() = neverok<0>; // expected-error{{oh no}}
+  }
+  {
+    void (*pok)();
+    pok = &neverok<0>; // expected-error{{oh no}}
+  }
+
+  alwayswarn<0>(); // expected-warning{{oh no}}
+  alwayswarn<1>(); // expected-warning{{oh no}}
+  {
+    void (*pok)() = alwayswarn<0>; // expected-warning{{oh no}}
+    pok = &alwayswarn<0>; // expected-warning{{oh no}}
+  }
+
+  neverwarn<0>();
+  neverwarn<1>();
+  {
+    void (*pok)() = neverwarn<0>;
+    pok = &neverwarn<0>;
+  }
+}
+
+template <int N>
+void errorIf(int a) _diagnose_if(N != a, "oh no", "error") {} // expected-note {{candidate disabled: oh no}}
+
+template <int N>
+void warnIf(int a) _diagnose_if(N != a, "oh no", "warning") {} // expected-note {{from 'diagnose_if'}}
+
+void runIf() {
+  errorIf<0>(0);
+  errorIf<0>(1); // expected-error{{call to unavailable function}}
+
+  warnIf<0>(0);
+  warnIf<0>(1); // expected-warning{{oh no}}
+}
+}
+
+namespace no_overload_interaction {
+void foo(int) _diagnose_if(1, "oh no", "error"); // expected-note{{from 'diagnose_if'}}
+void foo(short);
+
+void bar(int);
+void bar(short) _diagnose_if(1, "oh no", "error");
+
+void fooArg(int a) _diagnose_if(a, "oh no", "error"); // expected-note{{candidate disabled: oh no}}
+void fooArg(short); // expected-note{{candidate function}}
+
+void barArg(int);
+void barArg(short a) _diagnose_if(a, "oh no", "error");
+
+void runAll() {
+  foo(1); // expected-error{{oh no}}
+  bar(1);
+
+  fooArg(1); // expected-error{{call to unavailable function}}
+  barArg(1);
+
+  auto p = foo; // expected-error{{incompatible initializer of type '<overloaded function type>'}}
+}
+}
+
+namespace with_default_args {
+void foo(int a = 0) _diagnose_if(a, "oh no", "warning"); // expected-note 1{{from 'diagnose_if'}}
+void bar(int a = 1) _diagnose_if(a, "oh no", "warning"); // expected-note 2{{from 'diagnose_if'}}
+
+void runAll() {
+  foo();
+  foo(0);
+  foo(1); // expected-warning{{oh no}}
+
+  bar(); // expected-warning{{oh no}}
+  bar(0);
+  bar(1); // expected-warning{{oh no}}
+}
+}
+
+namespace naked_mem_expr {
+struct Foo {
+  void foo(int a) _diagnose_if(a, "should warn", "warning"); // expected-note{{from 'diagnose_if'}}
+  void bar(int a) _diagnose_if(a, "oh no", "error"); // expected-note{{from 'diagnose_if'}}
+};
+
+void runFoo() {
+  Foo().foo(0);
+  Foo().foo(1); // expected-warning{{should warn}}
+
+  Foo().bar(0);
+  Foo().bar(1); // expected-error{{oh no}}
+}
+}
+
+namespace class_template {
+template <typename T>
+struct Errors {
+  void foo(int i) _diagnose_if(i, "bad i", "error"); // expected-note{{from 'diagnose_if'}}
+  void bar(int i) _diagnose_if(i != T(), "bad i", "error"); // expected-note{{from 'diagnose_if'}}
+
+  void fooOvl(int i) _diagnose_if(i, "int bad i", "error"); // expected-note 2{{int bad i}}
+  void fooOvl(short i) _diagnose_if(i, "short bad i", "error"); // expected-note 2{{short bad i}}
+
+  void barOvl(int i) _diagnose_if(i != T(), "int bad i", "error"); // expected-note 2{{int bad i}}
+  void barOvl(short i) _diagnose_if(i != T(), "short bad i", "error"); // expected-note 2{{short bad i}}
+};
+
+void runErrors() {
+  Errors<int>().foo(0);
+  Errors<int>().foo(1); // expected-error{{bad i}}
+
+  Errors<int>().bar(0);
+  Errors<int>().bar(1); // expected-error{{bad i}}
+
+  Errors<int>().fooOvl(0);
+  Errors<int>().fooOvl(1); // expected-error{{call to unavailable}}
+  Errors<int>().fooOvl(short(0));
+  Errors<int>().fooOvl(short(1)); // expected-error{{call to unavailable}}
+
+  Errors<int>().barOvl(0);
+  Errors<int>().barOvl(1); // expected-error{{call to unavailable}}
+  Errors<int>().barOvl(short(0));
+  Errors<int>().barOvl(short(1)); // expected-error{{call to unavailable}}
+}
+
+template <typename T>
+struct Warnings {
+  void foo(int i) _diagnose_if(i, "bad i", "warning"); // expected-note{{from 'diagnose_if'}}
+  void bar(int i) _diagnose_if(i != T(), "bad i", "warning"); // expected-note{{from 'diagnose_if'}}
+
+  void fooOvl(int i) _diagnose_if(i, "int bad i", "warning"); // expected-note{{from 'diagnose_if'}}
+  void fooOvl(short i) _diagnose_if(i, "short bad i", "warning"); // expected-note{{from 'diagnose_if'}}
+
+  void barOvl(int i) _diagnose_if(i != T(), "int bad i", "warning"); // expected-note{{from 'diagnose_if'}}
+  void barOvl(short i) _diagnose_if(i != T(), "short bad i", "warning"); // expected-note{{from 'diagnose_if'}}
+};
+
+void runWarnings() {
+  Warnings<int>().foo(0);
+  Warnings<int>().foo(1); // expected-warning{{bad i}}
+
+  Warnings<int>().bar(0);
+  Warnings<int>().bar(1); // expected-warning{{bad i}}
+
+  Warnings<int>().fooOvl(0);
+  Warnings<int>().fooOvl(1); // expected-warning{{int bad i}}
+  Warnings<int>().fooOvl(short(0));
+  Warnings<int>().fooOvl(short(1)); // expected-warning{{short bad i}}
+
+  Warnings<int>().barOvl(0);
+  Warnings<int>().barOvl(1); // expected-warning{{int bad i}}
+  Warnings<int>().barOvl(short(0));
+  Warnings<int>().barOvl(short(1)); // expected-warning{{short bad i}}
+}
+}
+
+namespace template_specialization {
+template <typename T>
+struct Foo {
+  void foo() _diagnose_if(1, "override me", "error"); // expected-note{{from 'diagnose_if'}}
+  void bar(int i) _diagnose_if(i, "bad i", "error"); // expected-note{{from 'diagnose_if'}}
+  void baz(int i);
+};
+
+template <>
+struct Foo<int> {
+  void foo();
+  void bar(int i);
+  void baz(int i) _diagnose_if(i, "bad i", "error"); // expected-note{{from 'diagnose_if'}}
+};
+
+void runAll() {
+  Foo<double>().foo(); // expected-error{{override me}}
+  Foo<int>().foo();
+
+  Foo<double>().bar(1); // expected-error{{bad i}}
+  Foo<int>().bar(1);
+
+  Foo<double>().baz(1);
+  Foo<int>().baz(1); // expected-error{{bad i}}
+}
+}
+
+namespace late_constexpr {
+constexpr int foo();
+constexpr int foo(int a);
+
+void bar() _diagnose_if(foo(), "bad foo", "error"); // expected-note{{from 'diagnose_if'}} expected-note{{not viable: requires 0 arguments}}
+void bar(int a) _diagnose_if(foo(a), "bad foo", "error"); // expected-note{{bad foo}}
+
+void early() {
+  bar();
+  bar(0);
+  bar(1);
+}
+
+constexpr int foo() { return 1; }
+constexpr int foo(int a) { return a; }
+
+void late() {
+  bar(); // expected-error{{bad foo}}
+  bar(0);
+  bar(1); // expected-error{{call to unavailable function}}
+}
+}
+
+namespace late_parsed {
+struct Foo {
+  int i;
+  constexpr Foo(int i): i(i) {}
+  constexpr bool isFooable() const { return i; }
+
+  void go() const _diagnose_if(isFooable(), "oh no", "error") {} // expected-note{{from 'diagnose_if'}}
+  operator int() const _diagnose_if(isFooable(), "oh no", "error") { return 1; } // expected-note{{oh no}}
+
+  void go2() const _diagnose_if(isFooable(), "oh no", "error") // expected-note{{oh no}}
+      __attribute__((enable_if(true, ""))) {}
+  void go2() const _diagnose_if(isFooable(), "oh no", "error") {} // expected-note{{oh no}}
+
+  constexpr int go3() const _diagnose_if(isFooable(), "oh no", "error")
+      __attribute__((enable_if(true, ""))) {
+    return 1;
+  }
+
+  constexpr int go4() const _diagnose_if(isFooable(), "oh no", "error") {
+    return 1;
+  }
+  constexpr int go4() const _diagnose_if(isFooable(), "oh no", "error")
+      __attribute__((enable_if(true, ""))) {
+    return 1;
+  }
+
+  // We hope to support emitting these errors in the future. For now, though...
+  constexpr int runGo() const {
+    return go3() + go4();
+  }
+};
+
+void go(const Foo &f) _diagnose_if(f.isFooable(), "oh no", "error") {} // expected-note{{oh no}}
+
+void run() {
+  Foo(0).go();
+  Foo(1).go(); // expected-error{{oh no}}
+
+  (void)int(Foo(0));
+  (void)int(Foo(1)); // expected-error{{uses deleted function}}
+
+  Foo(0).go2();
+  Foo(1).go2(); // expected-error{{call to unavailable member function}}
+
+  go(Foo(0));
+  go(Foo(1)); // expected-error{{call to unavailable function}}
+}
+}
+
+namespace member_templates {
+struct Foo {
+  int i;
+  constexpr Foo(int i): i(i) {}
+  constexpr bool bad() const { return i; }
+
+  template <typename T> T getVal() _diagnose_if(bad(), "oh no", "error") { // expected-note{{oh no}}
+    return T();
+  }
+
+  template <typename T>
+  constexpr T getVal2() const _diagnose_if(bad(), "oh no", "error") { // expected-note{{oh no}}
+    return T();
+  }
+
+  template <typename T>
+  constexpr operator T() const _diagnose_if(bad(), "oh no", "error") { // expected-note{{oh no}}
+    return T();
+  }
+
+  // We hope to support emitting these errors in the future.
+  int run() { return getVal<int>() + getVal2<int>() + int(*this); }
+};
+
+void run() {
+  Foo(0).getVal<int>();
+  Foo(1).getVal<int>(); // expected-error{{call to unavailable member function}}
+
+  Foo(0).getVal2<int>();
+  Foo(1).getVal2<int>(); // expected-error{{call to unavailable member function}}
+
+  (void)int(Foo(0));
+  (void)int(Foo(1)); // expected-error{{uses deleted function}}
+}
+}
+
+namespace special_member_operators {
+struct Bar { int j; };
+struct Foo {
+  int i;
+  constexpr Foo(int i): i(i) {}
+  constexpr bool bad() const { return i; }
+  const Bar *operator->() const _diagnose_if(bad(), "oh no", "error") { // expected-note{{oh no}}
+    return nullptr;
+  }
+  void operator()() const _diagnose_if(bad(), "oh no", "error") {} // expected-note{{oh no}}
+};
+
+struct ParenOverload {
+  int i;
+  constexpr ParenOverload(int i): i(i) {}
+  constexpr bool bad() const { return i; }
+  void operator()(double) const _diagnose_if(bad(), "oh no", "error") {} // expected-note 2{{oh no}}
+  void operator()(int) const _diagnose_if(bad(), "oh no", "error") {} // expected-note 2{{oh no}}
+};
+
+struct ParenTemplate {
+  int i;
+  constexpr ParenTemplate(int i): i(i) {}
+  constexpr bool bad() const { return i; }
+  template <typename T>
+  void operator()(T) const _diagnose_if(bad(), "oh no", "error") {} // expected-note 2{{oh no}}
+};
+
+void run() {
+  (void)Foo(0)->j;
+  (void)Foo(1)->j; // expected-error{{selected unavailable operator '->'}}
+
+  Foo(0)();
+  Foo(1)(); // expected-error{{unavailable function call operator}}
+
+  ParenOverload(0)(1);
+  ParenOverload(0)(1.);
+
+  ParenOverload(1)(1); // expected-error{{unavailable function call operator}}
+  ParenOverload(1)(1.); // expected-error{{unavailable function call operator}}
+
+  ParenTemplate(0)(1);
+  ParenTemplate(0)(1.);
+
+  ParenTemplate(1)(1); // expected-error{{unavailable function call operator}}
+  ParenTemplate(1)(1.); // expected-error{{unavailable function call operator}}
+}
+
+void runLambda() {
+  auto L1 = [](int i) _diagnose_if(i, "oh no", "error") {}; // expected-note{{oh no}} expected-note{{conversion candidate}}
+  L1(0);
+  L1(1); // expected-error{{call to unavailable function call}}
+}
+}
+
+namespace ctors {
+struct Foo {
+  int I;
+  constexpr Foo(int I): I(I) {}
+
+  constexpr const Foo &operator=(const Foo &) const // expected-note 2{{disabled: oh no}}
+      _diagnose_if(I, "oh no", "error") {
+    return *this;
+  }
+
+  constexpr const Foo &operator=(const Foo &&) const // expected-note{{disabled: oh no}} expected-note{{no known conversion}}
+      _diagnose_if(I, "oh no", "error") {
+    return *this;
+  }
+};
+
+void run() {
+  constexpr Foo F{0};
+  constexpr Foo F2{1};
+
+  F2 = F; // expected-error{{selected unavailable operator}}
+  F2 = Foo{2}; // expected-error{{selected unavailable operator}}
+}
+}




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