r304946 - [c++1z] Support deducing B in noexcept(B).
Richard Smith via cfe-commits
cfe-commits at lists.llvm.org
Wed Jun 7 14:46:23 PDT 2017
Author: rsmith
Date: Wed Jun 7 16:46:22 2017
New Revision: 304946
URL: http://llvm.org/viewvc/llvm-project?rev=304946&view=rev
Log:
[c++1z] Support deducing B in noexcept(B).
This is not required by the standard (yet), but there seems to be reasonable
support for this being a defect according to CWG discussion, and libstdc++ 7.1
relies on it working.
Modified:
cfe/trunk/include/clang/Sema/Sema.h
cfe/trunk/lib/Sema/SemaTemplateDeduction.cpp
cfe/trunk/lib/Sema/SemaTemplateInstantiate.cpp
cfe/trunk/test/CXX/drs/dr13xx.cpp
cfe/trunk/test/CXX/temp/temp.fct.spec/temp.deduct/temp.deduct.call/p4.cpp
cfe/trunk/test/SemaCXX/cxx1z-noexcept-function-type.cpp
cfe/trunk/test/SemaTemplate/temp_arg_type.cpp
Modified: cfe/trunk/include/clang/Sema/Sema.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Sema/Sema.h?rev=304946&r1=304945&r2=304946&view=diff
==============================================================================
--- cfe/trunk/include/clang/Sema/Sema.h (original)
+++ cfe/trunk/include/clang/Sema/Sema.h Wed Jun 7 16:46:22 2017
@@ -7555,6 +7555,10 @@ public:
unsigned ThisTypeQuals);
void SubstExceptionSpec(FunctionDecl *New, const FunctionProtoType *Proto,
const MultiLevelTemplateArgumentList &Args);
+ bool SubstExceptionSpec(SourceLocation Loc,
+ FunctionProtoType::ExceptionSpecInfo &ESI,
+ SmallVectorImpl<QualType> &ExceptionStorage,
+ const MultiLevelTemplateArgumentList &Args);
ParmVarDecl *SubstParmVarDecl(ParmVarDecl *D,
const MultiLevelTemplateArgumentList &TemplateArgs,
int indexAdjustment,
Modified: cfe/trunk/lib/Sema/SemaTemplateDeduction.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaTemplateDeduction.cpp?rev=304946&r1=304945&r2=304946&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaTemplateDeduction.cpp (original)
+++ cfe/trunk/lib/Sema/SemaTemplateDeduction.cpp Wed Jun 7 16:46:22 2017
@@ -56,8 +56,12 @@ namespace clang {
TDF_TopLevelParameterTypeList = 0x10,
/// \brief Within template argument deduction from overload resolution per
/// C++ [over.over] allow matching function types that are compatible in
- /// terms of noreturn and default calling convention adjustments.
- TDF_InOverloadResolution = 0x20
+ /// terms of noreturn and default calling convention adjustments, or
+ /// similarly matching a declared template specialization against a
+ /// possible template, per C++ [temp.deduct.decl]. In either case, permit
+ /// deduction where the parameter is a function type that can be converted
+ /// to the argument type.
+ TDF_AllowCompatibleFunctionType = 0x20,
};
}
@@ -1306,9 +1310,10 @@ DeduceTemplateArgumentsByTypeMatch(Sema
// If the parameter type is not dependent, there is nothing to deduce.
if (!Param->isDependentType()) {
if (!(TDF & TDF_SkipNonDependent)) {
- bool NonDeduced = (TDF & TDF_InOverloadResolution)?
- !S.isSameOrCompatibleFunctionType(CanParam, CanArg) :
- Param != Arg;
+ bool NonDeduced =
+ (TDF & TDF_AllowCompatibleFunctionType)
+ ? !S.isSameOrCompatibleFunctionType(CanParam, CanArg)
+ : Param != Arg;
if (NonDeduced) {
return Sema::TDK_NonDeducedMismatch;
}
@@ -1318,10 +1323,10 @@ DeduceTemplateArgumentsByTypeMatch(Sema
} else if (!Param->isDependentType()) {
CanQualType ParamUnqualType = CanParam.getUnqualifiedType(),
ArgUnqualType = CanArg.getUnqualifiedType();
- bool Success = (TDF & TDF_InOverloadResolution)?
- S.isSameOrCompatibleFunctionType(ParamUnqualType,
- ArgUnqualType) :
- ParamUnqualType == ArgUnqualType;
+ bool Success =
+ (TDF & TDF_AllowCompatibleFunctionType)
+ ? S.isSameOrCompatibleFunctionType(ParamUnqualType, ArgUnqualType)
+ : ParamUnqualType == ArgUnqualType;
if (Success)
return Sema::TDK_Success;
}
@@ -1524,17 +1529,56 @@ DeduceTemplateArgumentsByTypeMatch(Sema
return Sema::TDK_NonDeducedMismatch;
// Check return types.
- if (Sema::TemplateDeductionResult Result =
- DeduceTemplateArgumentsByTypeMatch(
- S, TemplateParams, FunctionProtoParam->getReturnType(),
- FunctionProtoArg->getReturnType(), Info, Deduced, 0))
+ if (auto Result = DeduceTemplateArgumentsByTypeMatch(
+ S, TemplateParams, FunctionProtoParam->getReturnType(),
+ FunctionProtoArg->getReturnType(), Info, Deduced, 0))
return Result;
- return DeduceTemplateArguments(
- S, TemplateParams, FunctionProtoParam->param_type_begin(),
- FunctionProtoParam->getNumParams(),
- FunctionProtoArg->param_type_begin(),
- FunctionProtoArg->getNumParams(), Info, Deduced, SubTDF);
+ // Check parameter types.
+ if (auto Result = DeduceTemplateArguments(
+ S, TemplateParams, FunctionProtoParam->param_type_begin(),
+ FunctionProtoParam->getNumParams(),
+ FunctionProtoArg->param_type_begin(),
+ FunctionProtoArg->getNumParams(), Info, Deduced, SubTDF))
+ return Result;
+
+ if (TDF & TDF_AllowCompatibleFunctionType)
+ return Sema::TDK_Success;
+
+ // FIXME: Per core-2016/10/1019 (no corresponding core issue yet), permit
+ // deducing through the noexcept-specifier if it's part of the canonical
+ // type. libstdc++ relies on this.
+ Expr *NoexceptExpr = FunctionProtoParam->getNoexceptExpr();
+ if (NonTypeTemplateParmDecl *NTTP =
+ NoexceptExpr ? getDeducedParameterFromExpr(Info, NoexceptExpr)
+ : nullptr) {
+ assert(NTTP->getDepth() == Info.getDeducedDepth() &&
+ "saw non-type template parameter with wrong depth");
+
+ llvm::APSInt Noexcept(1);
+ switch (FunctionProtoArg->canThrow(S.Context)) {
+ case CT_Cannot:
+ Noexcept = 1;
+ LLVM_FALLTHROUGH;
+
+ case CT_Can:
+ // We give E in noexcept(E) the "deduced from array bound" treatment.
+ // FIXME: Should we?
+ return DeduceNonTypeTemplateArgument(
+ S, TemplateParams, NTTP, Noexcept, S.Context.BoolTy,
+ /*ArrayBound*/true, Info, Deduced);
+
+ case CT_Dependent:
+ if (Expr *ArgNoexceptExpr = FunctionProtoArg->getNoexceptExpr())
+ return DeduceNonTypeTemplateArgument(
+ S, TemplateParams, NTTP, ArgNoexceptExpr, Info, Deduced);
+ // Can't deduce anything from throw(T...).
+ break;
+ }
+ }
+ // FIXME: Detect non-deduced exception specification mismatches?
+
+ return Sema::TDK_Success;
}
case Type::InjectedClassName: {
@@ -1544,7 +1588,7 @@ DeduceTemplateArgumentsByTypeMatch(Sema
->getInjectedSpecializationType();
assert(isa<TemplateSpecializationType>(Param) &&
"injected class name is not a template specialization type");
- // fall through
+ LLVM_FALLTHROUGH;
}
// template-name<T> (where template-name refers to a class template)
@@ -2820,6 +2864,17 @@ Sema::SubstituteExplicitTemplateArgument
if (FunctionType) {
auto EPI = Proto->getExtProtoInfo();
EPI.ExtParameterInfos = ExtParamInfos.getPointerOrNull(ParamTypes.size());
+
+ // In C++1z onwards, exception specifications are part of the function type,
+ // so substitution into the type must also substitute into the exception
+ // specification.
+ SmallVector<QualType, 4> ExceptionStorage;
+ if (getLangOpts().CPlusPlus1z &&
+ SubstExceptionSpec(
+ Function->getLocation(), EPI.ExceptionSpec, ExceptionStorage,
+ MultiLevelTemplateArgumentList(*ExplicitArgumentList)))
+ return TDK_SubstitutionFailure;
+
*FunctionType = BuildFunctionType(ResultType, ParamTypes,
Function->getLocation(),
Function->getDeclName(),
@@ -3714,13 +3769,6 @@ Sema::TemplateDeductionResult Sema::Dedu
= FunctionTemplate->getTemplateParameters();
QualType FunctionType = Function->getType();
- // When taking the address of a function, we require convertibility of
- // the resulting function type. Otherwise, we allow arbitrary mismatches
- // of calling convention, noreturn, and noexcept.
- if (!IsAddressOfFunction)
- ArgFunctionType = adjustCCAndNoReturn(ArgFunctionType, FunctionType,
- /*AdjustExceptionSpec*/true);
-
// Substitute any explicit template arguments.
LocalInstantiationScope InstScope(*this);
SmallVector<DeducedTemplateArgument, 4> Deduced;
@@ -3737,6 +3785,13 @@ Sema::TemplateDeductionResult Sema::Dedu
NumExplicitlySpecified = Deduced.size();
}
+ // When taking the address of a function, we require convertibility of
+ // the resulting function type. Otherwise, we allow arbitrary mismatches
+ // of calling convention and noreturn.
+ if (!IsAddressOfFunction)
+ ArgFunctionType = adjustCCAndNoReturn(ArgFunctionType, FunctionType,
+ /*AdjustExceptionSpec*/false);
+
// Unevaluated SFINAE context.
EnterExpressionEvaluationContext Unevaluated(
*this, Sema::ExpressionEvaluationContext::Unevaluated);
@@ -3756,9 +3811,8 @@ Sema::TemplateDeductionResult Sema::Dedu
}
if (!ArgFunctionType.isNull()) {
- unsigned TDF = TDF_TopLevelParameterTypeList;
- if (IsAddressOfFunction)
- TDF |= TDF_InOverloadResolution;
+ unsigned TDF =
+ TDF_TopLevelParameterTypeList | TDF_AllowCompatibleFunctionType;
// Deduce template arguments from the function type.
if (TemplateDeductionResult Result
= DeduceTemplateArgumentsByTypeMatch(*this, TemplateParams,
@@ -3789,7 +3843,7 @@ Sema::TemplateDeductionResult Sema::Dedu
!ResolveExceptionSpec(Info.getLocation(), SpecializationFPT))
return TDK_MiscellaneousDeductionFailure;
- // Adjust the exception specification of the argument again to match the
+ // Adjust the exception specification of the argument to match the
// substituted and resolved type we just formed. (Calling convention and
// noreturn can't be dependent, so we don't actually need this for them
// right now.)
@@ -5127,6 +5181,8 @@ MarkUsedTemplateParameters(ASTContext &C
for (unsigned I = 0, N = Proto->getNumParams(); I != N; ++I)
MarkUsedTemplateParameters(Ctx, Proto->getParamType(I), OnlyDeduced,
Depth, Used);
+ if (auto *E = Proto->getNoexceptExpr())
+ MarkUsedTemplateParameters(Ctx, E, OnlyDeduced, Depth, Used);
break;
}
Modified: cfe/trunk/lib/Sema/SemaTemplateInstantiate.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaTemplateInstantiate.cpp?rev=304946&r1=304945&r2=304946&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaTemplateInstantiate.cpp (original)
+++ cfe/trunk/lib/Sema/SemaTemplateInstantiate.cpp Wed Jun 7 16:46:22 2017
@@ -1692,20 +1692,26 @@ TypeSourceInfo *Sema::SubstFunctionDeclT
return TLB.getTypeSourceInfo(Context, Result);
}
+bool Sema::SubstExceptionSpec(SourceLocation Loc,
+ FunctionProtoType::ExceptionSpecInfo &ESI,
+ SmallVectorImpl<QualType> &ExceptionStorage,
+ const MultiLevelTemplateArgumentList &Args) {
+ assert(ESI.Type != EST_Uninstantiated);
+
+ bool Changed = false;
+ TemplateInstantiator Instantiator(*this, Args, Loc, DeclarationName());
+ return Instantiator.TransformExceptionSpec(Loc, ESI, ExceptionStorage,
+ Changed);
+}
+
void Sema::SubstExceptionSpec(FunctionDecl *New, const FunctionProtoType *Proto,
const MultiLevelTemplateArgumentList &Args) {
FunctionProtoType::ExceptionSpecInfo ESI =
Proto->getExtProtoInfo().ExceptionSpec;
- assert(ESI.Type != EST_Uninstantiated);
-
- TemplateInstantiator Instantiator(*this, Args, New->getLocation(),
- New->getDeclName());
SmallVector<QualType, 4> ExceptionStorage;
- bool Changed = false;
- if (Instantiator.TransformExceptionSpec(
- New->getTypeSourceInfo()->getTypeLoc().getLocEnd(), ESI,
- ExceptionStorage, Changed))
+ if (SubstExceptionSpec(New->getTypeSourceInfo()->getTypeLoc().getLocEnd(),
+ ESI, ExceptionStorage, Args))
// On error, recover by dropping the exception specification.
ESI.Type = EST_None;
Modified: cfe/trunk/test/CXX/drs/dr13xx.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CXX/drs/dr13xx.cpp?rev=304946&r1=304945&r2=304946&view=diff
==============================================================================
--- cfe/trunk/test/CXX/drs/dr13xx.cpp (original)
+++ cfe/trunk/test/CXX/drs/dr13xx.cpp Wed Jun 7 16:46:22 2017
@@ -192,7 +192,7 @@ namespace dr1330 { // dr1330: 4 c++11
static_assert(!noexcept(B<Q>().g()), "");
#endif
- template<typename T> int f() throw(typename T::error) { return 0; } // expected-error 1-4{{prior to '::'}} expected-note 0-1{{instantiation of}}
+ template<typename T> int f() throw(typename T::error) { return 0; } // expected-error 1-4{{prior to '::'}} expected-note 0-1{{prior to '::'}} expected-note 0-1{{requested here}}
#if __cplusplus > 201402L
// expected-error at -2 0-1{{C++1z}} expected-note at -2 0-1{{noexcept}}
#endif
@@ -203,7 +203,16 @@ namespace dr1330 { // dr1330: 4 c++11
decltype(f<char>()) f2; // expected-note {{instantiation of}}
bool f3 = noexcept(f<float>()); // expected-note {{instantiation of}}
#endif
- template int f<short>(); // expected-note {{instantiation of}}
+ // In C++1z onwards, substituting explicit template arguments into the
+ // function type substitutes into the exception specification (because it's
+ // part of the type). In earlier languages, we don't notice there's a problem
+ // until we've already started to instantiate.
+ template int f<short>();
+#if __cplusplus >= 201703L
+ // expected-error at -2 {{does not refer to a function template}}
+#else
+ // expected-note at -4 {{instantiation of}}
+#endif
template<typename T> struct C {
C() throw(typename T::type); // expected-error 1-2{{prior to '::'}}
Modified: cfe/trunk/test/CXX/temp/temp.fct.spec/temp.deduct/temp.deduct.call/p4.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CXX/temp/temp.fct.spec/temp.deduct/temp.deduct.call/p4.cpp?rev=304946&r1=304945&r2=304946&view=diff
==============================================================================
--- cfe/trunk/test/CXX/temp/temp.fct.spec/temp.deduct/temp.deduct.call/p4.cpp (original)
+++ cfe/trunk/test/CXX/temp/temp.fct.spec/temp.deduct/temp.deduct.call/p4.cpp Wed Jun 7 16:46:22 2017
@@ -46,10 +46,11 @@ namespace noexcept_conversion {
template <class T> int h(T *, T *); // expected-note {{deduced conflicting types for parameter 'T' ('void () noexcept' vs. 'void ()')}}
int x = h(g1, g2); // expected-error {{no matching function}}
- // FIXME: It seems like a defect that B is not deducible here.
- template<bool B> int i(void () noexcept(B)); // expected-note 2{{couldn't infer template argument 'B'}}
- int i1 = i(g1); // expected-error {{no matching function}}
- int i2 = i(g2); // expected-error {{no matching function}}
+ // We consider it a defect that deduction does not support the following.
+ // FIXME: Check that the defect is resolved as we expect.
+ template<bool B> int i(void () noexcept(B));
+ int i1 = i(g1);
+ int i2 = i(g2);
}
#else
// expected-no-diagnostics
Modified: cfe/trunk/test/SemaCXX/cxx1z-noexcept-function-type.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/cxx1z-noexcept-function-type.cpp?rev=304946&r1=304945&r2=304946&view=diff
==============================================================================
--- cfe/trunk/test/SemaCXX/cxx1z-noexcept-function-type.cpp (original)
+++ cfe/trunk/test/SemaCXX/cxx1z-noexcept-function-type.cpp Wed Jun 7 16:46:22 2017
@@ -16,7 +16,7 @@ template<typename A, typename B> void re
typedef int I;
template<bool B> void redecl4(I) noexcept(B);
-template<bool B> void redecl4(I) noexcept(B); // expected-note {{failed template argument deduction}}
+template<bool B> void redecl4(I) noexcept(B); // expected-note {{could not match 'void (I) noexcept(false)' (aka 'void (int) noexcept(false)') against 'void (int) noexcept'}}
void (*init_with_exact_type_a)(int) noexcept = redecl4<true>;
void (*init_with_mismatched_type_a)(int) = redecl4<true>;
Modified: cfe/trunk/test/SemaTemplate/temp_arg_type.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaTemplate/temp_arg_type.cpp?rev=304946&r1=304945&r2=304946&view=diff
==============================================================================
--- cfe/trunk/test/SemaTemplate/temp_arg_type.cpp (original)
+++ cfe/trunk/test/SemaTemplate/temp_arg_type.cpp Wed Jun 7 16:46:22 2017
@@ -1,6 +1,7 @@
// RUN: %clang_cc1 -fsyntax-only -verify %s
// RUN: %clang_cc1 -fsyntax-only -verify -std=c++98 %s
// RUN: %clang_cc1 -fsyntax-only -verify -std=c++11 %s
+// RUN: %clang_cc1 -fsyntax-only -verify -std=c++1z %s
template<typename T> class A; // expected-note 2 {{template parameter is declared here}} expected-note{{template is declared here}}
@@ -53,3 +54,56 @@ A1<Array<int, 17>::type> ax;
// FIXME: [temp.arg.type]p3. The check doesn't really belong here (it
// belongs somewhere in the template instantiation section).
+
+#if __cplusplus >= 201703
+// As a defect resolution, we support deducing B in noexcept(B).
+namespace deduce_noexcept {
+ template<typename> struct function;
+ template<typename R, typename ...A, bool N>
+ struct function<R(A...) noexcept(N)> {
+ static constexpr bool Noexcept = N;
+ };
+ static_assert(function<int(float, double) noexcept>::Noexcept);
+ static_assert(!function<int(float, double)>::Noexcept);
+
+ void noexcept_function() noexcept;
+ void throwing_function();
+
+ template<typename T, bool B> float &deduce_function(T(*)() noexcept(B)); // expected-note {{candidate}}
+ template<typename T> int &deduce_function(T(*)() noexcept); // expected-note {{candidate}}
+ void test_function_deduction() {
+ // FIXME: This should probably unambiguously select the second overload.
+ int &r = deduce_function(noexcept_function); // expected-error {{ambiguous}}
+ float &s = deduce_function(throwing_function);
+ }
+
+ namespace low_priority_deduction {
+ template<int> struct A {};
+ template<auto B> void f(A<B>, void(*)() noexcept(B)) {
+ using T = decltype(B);
+ using T = int;
+ }
+ void g() { f(A<0>(), g); } // ok, deduce B as an int
+ }
+
+ // FIXME: It's not clear whether this should work. We're told to deduce with
+ // P being the function template type and A being the declared type, which
+ // would accept this, but considering the exception specification in such
+ // cases breaks new/delete matching.
+ template<bool Noexcept> void dep() noexcept(Noexcept) {} // expected-note 3{{couldn't infer template argument 'Noexcept'}}
+ template void dep(); // expected-error {{does not refer to a function template}}
+ template void dep() noexcept(true); // expected-error {{does not refer to a function template}}
+ template void dep() noexcept(false); // expected-error {{does not refer to a function template}}
+
+ // FIXME: It's also not clear whether this should be valid: do we substitute
+ // into the function type (including the exception specification) or not?
+ template<typename T> typename T::type1 f() noexcept(T::a);
+ template<typename T> typename T::type2 f() noexcept(T::b) {}
+ struct X {
+ static constexpr bool b = true;
+ using type1 = void;
+ using type2 = void;
+ };
+ template void f<X>();
+}
+#endif
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