r234375 - Generate a diagnostic when a catch handler cannot execute due to class hierarchy inversion with regards to other catch handlers for the same block.
Aaron Ballman
aaron at aaronballman.com
Tue Apr 7 17:05:29 PDT 2015
Author: aaronballman
Date: Tue Apr 7 19:05:29 2015
New Revision: 234375
URL: http://llvm.org/viewvc/llvm-project?rev=234375&view=rev
Log:
Generate a diagnostic when a catch handler cannot execute due to class hierarchy inversion with regards to other catch handlers for the same block.
Modified:
cfe/trunk/include/clang/Basic/DiagnosticGroups.td
cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
cfe/trunk/lib/Sema/SemaStmt.cpp
cfe/trunk/test/CXX/drs/dr3xx.cpp
cfe/trunk/test/Misc/warning-flags.c
cfe/trunk/test/SemaCXX/exceptions.cpp
cfe/trunk/test/SemaCXX/unreachable-catch-clauses.cpp
Modified: cfe/trunk/include/clang/Basic/DiagnosticGroups.td
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticGroups.td?rev=234375&r1=234374&r2=234375&view=diff
==============================================================================
--- cfe/trunk/include/clang/Basic/DiagnosticGroups.td (original)
+++ cfe/trunk/include/clang/Basic/DiagnosticGroups.td Tue Apr 7 19:05:29 2015
@@ -107,6 +107,8 @@ def Documentation : DiagGroup<"documenta
DocumentationDeprecatedSync]>;
def EmptyBody : DiagGroup<"empty-body">;
+def Exceptions : DiagGroup<"exceptions">;
+
def GNUEmptyInitializer : DiagGroup<"gnu-empty-initializer">;
def GNUEmptyStruct : DiagGroup<"gnu-empty-struct">;
def ExtraTokens : DiagGroup<"extra-tokens">;
Modified: cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td?rev=234375&r1=234374&r2=234375&view=diff
==============================================================================
--- cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td (original)
+++ cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td Tue Apr 7 19:05:29 2015
@@ -5475,7 +5475,8 @@ def err_bad_memptr_lhs : Error<
"left hand operand to %0 must be a %select{|pointer to }1class "
"compatible with the right hand operand, but is %2">;
def warn_exception_caught_by_earlier_handler : Warning<
- "exception of type %0 will be caught by earlier handler">;
+ "exception of type %0 will be caught by earlier handler">,
+ InGroup<Exceptions>;
def note_previous_exception_handler : Note<"for type %0">;
def err_exceptions_disabled : Error<
"cannot use '%0' with exceptions disabled">;
Modified: cfe/trunk/lib/Sema/SemaStmt.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaStmt.cpp?rev=234375&r1=234374&r2=234375&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaStmt.cpp (original)
+++ cfe/trunk/lib/Sema/SemaStmt.cpp Tue Apr 7 19:05:29 2015
@@ -15,6 +15,7 @@
#include "clang/AST/ASTContext.h"
#include "clang/AST/ASTDiagnostic.h"
#include "clang/AST/CharUnits.h"
+#include "clang/AST/CXXInheritance.h"
#include "clang/AST/DeclObjC.h"
#include "clang/AST/EvaluatedExprVisitor.h"
#include "clang/AST/ExprCXX.h"
@@ -23,12 +24,14 @@
#include "clang/AST/StmtCXX.h"
#include "clang/AST/StmtObjC.h"
#include "clang/AST/TypeLoc.h"
+#include "clang/AST/TypeOrdering.h"
#include "clang/Lex/Preprocessor.h"
#include "clang/Sema/Initialization.h"
#include "clang/Sema/Lookup.h"
#include "clang/Sema/Scope.h"
#include "clang/Sema/ScopeInfo.h"
#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallString.h"
@@ -3253,36 +3256,111 @@ Sema::ActOnObjCAutoreleasePoolStmt(Sourc
return new (Context) ObjCAutoreleasePoolStmt(AtLoc, Body);
}
-namespace {
+class CatchHandlerType {
+ QualType QT;
+ unsigned IsPointer : 1;
+
+ // This is a special constructor to be used only with DenseMapInfo's
+ // getEmptyKey() and getTombstoneKey() functions.
+ friend struct llvm::DenseMapInfo<CatchHandlerType>;
+ enum Unique { ForDenseMap };
+ CatchHandlerType(QualType QT, Unique) : QT(QT), IsPointer(false) {}
-class TypeWithHandler {
- QualType t;
- CXXCatchStmt *stmt;
public:
- TypeWithHandler(const QualType &type, CXXCatchStmt *statement)
- : t(type), stmt(statement) {}
-
- // An arbitrary order is fine as long as it places identical
- // types next to each other.
- bool operator<(const TypeWithHandler &y) const {
- if (t.getAsOpaquePtr() < y.t.getAsOpaquePtr())
- return true;
- if (t.getAsOpaquePtr() > y.t.getAsOpaquePtr())
+ /// Used when creating a CatchHandlerType from a handler type; will determine
+ /// whether the type is a pointer or reference and will strip off the the top
+ /// level pointer and cv-qualifiers.
+ CatchHandlerType(QualType Q) : QT(Q), IsPointer(false) {
+ if (QT->isPointerType())
+ IsPointer = true;
+
+ if (IsPointer || QT->isReferenceType())
+ QT = QT->getPointeeType();
+ QT = QT.getUnqualifiedType();
+ }
+
+ /// Used when creating a CatchHandlerType from a base class type; pretends the
+ /// type passed in had the pointer qualifier, does not need to get an
+ /// unqualified type.
+ CatchHandlerType(QualType QT, bool IsPointer)
+ : QT(QT), IsPointer(IsPointer) {}
+
+ QualType underlying() const { return QT; }
+ bool isPointer() const { return IsPointer; }
+
+ friend bool operator==(const CatchHandlerType &LHS,
+ const CatchHandlerType &RHS) {
+ // If the pointer qualification does not match, we can return early.
+ if (LHS.IsPointer != RHS.IsPointer)
return false;
- else
- return getTypeSpecStartLoc() < y.getTypeSpecStartLoc();
+ // Otherwise, check the underlying type without cv-qualifiers.
+ return LHS.QT == RHS.QT;
+ }
+};
+
+namespace llvm {
+template <> struct DenseMapInfo<CatchHandlerType> {
+ static CatchHandlerType getEmptyKey() {
+ return CatchHandlerType(DenseMapInfo<QualType>::getEmptyKey(),
+ CatchHandlerType::ForDenseMap);
+ }
+
+ static CatchHandlerType getTombstoneKey() {
+ return CatchHandlerType(DenseMapInfo<QualType>::getTombstoneKey(),
+ CatchHandlerType::ForDenseMap);
}
- bool operator==(const TypeWithHandler& other) const {
- return t == other.t;
+ static unsigned getHashValue(const CatchHandlerType &Base) {
+ return DenseMapInfo<QualType>::getHashValue(Base.underlying());
}
- CXXCatchStmt *getCatchStmt() const { return stmt; }
- SourceLocation getTypeSpecStartLoc() const {
- return stmt->getExceptionDecl()->getTypeSpecStartLoc();
+ static bool isEqual(const CatchHandlerType &LHS,
+ const CatchHandlerType &RHS) {
+ return LHS == RHS;
}
};
+// It's OK to treat CatchHandlerType as a POD type.
+template <> struct isPodLike<CatchHandlerType> {
+ static const bool value = true;
+};
+}
+
+namespace {
+class CatchTypePublicBases {
+ ASTContext &Ctx;
+ const llvm::DenseMap<CatchHandlerType, CXXCatchStmt *> &TypesToCheck;
+ const bool CheckAgainstPointer;
+
+ CXXCatchStmt *FoundHandler;
+ CanQualType FoundHandlerType;
+
+public:
+ CatchTypePublicBases(
+ ASTContext &Ctx,
+ const llvm::DenseMap<CatchHandlerType, CXXCatchStmt *> &T, bool C)
+ : Ctx(Ctx), TypesToCheck(T), CheckAgainstPointer(C),
+ FoundHandler(nullptr) {}
+
+ CXXCatchStmt *getFoundHandler() const { return FoundHandler; }
+ CanQualType getFoundHandlerType() const { return FoundHandlerType; }
+
+ static bool FindPublicBasesOfType(const CXXBaseSpecifier *S, CXXBasePath &,
+ void *User) {
+ auto &PBOT = *reinterpret_cast<CatchTypePublicBases *>(User);
+ if (S->getAccessSpecifier() == AccessSpecifier::AS_public) {
+ CatchHandlerType Check(S->getType(), PBOT.CheckAgainstPointer);
+ auto M = PBOT.TypesToCheck;
+ auto I = M.find(Check);
+ if (I != M.end()) {
+ PBOT.FoundHandler = I->second;
+ PBOT.FoundHandlerType = PBOT.Ctx.getCanonicalType(S->getType());
+ return true;
+ }
+ }
+ return false;
+ }
+};
}
/// ActOnCXXTryBlock - Takes a try compound-statement and a number of
@@ -3292,7 +3370,7 @@ StmtResult Sema::ActOnCXXTryBlock(Source
// Don't report an error if 'try' is used in system headers.
if (!getLangOpts().CXXExceptions &&
!getSourceManager().isInSystemHeader(TryLoc))
- Diag(TryLoc, diag::err_exceptions_disabled) << "try";
+ Diag(TryLoc, diag::err_exceptions_disabled) << "try";
if (getCurScope() && getCurScope()->isOpenMPSimdDirectiveScope())
Diag(TryLoc, diag::err_omp_simd_region_cannot_use_stmt) << "try";
@@ -3306,55 +3384,73 @@ StmtResult Sema::ActOnCXXTryBlock(Source
}
const unsigned NumHandlers = Handlers.size();
- assert(NumHandlers > 0 &&
+ assert(!Handlers.empty() &&
"The parser shouldn't call this if there are no handlers.");
- SmallVector<TypeWithHandler, 8> TypesWithHandlers;
-
+ llvm::DenseMap<CatchHandlerType, CXXCatchStmt *> HandledTypes;
for (unsigned i = 0; i < NumHandlers; ++i) {
- CXXCatchStmt *Handler = cast<CXXCatchStmt>(Handlers[i]);
- if (!Handler->getExceptionDecl()) {
- if (i < NumHandlers - 1)
- return StmtError(Diag(Handler->getLocStart(),
- diag::err_early_catch_all));
+ CXXCatchStmt *H = cast<CXXCatchStmt>(Handlers[i]);
+ // Diagnose when the handler is a catch-all handler, but it isn't the last
+ // handler for the try block. [except.handle]p5. Also, skip exception
+ // declarations that are invalid, since we can't usefully report on them.
+ if (!H->getExceptionDecl()) {
+ if (i < NumHandlers - 1)
+ return StmtError(Diag(H->getLocStart(), diag::err_early_catch_all));
+ continue;
+ } else if (H->getExceptionDecl()->isInvalidDecl())
continue;
- }
-
- const QualType CaughtType = Handler->getCaughtType();
- const QualType CanonicalCaughtType = Context.getCanonicalType(CaughtType);
- TypesWithHandlers.push_back(TypeWithHandler(CanonicalCaughtType, Handler));
- }
-
- // Detect handlers for the same type as an earlier one.
- if (NumHandlers > 1) {
- llvm::array_pod_sort(TypesWithHandlers.begin(), TypesWithHandlers.end());
-
- TypeWithHandler prev = TypesWithHandlers[0];
- for (unsigned i = 1; i < TypesWithHandlers.size(); ++i) {
- TypeWithHandler curr = TypesWithHandlers[i];
- if (curr == prev) {
- Diag(curr.getTypeSpecStartLoc(),
- diag::warn_exception_caught_by_earlier_handler)
- << curr.getCatchStmt()->getCaughtType().getAsString();
- Diag(prev.getTypeSpecStartLoc(),
- diag::note_previous_exception_handler)
- << prev.getCatchStmt()->getCaughtType().getAsString();
+ // Walk the type hierarchy to diagnose when this type has already been
+ // handled (duplication), or cannot be handled (derivation inversion). We
+ // ignore top-level cv-qualifiers, per [except.handle]p3
+ CatchHandlerType HandlerCHT = Context.getCanonicalType(H->getCaughtType());
+
+ // We can ignore whether the type is a reference or a pointer; we need the
+ // underlying declaration type in order to get at the underlying record
+ // decl, if there is one.
+ QualType Underlying = HandlerCHT.underlying();
+ if (auto *RD = Underlying->getAsCXXRecordDecl()) {
+ if (!RD->hasDefinition())
+ continue;
+ // Check that none of the public, unambiguous base classes are in the
+ // map ([except.handle]p1). Give the base classes the same pointer
+ // qualification as the original type we are basing off of. This allows
+ // comparison against the handler type using the same top-level pointer
+ // as the original type.
+ CXXBasePaths Paths;
+ Paths.setOrigin(RD);
+ CatchTypePublicBases CTPB(Context, HandledTypes, HandlerCHT.isPointer());
+ if (RD->lookupInBases(CatchTypePublicBases::FindPublicBasesOfType, &CTPB,
+ Paths)) {
+ const CXXCatchStmt *Problem = CTPB.getFoundHandler();
+ if (!Paths.isAmbiguous(CTPB.getFoundHandlerType())) {
+ Diag(H->getExceptionDecl()->getTypeSpecStartLoc(),
+ diag::warn_exception_caught_by_earlier_handler)
+ << H->getCaughtType();
+ Diag(Problem->getExceptionDecl()->getTypeSpecStartLoc(),
+ diag::note_previous_exception_handler)
+ << Problem->getCaughtType();
+ }
}
+ }
- prev = curr;
+ // Add the type the list of ones we have handled; diagnose if we've already
+ // handled it.
+ auto R = HandledTypes.insert(std::make_pair(H->getCaughtType(), H));
+ if (!R.second) {
+ const CXXCatchStmt *Problem = R.first->second;
+ Diag(H->getExceptionDecl()->getTypeSpecStartLoc(),
+ diag::warn_exception_caught_by_earlier_handler)
+ << H->getCaughtType();
+ Diag(Problem->getExceptionDecl()->getTypeSpecStartLoc(),
+ diag::note_previous_exception_handler)
+ << Problem->getCaughtType();
}
}
FSI->setHasCXXTry(TryLoc);
- // FIXME: We should detect handlers that cannot catch anything because an
- // earlier handler catches a superclass. Need to find a method that is not
- // quadratic for this.
- // Neither of these are explicitly forbidden, but every compiler detects them
- // and warns.
-
return CXXTryStmt::Create(Context, TryLoc, TryBlock, Handlers);
}
Modified: cfe/trunk/test/CXX/drs/dr3xx.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CXX/drs/dr3xx.cpp?rev=234375&r1=234374&r2=234375&view=diff
==============================================================================
--- cfe/trunk/test/CXX/drs/dr3xx.cpp (original)
+++ cfe/trunk/test/CXX/drs/dr3xx.cpp Tue Apr 7 19:05:29 2015
@@ -170,9 +170,9 @@ namespace dr308 { // dr308: yes
void f() {
try {
throw D();
- } catch (const A&) {
+ } catch (const A&) { // expected-note {{for type 'const dr308::A &'}}
// unreachable
- } catch (const B&) {
+ } catch (const B&) { // expected-warning {{exception of type 'const dr308::B &' will be caught by earlier handler}}
// get here instead
}
}
Modified: cfe/trunk/test/Misc/warning-flags.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Misc/warning-flags.c?rev=234375&r1=234374&r2=234375&view=diff
==============================================================================
--- cfe/trunk/test/Misc/warning-flags.c (original)
+++ cfe/trunk/test/Misc/warning-flags.c Tue Apr 7 19:05:29 2015
@@ -18,7 +18,7 @@ This test serves two purposes:
The list of warnings below should NEVER grow. It should gradually shrink to 0.
-CHECK: Warnings without flags (94):
+CHECK: Warnings without flags (93):
CHECK-NEXT: ext_excess_initializers
CHECK-NEXT: ext_excess_initializers_in_char_array_initializer
CHECK-NEXT: ext_expected_semi_decl_list
@@ -68,7 +68,6 @@ CHECK-NEXT: warn_drv_pch_not_first_inc
CHECK-NEXT: warn_dup_category_def
CHECK-NEXT: warn_duplicate_protocol_def
CHECK-NEXT: warn_enum_value_overflow
-CHECK-NEXT: warn_exception_caught_by_earlier_handler
CHECK-NEXT: warn_expected_qualified_after_typename
CHECK-NEXT: warn_extraneous_char_constant
CHECK-NEXT: warn_fe_cc_log_diagnostics_failure
Modified: cfe/trunk/test/SemaCXX/exceptions.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/exceptions.cpp?rev=234375&r1=234374&r2=234375&view=diff
==============================================================================
--- cfe/trunk/test/SemaCXX/exceptions.cpp (original)
+++ cfe/trunk/test/SemaCXX/exceptions.cpp Tue Apr 7 19:05:29 2015
@@ -146,6 +146,82 @@ namespace Decay {
void rval_ref() throw (int &&); // expected-error {{rvalue reference type 'int &&' is not allowed in exception specification}} expected-warning {{C++11}}
+namespace HandlerInversion {
+struct B {};
+struct D : B {};
+struct D2 : D {};
+
+void f1() {
+ try {
+ } catch (B &b) { // expected-note {{for type 'HandlerInversion::B &'}}
+ } catch (D &d) { // expected-warning {{exception of type 'HandlerInversion::D &' will be caught by earlier handler}}
+ }
+}
+
+void f2() {
+ try {
+ } catch (B *b) { // expected-note {{for type 'HandlerInversion::B *'}}
+ } catch (D *d) { // expected-warning {{exception of type 'HandlerInversion::D *' will be caught by earlier handler}}
+ }
+}
+
+void f3() {
+ try {
+ } catch (D &d) { // Ok
+ } catch (B &b) {
+ }
+}
+
+void f4() {
+ try {
+ } catch (B &b) { // Ok
+ }
+}
+
+void f5() {
+ try {
+ } catch (int) {
+ } catch (float) {
+ }
+}
+
+void f6() {
+ try {
+ } catch (B &b) { // expected-note {{for type 'HandlerInversion::B &'}}
+ } catch (D2 &d) { // expected-warning {{exception of type 'HandlerInversion::D2 &' will be caught by earlier handler}}
+ }
+}
+
+void f7() {
+ try {
+ } catch (B *b) { // Ok
+ } catch (D &d) { // Ok
+ }
+
+ try {
+ } catch (B b) { // Ok
+ } catch (D *d) { // Ok
+ }
+}
+
+void f8() {
+ try {
+ } catch (const B &b) { // expected-note {{for type 'const HandlerInversion::B &'}}
+ } catch (D2 &d) { // expected-warning {{exception of type 'HandlerInversion::D2 &' will be caught by earlier handler}}
+ }
+
+ try {
+ } catch (B &b) { // expected-note {{for type 'HandlerInversion::B &'}}
+ } catch (const D2 &d) { // expected-warning {{exception of type 'const HandlerInversion::D2 &' will be caught by earlier handler}}
+ }
+
+ try {
+ } catch (B b) { // expected-note {{for type 'HandlerInversion::B'}}
+ } catch (D &d) { // expected-warning {{exception of type 'HandlerInversion::D &' will be caught by earlier handler}}
+ }
+}
+}
+
namespace ConstVolatileThrow {
struct S {
S() {} // expected-note{{candidate constructor not viable}}
Modified: cfe/trunk/test/SemaCXX/unreachable-catch-clauses.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/unreachable-catch-clauses.cpp?rev=234375&r1=234374&r2=234375&view=diff
==============================================================================
--- cfe/trunk/test/SemaCXX/unreachable-catch-clauses.cpp (original)
+++ cfe/trunk/test/SemaCXX/unreachable-catch-clauses.cpp Tue Apr 7 19:05:29 2015
@@ -8,7 +8,6 @@ void f();
void test()
try {}
-catch (BaseEx &e) { f(); }
-catch (Ex1 &e) { f(); } // expected-note {{for type class Ex1 &}}
-catch (Ex2 &e) { f(); } // expected-warning {{exception of type Ex2 & will be caught by earlier handler}}
-
+catch (BaseEx &e) { f(); } // expected-note 2{{for type 'BaseEx &'}}
+catch (Ex1 &e) { f(); } // expected-warning {{exception of type 'Ex1 &' will be caught by earlier handler}}
+catch (Ex2 &e) { f(); } // expected-warning {{exception of type 'Ex2 &' (aka 'Ex1 &') will be caught by earlier handler}}
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