Generate a diagnostic when a catch handler cannot execute due to class hierarchy inversion with regards to other catch handlers for the same block.
llvm-svn: 234375
diff --git a/clang/lib/Sema/SemaStmt.cpp b/clang/lib/Sema/SemaStmt.cpp
index 0ac9c89..8bf1403 100644
--- a/clang/lib/Sema/SemaStmt.cpp
+++ b/clang/lib/Sema/SemaStmt.cpp
@@ -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 @@
return new (Context) ObjCAutoreleasePoolStmt(AtLoc, Body);
}
-namespace {
+class CatchHandlerType {
+ QualType QT;
+ unsigned IsPointer : 1;
-class TypeWithHandler {
- QualType t;
- CXXCatchStmt *stmt;
+ // 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) {}
+
public:
- TypeWithHandler(const QualType &type, CXXCatchStmt *statement)
- : t(type), stmt(statement) {}
+ /// 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;
- // 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())
+ 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();
- }
-
- bool operator==(const TypeWithHandler& other) const {
- return t == other.t;
- }
-
- CXXCatchStmt *getCatchStmt() const { return stmt; }
- SourceLocation getTypeSpecStartLoc() const {
- return stmt->getExceptionDecl()->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);
+ }
+
+ static unsigned getHashValue(const CatchHandlerType &Base) {
+ return DenseMapInfo<QualType>::getHashValue(Base.underlying());
+ }
+
+ 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 @@
// 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 @@
}
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;
+
+ // 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();
+ }
+ }
}
- 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();
- }
-
- 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);
}