Author: brunoricci Date: Tue Jan 8 05:52:54 2019 New Revision: 350622 URL: http://llvm.org/viewvc/llvm-project?rev=350622&view=rev Log: [Sema] Diagnose array access preceding the array bounds even when the base type is incomplete.
When the type of the base expression after IgnoreParenCasts is incomplete, it is still possible to diagnose an array access which precedes the array bounds. This is a follow-up on D55862 which added an early return when the type of the base expression after IgnoreParenCasts was incomplete. Differential Revision: https://reviews.llvm.org/D56050 Reviewed By: efriedma Modified: cfe/trunk/lib/Sema/SemaChecking.cpp cfe/trunk/test/SemaCXX/array-bounds.cpp Modified: cfe/trunk/lib/Sema/SemaChecking.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaChecking.cpp?rev=350622&r1=350621&r2=350622&view=diff ============================================================================== --- cfe/trunk/lib/Sema/SemaChecking.cpp (original) +++ cfe/trunk/lib/Sema/SemaChecking.cpp Tue Jan 8 05:52:54 2019 @@ -12383,12 +12383,6 @@ void Sema::CheckArrayAccess(const Expr * return; const Type *BaseType = ArrayTy->getElementType().getTypePtr(); - // It is possible that the type of the base expression after IgnoreParenCasts - // is incomplete, even though the type of the base expression before - // IgnoreParenCasts is complete (see PR39746 for an example). In this case we - // have no information about whether the array access is out-of-bounds. - if (BaseType->isIncompleteType()) - return; Expr::EvalResult Result; if (!IndexExpr->EvaluateAsInt(Result, Context, Expr::SE_AllowSideEffects)) @@ -12405,6 +12399,15 @@ void Sema::CheckArrayAccess(const Expr * ND = ME->getMemberDecl(); if (index.isUnsigned() || !index.isNegative()) { + // It is possible that the type of the base expression after + // IgnoreParenCasts is incomplete, even though the type of the base + // expression before IgnoreParenCasts is complete (see PR39746 for an + // example). In this case we have no information about whether the array + // access exceeds the array bounds. However we can still diagnose an array + // access which precedes the array bounds. + if (BaseType->isIncompleteType()) + return; + llvm::APInt size = ArrayTy->getSize(); if (!size.isStrictlyPositive()) return; Modified: cfe/trunk/test/SemaCXX/array-bounds.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/array-bounds.cpp?rev=350622&r1=350621&r2=350622&view=diff ============================================================================== --- cfe/trunk/test/SemaCXX/array-bounds.cpp (original) +++ cfe/trunk/test/SemaCXX/array-bounds.cpp Tue Jan 8 05:52:54 2019 @@ -287,9 +287,12 @@ int test_struct_multiarray() { namespace PR39746 { struct S; - extern S xxx[2]; + extern S xxx[2]; // expected-note {{array 'xxx' declared here}} class C {}; C &f() { return reinterpret_cast<C *>(xxx)[1]; } // no-warning + // We have no info on whether this is out-of-bounds. C &g() { return reinterpret_cast<C *>(xxx)[2]; } // no-warning + // We can still diagnose this. + C &h() { return reinterpret_cast<C *>(xxx)[-1]; } // expected-warning {{array index -1 is before the beginning of the array}} } _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits