Author: brunoricci Date: Thu Dec 20 12:05:11 2018 New Revision: 349811 URL: http://llvm.org/viewvc/llvm-project?rev=349811&view=rev Log: [Sema] Don't try to account for the size of an incomplete type in CheckArrayAccess
When checking that the array access is not out-of-bounds in CheckArrayAccess 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. In this case we have no information about whether the array access is out-of-bounds and we should just bail-out instead. This fixes PR39746 which was caused by trying to obtain the size of an incomplete type. Differential Revision: https://reviews.llvm.org/D55862 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=349811&r1=349810&r2=349811&view=diff ============================================================================== --- cfe/trunk/lib/Sema/SemaChecking.cpp (original) +++ cfe/trunk/lib/Sema/SemaChecking.cpp Thu Dec 20 12:05:11 2018 @@ -12379,10 +12379,19 @@ void Sema::CheckArrayAccess(const Expr * BaseExpr->getType()->getPointeeOrArrayElementType(); BaseExpr = BaseExpr->IgnoreParenCasts(); const ConstantArrayType *ArrayTy = - Context.getAsConstantArrayType(BaseExpr->getType()); + Context.getAsConstantArrayType(BaseExpr->getType()); + if (!ArrayTy) 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)) return; @@ -12402,7 +12411,6 @@ void Sema::CheckArrayAccess(const Expr * if (!size.isStrictlyPositive()) return; - const Type *BaseType = BaseExpr->getType()->getPointeeOrArrayElementType(); if (BaseType != EffectiveType) { // Make sure we're comparing apples to apples when comparing index to size uint64_t ptrarith_typesize = Context.getTypeSize(EffectiveType); Modified: cfe/trunk/test/SemaCXX/array-bounds.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/array-bounds.cpp?rev=349811&r1=349810&r2=349811&view=diff ============================================================================== --- cfe/trunk/test/SemaCXX/array-bounds.cpp (original) +++ cfe/trunk/test/SemaCXX/array-bounds.cpp Thu Dec 20 12:05:11 2018 @@ -284,3 +284,12 @@ struct multi_s multi2[4]; // expected-no int test_struct_multiarray() { return multi2[4].arr[0]; // expected-warning {{array index 4 is past the end of the array (which contains 4 elements)}} } + +namespace PR39746 { + struct S; + extern S xxx[2]; + class C {}; + + C &f() { return reinterpret_cast<C *>(xxx)[1]; } // no-warning + C &g() { return reinterpret_cast<C *>(xxx)[2]; } // no-warning +} _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
