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PR38095: Allow constant-folding of loads through bitcasted pointers if 

the bitcast only changed cvr-qualifications within the pointer type.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@336746 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Richard Smith 2018-07-11 00:29:05 +00:00
parent 295c88685f
commit e7e3affb96
2 changed files with 17 additions and 3 deletions
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10
lib/AST/ExprConstant.cpp
View File

@ -5787,8 +5787,8 @@ bool PointerExprEvaluator::VisitUnaryAddrOf(const UnaryOperator *E) {
return evaluateLValue(E->getSubExpr(), Result);
}
bool PointerExprEvaluator::VisitCastExpr(const CastExpr* E) {
const Expr* SubExpr = E->getSubExpr();
bool PointerExprEvaluator::VisitCastExpr(const CastExpr *E) {
const Expr *SubExpr = E->getSubExpr();
switch (E->getCastKind()) {
default:
@ -5805,7 +5805,11 @@ bool PointerExprEvaluator::VisitCastExpr(const CastExpr* E) {
// permitted in constant expressions in C++11. Bitcasts from cv void* are
// also static_casts, but we disallow them as a resolution to DR1312.
if (!E->getType()->isVoidPointerType()) {
Result.Designator.setInvalid();
// If we changed anything other than cvr-qualifiers, we can't use this
// value for constant folding. FIXME: Qualification conversions should
// always be CK_NoOp, but we get this wrong in C.
if (!Info.Ctx.hasCvrSimilarType(E->getType(), E->getSubExpr()->getType()))
Result.Designator.setInvalid();
if (SubExpr->getType()->isVoidPointerType())
CCEDiag(E, diag::note_constexpr_invalid_cast)
<< 3 << SubExpr->getType();

10
test/Sema/diagnose_if.c
View File

@ -157,3 +157,13 @@ void runAlwaysWarnWithArg(int a) {
// Bug: we would complain about `a` being undeclared if this was spelled
// __diagnose_if__.
void underbarName(int a) __attribute__((__diagnose_if__(a, "", "warning")));
// PR38095
void constCharStar(const char *str) __attribute__((__diagnose_if__(!str[0], "empty string not allowed", "error"))); // expected-note {{from}}
void charStar(char *str) __attribute__((__diagnose_if__(!str[0], "empty string not allowed", "error"))); // expected-note {{from}}
void runConstCharStar() {
constCharStar("foo");
charStar("bar");
constCharStar(""); // expected-error {{empty string not allowed}}
charStar(""); // expected-error {{empty string not allowed}}
}