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Finally getting around to re-working this to more accurately white-list 

1-element character arrays which are serving as flexible arrays. This is
the initial step, which is to restrict the 1-element array whitelist to
arrays that are member declarations. I'll refine it from here based on
the proposed patch.

llvm-svn: 136964
This commit is contained in:
Chandler Carruth 2011-08-05 08:07:29 +00:00
parent ff371acaa4
commit 126b155429
1 changed files with 22 additions and 8 deletions
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30
clang/lib/Sema/SemaChecking.cpp
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@ -3489,6 +3489,15 @@ static void CheckArrayAccess_Check(Sema &S,
if (!IndexExpr->isIntegerConstantExpr(index, S.Context))
return;
const NamedDecl *ND = NULL;
bool IsMemberDecl = false;
if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(BaseExpr))
ND = dyn_cast<NamedDecl>(DRE->getDecl());
if (const MemberExpr *ME = dyn_cast<MemberExpr>(BaseExpr)) {
ND = dyn_cast<NamedDecl>(ME->getMemberDecl());
IsMemberDecl = true;
}
if (index.isUnsigned() || !index.isNegative()) {
llvm::APInt size = ArrayTy->getSize();
if (!size.isStrictlyPositive())
@ -3498,9 +3507,19 @@ static void CheckArrayAccess_Check(Sema &S,
else if (size.getBitWidth() < index.getBitWidth())
size = size.sext(index.getBitWidth());
// Don't warn for valid indexes, or arrays of size 1 (which are often
// tail-allocated arrays that are emulating flexible arrays in C89 code).
if (index.slt(size) || size == 1)
// Don't warn for valid indexes
if (index.slt(size))
return;
// Also don't warn for arrays of size 1 which are members of some
// structure. These are often used to approximate flexible arrays in C89
// code.
// FIXME: We should also check whether there are any members after this
// member within the struct as that precludes the usage as a flexible
// array. We should also potentially check for an explicit '1' as opposed
// to a macro or template argument which might accidentally and erroneously
// expand to '1'.
if (IsMemberDecl && size == 1)
return;
S.DiagRuntimeBehavior(E->getBase()->getLocStart(), BaseExpr,
@ -3515,11 +3534,6 @@ static void CheckArrayAccess_Check(Sema &S,
<< IndexExpr->getSourceRange());
}
const NamedDecl *ND = NULL;
if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(BaseExpr))
ND = dyn_cast<NamedDecl>(DRE->getDecl());
if (const MemberExpr *ME = dyn_cast<MemberExpr>(BaseExpr))
ND = dyn_cast<NamedDecl>(ME->getMemberDecl());
if (ND)
S.DiagRuntimeBehavior(ND->getLocStart(), BaseExpr,
S.PDiag(diag::note_array_index_out_of_bounds)