[clang] [-Wunsafe-buffer-usage] Fix false positives for constant cases (PR #92432)
Artem Dergachev via cfe-commits
cfe-commits at lists.llvm.org
Mon May 20 12:44:38 PDT 2024
================
@@ -420,25 +420,63 @@ AST_MATCHER(ArraySubscriptExpr, isSafeArraySubscript) {
// already duplicated
// - call both from Sema and from here
- const auto *BaseDRE =
- dyn_cast<DeclRefExpr>(Node.getBase()->IgnoreParenImpCasts());
- if (!BaseDRE)
+ if (const auto *BaseDRE =
+ dyn_cast<DeclRefExpr>(Node.getBase()->IgnoreParenImpCasts())) {
+ if (!BaseDRE->getDecl())
+ return false;
+ if (const auto *CATy = Finder->getASTContext().getAsConstantArrayType(
+ BaseDRE->getDecl()->getType())) {
+ if (const auto *IdxLit = dyn_cast<IntegerLiteral>(Node.getIdx())) {
+ const APInt ArrIdx = IdxLit->getValue();
+ // FIXME: ArrIdx.isNegative() we could immediately emit an error as
+ // that's a bug
+ if (ArrIdx.isNonNegative() &&
+ ArrIdx.getLimitedValue() < CATy->getLimitedSize())
+ return true;
+ }
+ }
+ }
+
+ if (const auto *BaseSL =
+ dyn_cast<StringLiteral>(Node.getBase()->IgnoreParenImpCasts())) {
+ if (const auto *CATy =
+ Finder->getASTContext().getAsConstantArrayType(BaseSL->getType())) {
+ if (const auto *IdxLit = dyn_cast<IntegerLiteral>(Node.getIdx())) {
+ const APInt ArrIdx = IdxLit->getValue();
+ // FIXME: ArrIdx.isNegative() we could immediately emit an error as
+ // that's a bug
+ if (ArrIdx.isNonNegative() &&
+ ArrIdx.getLimitedValue() < CATy->getLimitedSize())
+ return true;
+ }
+ }
+ }
+
+ return false;
+}
+
+AST_MATCHER(BinaryOperator, isSafePtrArithmetic) {
+ if (Node.getOpcode() != BinaryOperatorKind::BO_Add)
return false;
- if (!BaseDRE->getDecl())
+
+ const auto *LHSDRE = dyn_cast<DeclRefExpr>(Node.getLHS()->IgnoreImpCasts());
----------------
haoNoQ wrote:
I guess we might as well support the `"abc" + 3` case here. With the ultimate goal of ultimately supporting
```c++
static const char *const abc = "abc";
abc[3];
abc + 3;
```
https://github.com/llvm/llvm-project/pull/92432
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