[clang] [Wunsafe-buffer-usage] Fix false positives in handling enums (PR #117370)

[Reid Kleckner via cfe-commits]

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@@ -463,6 +463,13 @@ AST_MATCHER(ArraySubscriptExpr, isSafeArraySubscript) {
       return true;
   }
 
+  // Array index wasn't an integer literal, let's see if it was an enum or
+  // something similar
+  const auto IntConst = Node.getIdx()->getIntegerConstantExpr(Finder->getASTContext());
+  if (IntConst && *IntConst > 0 && *IntConst < size) {
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rnk wrote:

Should it be `>= 0`?

https://github.com/llvm/llvm-project/pull/117370