[clang] [Clang] Optimize -Wunsafe-buffer-usage. (PR #125492)

[Ilya Biryukov via cfe-commits]

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@@ -1636,24 +1914,33 @@ class ULCArraySubscriptGadget : public FixableGadget {
   const ArraySubscriptExpr *Node;
 
 public:
-  ULCArraySubscriptGadget(const MatchFinder::MatchResult &Result)
+  ULCArraySubscriptGadget(const MatchResult &Result)
       : FixableGadget(Kind::ULCArraySubscript),
-        Node(Result.Nodes.getNodeAs<ArraySubscriptExpr>(ULCArraySubscriptTag)) {
+        Node(Result.getNodeAs<ArraySubscriptExpr>(ULCArraySubscriptTag)) {
     assert(Node != nullptr && "Expecting a non-null matching result");
   }
 
   static bool classof(const Gadget *G) {
     return G->getKind() == Kind::ULCArraySubscript;
   }
 
-  static Matcher matcher() {
-    auto ArrayOrPtr = anyOf(hasPointerType(), hasArrayType());
-    auto BaseIsArrayOrPtrDRE = hasBase(
-        ignoringParenImpCasts(declRefExpr(ArrayOrPtr, toSupportedVariable())));
-    auto Target =
-        arraySubscriptExpr(BaseIsArrayOrPtrDRE).bind(ULCArraySubscriptTag);
-
-    return expr(isInUnspecifiedLvalueContext(Target));
+  static bool matches(const Stmt *S, llvm::SmallVector<MatchResult> &Results) {
+    bool Found = false;
+    findStmtsInUnspecifiedLvalueContext(S, [&Found, &Results](const Expr *E) {
+      const auto *ASE = dyn_cast<ArraySubscriptExpr>(E);
+      if (!ASE)
+        return;
+      const auto *DRE =
+          dyn_cast<DeclRefExpr>(ASE->getBase()->IgnoreParenImpCasts());
+      if (!DRE || (!hasPointerType(*DRE) && !hasArrayType(*DRE)) ||
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ilya-biryukov wrote:

NIT: maybe replace with ` !(hasPointerType(*DRE) || hasArrayType(*DRE))`? it has less negations and (IMO) a little easier to follow

https://github.com/llvm/llvm-project/pull/125492