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

[Ilya Biryukov via cfe-commits]

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@@ -1139,26 +1299,30 @@ class ArraySubscriptGadget : public WarningGadget {
   const ArraySubscriptExpr *ASE;
 
 public:
-  ArraySubscriptGadget(const MatchFinder::MatchResult &Result)
+  ArraySubscriptGadget(const MatchResult &Result)
       : WarningGadget(Kind::ArraySubscript),
-        ASE(Result.Nodes.getNodeAs<ArraySubscriptExpr>(ArraySubscrTag)) {}
+        ASE(Result.getNodeAs<ArraySubscriptExpr>(ArraySubscrTag)) {}
 
   static bool classof(const Gadget *G) {
     return G->getKind() == Kind::ArraySubscript;
   }
 
-  static Matcher matcher() {
-    // clang-format off
-      return stmt(arraySubscriptExpr(
-            hasBase(ignoringParenImpCasts(
-              anyOf(hasPointerType(), hasArrayType()))),
-            unless(anyOf(
-              isSafeArraySubscript(),
-              hasIndex(
-                  anyOf(integerLiteral(equals(0)), arrayInitIndexExpr())
-              )
-            ))).bind(ArraySubscrTag));
-    // clang-format on
+  static bool matches(const Stmt *S, const ASTContext &Ctx,
+                      MatchResult &Result) {
+    const auto *ASE = dyn_cast<ArraySubscriptExpr>(S);
+    if (!ASE)
+      return false;
+    const auto *const Base = ASE->getBase()->IgnoreParenImpCasts();
+    if (!hasPointerType(*Base) && !hasArrayType(*Base))
+      return false;
+    bool isSafeIndex =
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ilya-biryukov wrote:

NIT: should be in `UpperCamelCase`, i.e. `IsSafeIndex`

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