[clang-tools-extra] [clang-tidy] Enhance modernize-use-starts-ends-with to handle substr patterns (PR #116033)

[Nicolas van Kempen via cfe-commits]

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@@ -189,7 +203,54 @@ void UseStartsEndsWithCheck::check(const MatchFinder::MatchResult &Result) {
   if (ComparisonExpr->getBeginLoc().isMacroID())
     return;
 
-  const bool Neg = ComparisonExpr->getOpcode() == BO_NE;
+  bool Neg;
+  if (const auto *BO = llvm::dyn_cast<BinaryOperator>(ComparisonExpr)) {
+    Neg = BO->getOpcode() == BO_NE;
+  } else {
+    assert(llvm::isa<CXXOperatorCallExpr>(ComparisonExpr));
+    Neg = llvm::cast<CXXOperatorCallExpr>(ComparisonExpr)->getOperator() ==
+          OO_ExclaimEqual;
+  }
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nicovank wrote:

A possible risk of errors here is `RewrittenBinaryOperator` for C++20 and above: sometimes (always?) CXXOperatorCallExpr nodes `operator!=` are rewritten into `not operator==`. I'm not sure if this is something to worry about here, will have to read on it again.

https://github.com/llvm/llvm-project/pull/116033