[clang] [clang-tools-extra] [clang-tidy] Address false positives in misc-redundant-expression checker (PR #122841)

[via cfe-commits]

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@@ -847,11 +869,104 @@ static bool areExprsMacroAndNonMacro(const Expr *&LhsExpr,
   if (!LhsExpr || !RhsExpr)
     return false;
 
-  SourceLocation LhsLoc = LhsExpr->getExprLoc();
-  SourceLocation RhsLoc = RhsExpr->getExprLoc();
+  const SourceLocation LhsLoc = LhsExpr->getExprLoc();
+  const SourceLocation RhsLoc = RhsExpr->getExprLoc();
 
   return LhsLoc.isMacroID() != RhsLoc.isMacroID();
 }
+
+static bool areStringsSameIgnoreSpaces(const llvm::StringRef *Left,
+                                       const llvm::StringRef *Right) {
+  if (Left == Right)
+    return true;
+  if (Left->compare(*Right) == 0) {
+    return true;
+  }
+  // Do running index comparison
+  size_t LIdx = 0;
+  size_t RIdx = 0;
+  const char *LData = Left->data();
+  const char *RData = Right->data();
+  while (LIdx < Left->size() && RIdx < Right->size()) {
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earnol wrote:

I see. StringRef drop_front is calling substr version (https://llvm.org/doxygen/SimplifyLibCalls_8cpp_source.html#l00356) not doing string duplication, so this approach should have the same the same efficiency.

https://github.com/llvm/llvm-project/pull/122841