[clang-tools-extra] [clang-tidy] avoid false positive when overload for bugprone-return-const-ref-from-parameter (PR #95434)

[Piotr Zegar via cfe-commits]

================
@@ -18,20 +17,87 @@ namespace clang::tidy::bugprone {
 void ReturnConstRefFromParameterCheck::registerMatchers(MatchFinder *Finder) {
   Finder->addMatcher(
       returnStmt(
-          hasReturnValue(declRefExpr(to(parmVarDecl(hasType(hasCanonicalType(
-              qualType(matchers::isReferenceToConst()).bind("type"))))))),
-          hasAncestor(functionDecl(hasReturnTypeLoc(
-              loc(qualType(hasCanonicalType(equalsBoundNode("type"))))))))
+          hasReturnValue(declRefExpr(
+              to(parmVarDecl(hasType(hasCanonicalType(
+                                 qualType(lValueReferenceType(pointee(
+                                              qualType(isConstQualified()))))
+                                     .bind("type"))))
+                     .bind("param")))),
+          hasAncestor(
+              functionDecl(hasReturnTypeLoc(loc(qualType(
+                               hasCanonicalType(equalsBoundNode("type"))))))
+                  .bind("func")))
           .bind("ret"),
       this);
 }
 
+static bool isSameTypeIgnoringConst(QualType A, QualType B) {
+  A = A.getCanonicalType();
+  B = B.getCanonicalType();
+  A.addConst();
+  B.addConst();
+  return A == B;
----------------
PiotrZSL wrote:

```suggestion
  return A.getCanonicalType().withConst() == B.getCanonicalType().withConst();
```

https://github.com/llvm/llvm-project/pull/95434