[clang-tools-extra] [clang-tidy] Adds readability-redundant-const check (PR #189733)

[Baranov Victor via cfe-commits]

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@@ -70,20 +70,56 @@ void RedundantConstCheck::registerMatchers(MatchFinder *Finder) {
       this);
 }
 
+static bool hasProblemSibling(const VarDecl *VD, SourceLocation ConstLoc,
+                              const SourceManager &SM, const LangOptions &LO) {
+  const SourceLocation Semi =
+      utils::lexer::findNextAnyTokenKind(ConstLoc, SM, LO, tok::semi);
+  if (Semi.isInvalid())
+    return false;
+
+  const SourceLocation Comma =
+      utils::lexer::findNextAnyTokenKind(ConstLoc, SM, LO, tok::comma);
+  if (Comma.isInvalid() || !SM.isBeforeInTranslationUnit(Comma, Semi))
+    return false;
+
+  for (Decl *D : VD->getDeclContext()->decls()) {
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vbvictor wrote:

I don't think we need to find all decls in declcontext for this case.
You can match `DeclStmt` class which incapsulates multiple decls and then check how much decls you have. If one you can process with normal path, if multiple then check that all decls are non-reference, non-etc... as you do with `Sib->getType()`.

So I think whole "hasProblemSibling" with lexing is not needed.

https://github.com/llvm/llvm-project/pull/189733