[clang-tools-extra] [clang-tidy] introduce a unused local non trival variable check (PR #76101)

[Piotr Zegar via cfe-commits]

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@@ -0,0 +1,92 @@
+//===--- UnusedLocalNonTrivialVariableCheck.cpp - clang-tidy --------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "UnusedLocalNonTrivialVariableCheck.h"
+#include "../utils/Matchers.h"
+#include "../utils/OptionsUtils.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/ASTTypeTraits.h"
+#include "clang/AST/Type.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/ASTMatchers/ASTMatchers.h"
+#include "clang/ASTMatchers/ASTMatchersMacros.h"
+
+using namespace clang::ast_matchers;
+using namespace clang::tidy::matchers;
+
+namespace clang::tidy::bugprone {
+
+namespace {
+static constexpr StringRef DefaultIncludeTypeRegex =
+    "::std::.*mutex;::std::future;::std::basic_string;::std::basic_regex;"
+    "::std::base_istringstream;::std::base_stringstream;::std::bitset;"
+    "::std::path";
+
+AST_MATCHER(VarDecl, isLocalVarDecl) { return Node.isLocalVarDecl(); }
+AST_MATCHER(VarDecl, isReferenced) { return Node.isReferenced(); }
+AST_MATCHER(Type, isReferenceType) { return Node.isReferenceType(); }
+AST_MATCHER(QualType, isTrivial) {
+  return Node.isTrivialType(Finder->getASTContext()) ||
+         Node.isTriviallyCopyableType(Finder->getASTContext());
+}
+} // namespace
+
+UnusedLocalNonTrivialVariableCheck::UnusedLocalNonTrivialVariableCheck(
+    StringRef Name, ClangTidyContext *Context)
+    : ClangTidyCheck(Name, Context),
+      IncludeTypes(utils::options::parseStringList(
+          Options.get("IncludeTypes", DefaultIncludeTypeRegex))),
+      ExcludeTypes(
+          utils::options::parseStringList(Options.get("ExcludeTypes", ""))) {}
+
+void UnusedLocalNonTrivialVariableCheck::storeOptions(
+    ClangTidyOptions::OptionMap &Opts) {
+  Options.store(Opts, "IncludeTypes",
+                utils::options::serializeStringList(IncludeTypes));
+  Options.store(Opts, "ExcludeTypes",
+                utils::options::serializeStringList(ExcludeTypes));
+}
+
+void UnusedLocalNonTrivialVariableCheck::registerMatchers(MatchFinder *Finder) {
+  if (IncludeTypes.empty())
+    return;
+
+  Finder->addMatcher(
+      varDecl(isLocalVarDecl(), unless(isReferenced()),
+              unless(isExpansionInSystemHeader()),
----------------
PiotrZSL wrote:

you can remove unless(isExpansionInSystemHeader()) as this should be handled in diffrent way for all checks in more generic way

https://github.com/llvm/llvm-project/pull/76101