[clang-tidy] Fix false positive for cppcoreguidelines-init-variables

[njames93]

Summary

Fixes False positive for cppcoreguidelines-init-variables in range based for loop in template function

[njames93]

clang-tools-extra/clang-tidy/cppcoreguidelines/InitVariablesCheck.cpp

37

No point checking if its a template definition or not. According to the standard it's not possible to have a for range statement where the loop variable isn't initialized.

[merge_guards_bot]

Unit tests: pass. 62371 tests passed, 0 failed and 839 were skipped.

clang-tidy: pass.

clang-format: pass.

Build artifacts: diff.json, clang-tidy.txt, clang-format.patch, CMakeCache.txt, console-log.txt, test-results.xml

Pre-merge checks is in beta. Report issue. Please join beta or enable it for your project.

[aaron.ballman]

LGTM!

clang-tools-extra/clang-tidy/cppcoreguidelines/InitVariablesCheck.cpp

 InitVariablesCheck::InitVariablesCheck(StringRef Name,
                                        ClangTidyContext *Context)
     : ClangTidyCheck(Name, Context),
       IncludeStyle(utils::IncludeSorter::parseIncludeStyle(
           Options.getLocalOrGlobal("IncludeStyle", "llvm"))),
       MathHeader(Options.get("MathHeader", "math.h")) {}
 
 void InitVariablesCheck::registerMatchers(MatchFinder *Finder) {
-  Finder->addMatcher(varDecl(unless(hasInitializer(anything())),
-                             unless(isInstantiated()), isLocalVarDecl(),
-                             unless(isStaticLocal()), isDefinition())
-                         .bind("vardecl"),
-                     this);
+  std::string BadDecl = "badDecl";
+  Finder->addMatcher(
+      varDecl(unless(hasInitializer(anything())), unless(isInstantiated()),
+              isLocalVarDecl(), unless(isStaticLocal()), isDefinition(),
+              optionally(hasParent(declStmt(hasParent(
+                  cxxForRangeStmt(hasLoopVariable(varDecl().bind(BadDecl))))))),
+              unless(equalsBoundNode(BadDecl)))
 }
 
 void InitVariablesCheck::registerPPCallbacks(const SourceManager &SM,
                                              Preprocessor *PP,
                                              Preprocessor *ModuleExpanderPP) {
   IncludeInserter =
       std::make_unique<utils::IncludeInserter>(SM, getLangOpts(), IncludeStyle);
   PP->addPPCallbacks(IncludeInserter->CreatePPCallbacks());

clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines-init-variables.cpp

void init_unit_tests() {
 
   UnusedStruct u;
 
   static int does_not_need_an_initializer;
   extern int does_not_need_an_initializer2;
   int parens(42);
   int braces{42};
 }
+
+template <typename RANGE>
+void f(RANGE r) {
+  for (char c : r) {
+  }
+}