[clang-tidy] Simplify default member init check

clang-tools-extra/clang-tidy/modernize/UseDefaultMemberInitCheck.h

 public:
   UseDefaultMemberInitCheck(StringRef Name, ClangTidyContext *Context);
   bool isLanguageVersionSupported(const LangOptions &LangOpts) const override {
     return LangOpts.CPlusPlus11;
   }
   void storeOptions(ClangTidyOptions::OptionMap &Opts) override;
   void registerMatchers(ast_matchers::MatchFinder *Finder) override;
   void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+  llvm::Optional<TraversalKind> getCheckTraversalKind() const override {
+    return TK_IgnoreUnlessSpelledInSource;
+  }
 
 private:
   void checkDefaultInit(const ast_matchers::MatchFinder::MatchResult &Result,
                         const CXXCtorInitializer *Init);
   void checkExistingInit(const ast_matchers::MatchFinder::MatchResult &Result,
                          const CXXCtorInitializer *Init);
 
   const bool UseAssignment;
   const bool IgnoreMacros;
 };
 
 } // namespace modernize
 } // namespace tidy
 } // namespace clang
 
 #endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MODERNIZE_USE_DEFAULT_MEMBER_INIT_H

clang-tools-extra/clang-tidy/modernize/UseDefaultMemberInitCheck.cpp

auto InitBase =
                           hasUnaryOperand(integerLiteral())),
             floatLiteral(),
             unaryOperator(hasAnyOperatorName("+", "-"),
                           hasUnaryOperand(floatLiteral())),
             cxxBoolLiteral(), cxxNullPtrLiteralExpr(), implicitValueInitExpr(),
             declRefExpr(to(enumConstantDecl())));
 
   auto Init =
-      anyOf(initListExpr(anyOf(
-                allOf(initCountIs(1), hasInit(0, ignoringImplicit(InitBase))),
+      anyOf(initListExpr(anyOf(allOf(initCountIs(1), hasInit(0, InitBase)),
                                initCountIs(0))),
             InitBase);
 
   Finder->addMatcher(
       cxxConstructorDecl(
-          isDefaultConstructor(), unless(isInstantiated()),
+          isDefaultConstructor(),
           forEachConstructorInitializer(
               cxxCtorInitializer(
                   forField(unless(anyOf(getLangOpts().CPlusPlus20
                                             ? unless(anything())
                                             : isBitField(),
                                         hasInClassInitializer(anything()),
                                         hasParent(recordDecl(isUnion()))))),
-                  isWritten(), withInitializer(ignoringImplicit(Init)))
+                  withInitializer(Init))
                   .bind("default"))),
       this);
 
   Finder->addMatcher(
-      cxxConstructorDecl(
-          unless(ast_matchers::isTemplateInstantiation()),
-          forEachConstructorInitializer(
-              cxxCtorInitializer(forField(hasInClassInitializer(anything())),
-                                 isWritten(),
-                                 withInitializer(ignoringImplicit(Init)))
-                  .bind("existing"))),
+      cxxConstructorDecl(forEachConstructorInitializer(
+                             withInitializer(Init))
       this);
 }
 
 void UseDefaultMemberInitCheck::check(const MatchFinder::MatchResult &Result) {
   if (const auto *Default =
           Result.Nodes.getNodeAs<CXXCtorInitializer>("default"))
     checkDefaultInit(Result, Default);
   else if (const auto *Existing =