Index: clang-tidy/misc/UnusedUsingDeclsCheck.cpp =================================================================== --- clang-tidy/misc/UnusedUsingDeclsCheck.cpp +++ clang-tidy/misc/UnusedUsingDeclsCheck.cpp @@ -37,6 +37,9 @@ Finder->addMatcher(declRefExpr().bind("used"), this); Finder->addMatcher(callExpr(callee(unresolvedLookupExpr().bind("used"))), this); + Finder->addMatcher( + callExpr(hasDeclaration(functionDecl(isInstantiated()).bind("used"))), + this); } void UnusedUsingDeclsCheck::check(const MatchFinder::MatchResult &Result) { @@ -71,16 +74,48 @@ Contexts.push_back(Context); return; } - // Mark using declarations as used by setting FoundDecls' value to zero. As // the AST is walked in order, usages are only marked after a the // corresponding using declaration has been found. // FIXME: This currently doesn't look at whether the type reference is // actually found with the help of the using declaration. if (const auto *Used = Result.Nodes.getNodeAs("used")) { - if (const auto *Specialization = - dyn_cast(Used)) + if (const auto *FD = dyn_cast(Used)) { + // There is no straightforward way to match template arguments in a + // function call/class member call expression, so we iterate all template + // specializations of a function template to mark all template arguments + // as used. + // + // Find template argument that is provided for a template template + // parameter, e.g: + // + // template class A { T t; }; + // B.func(); + // + // Find template class A in B::func template argument. + if (const auto* TemplateArgs = FD->getTemplateSpecializationArgs()) { + for (size_t i = 0; i < TemplateArgs->size(); ++i) { + const auto& TemplateArg = TemplateArgs->get(i); + switch (TemplateArg.getKind()) { + case TemplateArgument::Template: + // Remove class template declaration. + removeFromFoundDecls( + TemplateArg.getAsTemplate().getAsTemplateDecl()); + break; + case TemplateArgument::Declaration: + // Remove function template declaration. + if (auto *FDT = dyn_cast(TemplateArg.getAsDecl())) + removeFromFoundDecls(FDT->getPrimaryTemplate()); + break; + default: + break; + } + } + } + } else if (const auto *Specialization = + dyn_cast(Used)) { Used = Specialization->getSpecializedTemplate(); + } removeFromFoundDecls(Used); return; } @@ -109,6 +144,8 @@ } void UnusedUsingDeclsCheck::removeFromFoundDecls(const Decl *D) { + if (!D) + return; // FIXME: Currently, we don't handle the using-decls being used in different // scopes (such as different namespaces, different functions). Instead of // giving an incorrect message, we mark all of them as used. Index: test/clang-tidy/Inputs/unused-using-decls.h =================================================================== --- /dev/null +++ test/clang-tidy/Inputs/unused-using-decls.h @@ -0,0 +1,11 @@ +class MyClass { +public: + template