diff --git a/clang-tools-extra/clang-tidy/misc/UnusedUsingDeclsCheck.cpp b/clang-tools-extra/clang-tidy/misc/UnusedUsingDeclsCheck.cpp index dafd32ed41c7eb..96055c29ffa8ea 100644 --- a/clang-tools-extra/clang-tidy/misc/UnusedUsingDeclsCheck.cpp +++ b/clang-tools-extra/clang-tidy/misc/UnusedUsingDeclsCheck.cpp @@ -38,6 +38,13 @@ AST_POLYMORPHIC_MATCHER_P( *Builder = std::move(Result); return Matched; } + +AST_MATCHER_P(DeducedTemplateSpecializationType, refsToTemplatedDecl, + clang::ast_matchers::internal::Matcher, DeclMatcher) { + if (const auto *TD = Node.getTemplateName().getAsTemplateDecl()) + return DeclMatcher.matches(*TD, Finder, Builder); + return false; +} } // namespace // A function that helps to tell whether a TargetDecl in a UsingDecl will be @@ -56,6 +63,9 @@ void UnusedUsingDeclsCheck::registerMatchers(MatchFinder *Finder) { Finder->addMatcher(loc(enumType(DeclMatcher)), this); Finder->addMatcher(loc(recordType(DeclMatcher)), this); Finder->addMatcher(loc(templateSpecializationType(DeclMatcher)), this); + Finder->addMatcher(loc(deducedTemplateSpecializationType( + refsToTemplatedDecl(namedDecl().bind("used")))), + this); Finder->addMatcher(declRefExpr().bind("used"), this); Finder->addMatcher(callExpr(callee(unresolvedLookupExpr().bind("used"))), this); diff --git a/clang-tools-extra/test/clang-tidy/checkers/misc-unused-using-decls-cxx17.cpp b/clang-tools-extra/test/clang-tidy/checkers/misc-unused-using-decls-cxx17.cpp new file mode 100644 index 00000000000000..ca17e44be8e68d --- /dev/null +++ b/clang-tools-extra/test/clang-tidy/checkers/misc-unused-using-decls-cxx17.cpp @@ -0,0 +1,30 @@ +// RUN: %check_clang_tidy -std=c++17-or-later %s misc-unused-using-decls %t -- -- -fno-delayed-template-parsing -isystem %S/Inputs/ + +namespace ns { + +template class Foo { +public: + Foo(T); +}; +// Deduction guide (CTAD) +template Foo(T t) -> Foo; + +template class Bar { +public: + Bar(T); +}; + +template class Unused {}; + +} // namespace ns + +using ns::Bar; +using ns::Foo; +using ns::Unused; // Unused +// CHECK-MESSAGES: :[[@LINE-1]]:11: warning: using decl 'Unused' is unused +// CHECK-FIXES: {{^}}// Unused + +void f() { + Foo(123); + Bar(1); +}