https://github.com/localspook updated https://github.com/llvm/llvm-project/pull/161574
>From 82c842a3e8f0f2e9dcfacca0eada9f6aeacd38d8 Mon Sep 17 00:00:00 2001 From: Victor Chernyakin <[email protected]> Date: Wed, 1 Oct 2025 18:35:35 +0000 Subject: [PATCH] [clang-tidy] Add new check: `readability-redundant-typename` --- .../clang-tidy/readability/CMakeLists.txt | 1 + .../readability/ReadabilityTidyModule.cpp | 3 + .../readability/RedundantTypenameCheck.cpp | 71 +++++++ .../readability/RedundantTypenameCheck.h | 37 ++++ clang-tools-extra/docs/ReleaseNotes.rst | 5 + .../docs/clang-tidy/checks/list.rst | 1 + .../checks/readability/redundant-typename.rst | 26 +++ .../readability/redundant-typename.cpp | 191 ++++++++++++++++++ 8 files changed, 335 insertions(+) create mode 100644 clang-tools-extra/clang-tidy/readability/RedundantTypenameCheck.cpp create mode 100644 clang-tools-extra/clang-tidy/readability/RedundantTypenameCheck.h create mode 100644 clang-tools-extra/docs/clang-tidy/checks/readability/redundant-typename.rst create mode 100644 clang-tools-extra/test/clang-tidy/checkers/readability/redundant-typename.cpp diff --git a/clang-tools-extra/clang-tidy/readability/CMakeLists.txt b/clang-tools-extra/clang-tidy/readability/CMakeLists.txt index 4b4c49d3b17d1..881672e36eb7d 100644 --- a/clang-tools-extra/clang-tidy/readability/CMakeLists.txt +++ b/clang-tools-extra/clang-tidy/readability/CMakeLists.txt @@ -48,6 +48,7 @@ add_clang_library(clangTidyReadabilityModule STATIC RedundantSmartptrGetCheck.cpp RedundantStringCStrCheck.cpp RedundantStringInitCheck.cpp + RedundantTypenameCheck.cpp ReferenceToConstructedTemporaryCheck.cpp SimplifyBooleanExprCheck.cpp SimplifySubscriptExprCheck.cpp diff --git a/clang-tools-extra/clang-tidy/readability/ReadabilityTidyModule.cpp b/clang-tools-extra/clang-tidy/readability/ReadabilityTidyModule.cpp index d01882dfc9daa..6ff64209a2b0e 100644 --- a/clang-tools-extra/clang-tidy/readability/ReadabilityTidyModule.cpp +++ b/clang-tools-extra/clang-tidy/readability/ReadabilityTidyModule.cpp @@ -51,6 +51,7 @@ #include "RedundantSmartptrGetCheck.h" #include "RedundantStringCStrCheck.h" #include "RedundantStringInitCheck.h" +#include "RedundantTypenameCheck.h" #include "ReferenceToConstructedTemporaryCheck.h" #include "SimplifyBooleanExprCheck.h" #include "SimplifySubscriptExprCheck.h" @@ -140,6 +141,8 @@ class ReadabilityModule : public ClangTidyModule { "readability-redundant-member-init"); CheckFactories.registerCheck<RedundantPreprocessorCheck>( "readability-redundant-preprocessor"); + CheckFactories.registerCheck<RedundantTypenameCheck>( + "readability-redundant-typename"); CheckFactories.registerCheck<ReferenceToConstructedTemporaryCheck>( "readability-reference-to-constructed-temporary"); CheckFactories.registerCheck<SimplifySubscriptExprCheck>( diff --git a/clang-tools-extra/clang-tidy/readability/RedundantTypenameCheck.cpp b/clang-tools-extra/clang-tidy/readability/RedundantTypenameCheck.cpp new file mode 100644 index 0000000000000..2861cbb19e534 --- /dev/null +++ b/clang-tools-extra/clang-tidy/readability/RedundantTypenameCheck.cpp @@ -0,0 +1,71 @@ +//===----------------------------------------------------------------------===// +// +// 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 "RedundantTypenameCheck.h" +#include "clang/AST/TypeLoc.h" +#include "clang/ASTMatchers/ASTMatchFinder.h" +#include "clang/ASTMatchers/ASTMatchers.h" +#include "clang/Basic/Diagnostic.h" +#include "clang/Sema/DeclSpec.h" + +using namespace clang::ast_matchers; +using namespace clang::ast_matchers::internal; + +namespace clang::tidy::readability { + +void RedundantTypenameCheck::registerMatchers(MatchFinder *Finder) { + // NOLINTNEXTLINE(readability-identifier-naming) + const VariadicDynCastAllOfMatcher<TypeLoc, TypedefTypeLoc> typedefTypeLoc; + Finder->addMatcher(typedefTypeLoc().bind("typeloc"), this); + + if (!getLangOpts().CPlusPlus20) + return; + + // NOLINTBEGIN(readability-identifier-naming) + const VariadicDynCastAllOfMatcher<Stmt, CXXNamedCastExpr> cxxNamedCastExpr; + const auto inImplicitTypenameContext = [&] { + return anyOf(hasParent(typedefNameDecl()), + hasParent(templateTypeParmDecl()), + hasParent(nonTypeTemplateParmDecl()), + hasParent(cxxNamedCastExpr()), hasParent(cxxNewExpr()), + hasParent(friendDecl()), hasParent(fieldDecl()), + hasParent(parmVarDecl(hasParent(expr(requiresExpr())))), + hasParent(parmVarDecl(hasParent(typeLoc(hasParent(namedDecl( + anyOf(cxxMethodDecl(), hasParent(friendDecl()), + functionDecl(has(nestedNameSpecifier()))))))))), + // Match return types. + hasParent(functionDecl(unless(cxxConversionDecl())))); + }; + // NOLINTEND(readability-identifier-naming) + Finder->addMatcher(typeLoc(inImplicitTypenameContext()).bind("typeloc"), + this); +} + +void RedundantTypenameCheck::check(const MatchFinder::MatchResult &Result) { + const SourceLocation TypenameKeywordLoc = [&] { + if (const auto *TTL = Result.Nodes.getNodeAs<TypedefTypeLoc>("typeloc")) + return TTL->getElaboratedKeywordLoc(); + + TypeLoc InnermostTypeLoc = *Result.Nodes.getNodeAs<TypeLoc>("typeloc"); + while (const TypeLoc Next = InnermostTypeLoc.getNextTypeLoc()) + InnermostTypeLoc = Next; + + if (const auto DNTL = InnermostTypeLoc.getAs<DependentNameTypeLoc>()) + return DNTL.getElaboratedKeywordLoc(); + + return SourceLocation(); + }(); + + if (!TypenameKeywordLoc.isValid()) + return; + + diag(TypenameKeywordLoc, "redundant 'typename'") + << FixItHint::CreateRemoval(TypenameKeywordLoc); +} + +} // namespace clang::tidy::readability diff --git a/clang-tools-extra/clang-tidy/readability/RedundantTypenameCheck.h b/clang-tools-extra/clang-tidy/readability/RedundantTypenameCheck.h new file mode 100644 index 0000000000000..2df5b38dcef0b --- /dev/null +++ b/clang-tools-extra/clang-tidy/readability/RedundantTypenameCheck.h @@ -0,0 +1,37 @@ + +//===----------------------------------------------------------------------===// +// +// 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 +// +//===----------------------------------------------------------------------===// + +#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_REDUNDANTTYPENAMECHECK_H +#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_REDUNDANTTYPENAMECHECK_H + +#include "../ClangTidyCheck.h" + +namespace clang::tidy::readability { + +/// Finds unnecessary uses of the `typename` keyword. +/// +/// For the user-facing documentation see: +/// http://clang.llvm.org/extra/clang-tidy/checks/readability/redundant-typename.html +class RedundantTypenameCheck : public ClangTidyCheck { +public: + RedundantTypenameCheck(StringRef Name, ClangTidyContext *Context) + : ClangTidyCheck(Name, Context) {} + bool isLanguageVersionSupported(const LangOptions &LangOpts) const override { + return LangOpts.CPlusPlus; + } + void registerMatchers(ast_matchers::MatchFinder *Finder) override; + void check(const ast_matchers::MatchFinder::MatchResult &Result) override; + std::optional<TraversalKind> getCheckTraversalKind() const override { + return TK_IgnoreUnlessSpelledInSource; + } +}; + +} // namespace clang::tidy::readability + +#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_REDUNDANTTYPENAMECHECK_H diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst index 3f403c42a168a..8f87864eff036 100644 --- a/clang-tools-extra/docs/ReleaseNotes.rst +++ b/clang-tools-extra/docs/ReleaseNotes.rst @@ -199,6 +199,11 @@ New checks Finds virtual function overrides with different visibility than the function in the base class. +- New :doc:`readability-redundant-typename + <clang-tidy/checks/readability/redundant-typename>` check. + + Finds unnecessary uses of the ``typename`` keyword. + New check aliases ^^^^^^^^^^^^^^^^^ diff --git a/clang-tools-extra/docs/clang-tidy/checks/list.rst b/clang-tools-extra/docs/clang-tidy/checks/list.rst index e06849c419389..2373edc3a2e96 100644 --- a/clang-tools-extra/docs/clang-tidy/checks/list.rst +++ b/clang-tools-extra/docs/clang-tidy/checks/list.rst @@ -408,6 +408,7 @@ Clang-Tidy Checks :doc:`readability-redundant-smartptr-get <readability/redundant-smartptr-get>`, "Yes" :doc:`readability-redundant-string-cstr <readability/redundant-string-cstr>`, "Yes" :doc:`readability-redundant-string-init <readability/redundant-string-init>`, "Yes" + :doc:`readability-redundant-typename <readability/redundant-typename>`, "Yes" :doc:`readability-reference-to-constructed-temporary <readability/reference-to-constructed-temporary>`, :doc:`readability-simplify-boolean-expr <readability/simplify-boolean-expr>`, "Yes" :doc:`readability-simplify-subscript-expr <readability/simplify-subscript-expr>`, "Yes" diff --git a/clang-tools-extra/docs/clang-tidy/checks/readability/redundant-typename.rst b/clang-tools-extra/docs/clang-tidy/checks/readability/redundant-typename.rst new file mode 100644 index 0000000000000..1c4040fbd12df --- /dev/null +++ b/clang-tools-extra/docs/clang-tidy/checks/readability/redundant-typename.rst @@ -0,0 +1,26 @@ +.. title:: clang-tidy - readability-redundant-typename + +readability-redundant-typename +============================== + +Finds unnecessary uses of the ``typename`` keyword. + +``typename`` is unnecessary in two cases. First, before non-dependent names: + +.. code-block:: c++ + + /* typename */ std::vector<int>::size_type size; + +And second, since C++20, before dependent names that appear in a context +where only a type is allowed (the following example shows just a few of them): + +.. code-block:: c++ + + template <typename T> + using trait = /* typename */ T::type; + + template <typename T> + struct S { + /* typename */ T::type variable; + /* typename */ T::type function(/* typename */ T::type); + }; diff --git a/clang-tools-extra/test/clang-tidy/checkers/readability/redundant-typename.cpp b/clang-tools-extra/test/clang-tidy/checkers/readability/redundant-typename.cpp new file mode 100644 index 0000000000000..3e77213564f89 --- /dev/null +++ b/clang-tools-extra/test/clang-tidy/checkers/readability/redundant-typename.cpp @@ -0,0 +1,191 @@ +// RUN: %check_clang_tidy -std=c++11,c++14,c++17 %s readability-redundant-typename %t \ +// RUN: -- -- -fno-delayed-template-parsing +// RUN: %check_clang_tidy -std=c++20-or-later -check-suffixes=,20 %s readability-redundant-typename %t \ +// RUN: -- -- -fno-delayed-template-parsing + +struct NotDependent { + using R = int; +}; + +auto f(typename NotDependent::R) + // CHECK-MESSAGES: :[[@LINE-1]]:8: warning: redundant 'typename' [readability-redundant-typename] + // CHECK-FIXES: auto f(NotDependent::R) + -> typename NotDependent::R + // CHECK-MESSAGES: :[[@LINE-1]]:6: warning: redundant 'typename' [readability-redundant-typename] + // CHECK-FIXES: -> NotDependent::R +{ + return typename NotDependent::R(); + // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: redundant 'typename' [readability-redundant-typename] + // return NotDependent::R(); +} + +template < + typename T, + typename T::R V, + // CHECK-MESSAGES-20: :[[@LINE-1]]:3: warning: redundant 'typename' [readability-redundant-typename] + // CHECK-FIXES-20: T::R V, + typename U = typename T::R + // CHECK-MESSAGES-20: :[[@LINE-1]]:16: warning: redundant 'typename' [readability-redundant-typename] + // CHECK-FIXES-20: typename U = T::R +> +auto f() -> typename T::R +// CHECK-MESSAGES-20: :[[@LINE-1]]:13: warning: redundant 'typename' [readability-redundant-typename] +// CHECK-FIXES-20: auto f() -> T::R +{ + static_cast<typename T::R>(0); + // CHECK-MESSAGES-20: :[[@LINE-1]]:15: warning: redundant 'typename' [readability-redundant-typename] + // CHECK-FIXES-20: static_cast<T::R>(0); + + dynamic_cast<typename T::R>(0); + // CHECK-MESSAGES-20: :[[@LINE-1]]:16: warning: redundant 'typename' [readability-redundant-typename] + // CHECK-FIXES-20: dynamic_cast<T::R>(0); + + reinterpret_cast<typename T::R>(0); + // CHECK-MESSAGES-20: :[[@LINE-1]]:20: warning: redundant 'typename' [readability-redundant-typename] + // CHECK-FIXES-20: reinterpret_cast<T::R>(0); + + const_cast<typename T::R>(0); + // CHECK-MESSAGES-20: :[[@LINE-1]]:14: warning: redundant 'typename' [readability-redundant-typename] + // CHECK-FIXES-20: const_cast<T::R>(0); + + static_cast<typename T::R&>(0); + // CHECK-MESSAGES-20: :[[@LINE-1]]:15: warning: redundant 'typename' [readability-redundant-typename] + // CHECK-FIXES-20: static_cast<T::R&>(0); + + dynamic_cast<typename T::R const volatile &&>(0); + // CHECK-MESSAGES-20: :[[@LINE-1]]:16: warning: redundant 'typename' [readability-redundant-typename] + // CHECK-FIXES-20: dynamic_cast<T::R const volatile &&>(0); + + reinterpret_cast<const typename T::template M<42>::R *>(0); + // CHECK-MESSAGES-20: :[[@LINE-1]]:26: warning: redundant 'typename' [readability-redundant-typename] + // CHECK-FIXES-20: reinterpret_cast<const T::template M<42>::R *>(0); + + const_cast<const typename T::R *const[100]>(0); + // CHECK-MESSAGES-20: :[[@LINE-1]]:20: warning: redundant 'typename' [readability-redundant-typename] + // CHECK-FIXES-20: const_cast<const T::R *const[100]>(0); + + (typename T::R)(0); + + alignof(typename T::R); + + new typename T::R(); + // CHECK-MESSAGES-20: :[[@LINE-1]]:7: warning: redundant 'typename' [readability-redundant-typename] + // CHECK-FIXES-20: new T::R(); + + // CHECK-MESSAGES-20: :[[@LINE+2]]:15: warning: redundant 'typename' [readability-redundant-typename] + // CHECK-FIXES-20: static_cast<decltype([] { + static_cast<typename decltype([] { + return typename T::R(); // Inner typename must stay. + })::R>(0); + + auto localFunctionDeclaration() -> typename T::R; + // CHECK-MESSAGES-20: :[[@LINE-1]]:38: warning: redundant 'typename' [readability-redundant-typename] + // CHECK-FIXES-20: auto localFunctionDeclaration() -> T::R; + + void (*PointerToFunction)(typename T::R); + void anotherLocalFunctionDeclaration(typename T::R); + + typename T::R DependentVar; + typename NotDependent::R NotDependentVar; + // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: redundant 'typename' [readability-redundant-typename] + // CHECK-FIXES: NotDependent::R NotDependentVar; + + return typename T::R(); +} + +template <typename T> +using trait = const typename T::R ****; +// CHECK-MESSAGES-20: :[[@LINE-1]]:21: warning: redundant 'typename' [readability-redundant-typename] +// CHECK-FIXES-20: using trait = const T::R ****; + +template <typename T> +trait<typename T::R> m(); + +#if __cplusplus >= 202002L + +template <typename T> +concept c = requires(typename T::R) { +// CHECK-MESSAGES-20: :[[@LINE-1]]:22: warning: redundant 'typename' [readability-redundant-typename] +// CHECK-FIXES-20: concept c = requires(T::R) { + typename T::R; +}; + +template <typename T> +requires c<typename T::R> +void b(); + +#endif // __cplusplus >= 202002L + +template <typename T, typename> +struct PartiallySpecializedType {}; + +template <typename T> +struct PartiallySpecializedType<T, typename T::R> {}; + +template <typename T> +auto v = typename T::type(); + +template <typename T> +typename T::R f(); +// CHECK-MESSAGES-20: :[[@LINE-1]]:1: warning: redundant 'typename' [readability-redundant-typename] +// CHECK-FIXES-20: T::R f(); + +template <typename T> +void n(typename T::R); + +namespace ns { + +template <typename T> +void f(typename T::R1, typename T::R2); + +} // namespace ns + +template <typename T> +void ns::f( + typename T::R1, + // CHECK-MESSAGES-20: :[[@LINE-1]]:3: warning: redundant 'typename' [readability-redundant-typename] + // CHECK-FIXES-20: T::R1, + typename T::R2 + // CHECK-MESSAGES-20: :[[@LINE-1]]:3: warning: redundant 'typename' [readability-redundant-typename] + // CHECK-FIXES-20: T::R2 +); + +template <typename T> +class A { +public: + friend typename T::R; + // CHECK-MESSAGES-20: :[[@LINE-1]]:10: warning: redundant 'typename' [readability-redundant-typename] + // CHECK-FIXES-20: friend T::R; + + typedef typename T::R a; + // CHECK-MESSAGES-20: :[[@LINE-1]]:11: warning: redundant 'typename' [readability-redundant-typename] + // CHECK-FIXES-20: typedef T::R a; + + const typename T::R typedef b; + // CHECK-MESSAGES-20: :[[@LINE-1]]:9: warning: redundant 'typename' [readability-redundant-typename] + // CHECK-FIXES-20: const T::R typedef b; + + typename T::R v; + // CHECK-MESSAGES-20: :[[@LINE-1]]:3: warning: redundant 'typename' [readability-redundant-typename] + // CHECK-FIXES-20: T::R v; + + typename T::R + // CHECK-MESSAGES-20: :[[@LINE-1]]:3: warning: redundant 'typename' [readability-redundant-typename] + // CHECK-FIXES-20: T::R + g(typename T::R) {} + // CHECK-MESSAGES-20: :[[@LINE-1]]:5: warning: redundant 'typename' [readability-redundant-typename] + // CHECK-FIXES-20: g(T::R) {} + + void h(typename T::R = typename T::R()) {} + // CHECK-MESSAGES-20: :[[@LINE-1]]:10: warning: redundant 'typename' [readability-redundant-typename] + // CHECK-FIXES-20: void h(T::R = typename T::R()) {} + + friend void k(typename T::R) {} + // CHECK-MESSAGES-20: :[[@LINE-1]]:17: warning: redundant 'typename' [readability-redundant-typename] + // CHECK-FIXES-20: friend void k(T::R) {} + + enum E1 : typename T::R {}; + enum class E2 : typename T::R {}; + operator typename T::R(); + void m() { this->operator typename T::R(); } +}; _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
