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This check finds the usages of non-transparent functors and suggest to use the
transparent ones.
This check seems to be surprisingly slow though. Maybe because the amount of
typelocs in the source code? I did not have a chance to do a profiling yet, but
plan to do it later. Feel free to postpone the review until the profiling is
done.
Repository:
rL LLVM
https://reviews.llvm.org/D24894
Files:
clang-tidy/modernize/CMakeLists.txt
clang-tidy/modernize/ModernizeTidyModule.cpp
clang-tidy/modernize/UseTransparentFunctorsCheck.cpp
clang-tidy/modernize/UseTransparentFunctorsCheck.h
docs/ReleaseNotes.rst
docs/clang-tidy/checks/list.rst
docs/clang-tidy/checks/modernize-use-transparent-functors.rst
test/clang-tidy/modernize-use-transparent-functors.cpp
Index: test/clang-tidy/modernize-use-transparent-functors.cpp
===================================================================
--- /dev/null
+++ test/clang-tidy/modernize-use-transparent-functors.cpp
@@ -0,0 +1,100 @@
+// RUN: %check_clang_tidy %s modernize-use-transparent-functors %t -- -- -std=c++14
+
+namespace std {
+template<class T>
+struct remove_reference;
+
+template <class T>
+constexpr T &&forward(typename std::remove_reference<T>::type &t);
+
+template <class T>
+constexpr T &&forward(typename std::remove_reference<T>::type &&t);
+
+template <typename T = void>
+struct plus {
+ constexpr T operator()(const T &Lhs, const T &Rhs) const;
+};
+
+template <>
+struct plus<void> {
+ template <typename T, typename U>
+ constexpr auto operator()(T &&Lhs, U &&Rhs) const ->
+ decltype(forward<T>(Lhs) + forward<U>(Rhs));
+};
+
+template <typename T = void>
+struct less {
+ constexpr bool operator()(const T &Lhs, const T &Rhs) const;
+};
+
+template <>
+struct less<void> {
+ template <typename T, typename U>
+ constexpr bool operator()(T &&Lhs, U &&Rhs) const;
+};
+
+template <typename T = void>
+struct logical_not {
+ constexpr bool operator()(const T &Arg) const;
+};
+
+template <>
+struct logical_not<void> {
+ template <typename T>
+ constexpr bool operator()(T &&Arg) const;
+};
+
+template <typename T>
+class allocator;
+
+template <
+ class Key,
+ class Compare = std::less<>,
+ class Allocator = std::allocator<Key>>
+class set {};
+
+template <class InputIt, class UnaryPredicate>
+InputIt find_if(InputIt first, InputIt last,
+ UnaryPredicate p);
+
+template <class RandomIt, class Compare>
+void sort(RandomIt first, RandomIt last, Compare comp);
+
+class iterator {};
+class string {};
+}
+
+int main() {
+ using std::set;
+ using std::less;
+ std::set<int, std::less<int>> s;
+ // CHECK-MESSAGES: :[[@LINE-1]]:17: warning: prefer transparent functors [modernize-use-transparent-functors]
+ // CHECK-FIXES: {{^}} std::set<int, std::less<>> s;{{$}}
+ set<int, std::less<int>> s2;
+ // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: prefer transparent functors
+ // CHECK-FIXES: {{^}} set<int, std::less<>> s2;{{$}}
+ set<int, less<int>> s3;
+ // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: prefer transparent functors
+ // CHECK-FIXES: {{^}} set<int, less<>> s3;{{$}}
+ std::set<int, std::less<>> s4;
+ std::set<char *, std::less<std::string>> s5;
+ std::set<set<int, less<int>>, std::less<>> s6;
+ // CHECK-MESSAGES: :[[@LINE-1]]:21: warning: prefer transparent functors
+ // CHECK-FIXES: {{^}} std::set<set<int, less<>>, std::less<>> s6;{{$}}
+ std::iterator begin, end;
+ sort(begin, end, std::less<int>());
+ // CHECK-MESSAGES: :[[@LINE-1]]:20: warning: prefer transparent functors
+ std::sort(begin, end, std::less<>());
+ find_if(begin, end, std::logical_not<bool>());
+ // CHECK-MESSAGES: :[[@LINE-1]]:23: warning: prefer transparent functors
+ std::find_if(begin, end, std::logical_not<>());
+ using my_set = std::set<int, std::less<int>>;
+ // CHECK-MESSAGES: :[[@LINE-1]]:32: warning: prefer transparent functors
+ // CHECK-FIXES: {{^}} using my_set = std::set<int, std::less<>>;{{$}}
+ using my_set2 = std::set<char*, std::less<std::string>>;
+ using my_less = std::less<std::string>;
+ find_if(begin, end, my_less());
+ // CHECK-MESSAGES: :[[@LINE-1]]:23: warning: prefer transparent functors
+}
+
+
Index: docs/clang-tidy/checks/modernize-use-transparent-functors.rst
===================================================================
--- /dev/null
+++ docs/clang-tidy/checks/modernize-use-transparent-functors.rst
@@ -0,0 +1,24 @@
+.. title:: clang-tidy - modernize-use-transparent-functors
+
+modernize-use-transparent-functors
+==================================
+
+Prefer transparent functors to non-transparent ones. Using transparent functors
+the type does not need to be repeated. The code is easier to read, maintain and
+less prone to errors. It not possible to introduce unwanted conversions.
+
+ .. code-block:: c++
+
+ // Non-transparent functor
+ std::map<int, std::string, std::greater<int>> s;
+
+ // Transparent functor.
+ std::map<int, std::string, std::greater<>> s;
+
+It is not always a safe transformation though. The following case will be
+untouched to preserve the semantics.
+
+ .. code-block:: c++
+
+ // Non-transparent functor
+ std::map<const char *, std::string, std::greater<std::string>> s;
Index: docs/clang-tidy/checks/list.rst
===================================================================
--- docs/clang-tidy/checks/list.rst
+++ docs/clang-tidy/checks/list.rst
@@ -111,6 +111,7 @@
modernize-use-emplace
modernize-use-nullptr
modernize-use-override
+ modernize-use-transparent-functors
modernize-use-using
mpi-buffer-deref
mpi-type-mismatch
Index: docs/ReleaseNotes.rst
===================================================================
--- docs/ReleaseNotes.rst
+++ docs/ReleaseNotes.rst
@@ -79,6 +79,11 @@
Warns if an object is used after it has been moved, without an intervening
reinitialization.
+- New `modernize-use-transparent-functors
+ <http://clang.llvm.org/extra/clang-tidy/checks/modernize-use-transparent-functors.html>`_ check
+
+ Replaces uses of non-transparent functors with transparent ones where applicable.
+
- New `mpi-buffer-deref
<http://clang.llvm.org/extra/clang-tidy/checks/mpi-buffer-deref.html>`_ check
Index: clang-tidy/modernize/UseTransparentFunctorsCheck.h
===================================================================
--- /dev/null
+++ clang-tidy/modernize/UseTransparentFunctorsCheck.h
@@ -0,0 +1,35 @@
+//===--- UseTransparentFunctorsCheck.h - clang-tidy--------------*- C++ -*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MODERNIZE_USE_TRANSPARENT_FUNCTORS_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MODERNIZE_USE_TRANSPARENT_FUNCTORS_H
+
+#include "../ClangTidy.h"
+
+namespace clang {
+namespace tidy {
+namespace modernize {
+
+/// Prefer using transparent functors to non-transparent ones.
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/modernize-use-transparent-functors.html
+class UseTransparentFunctorsCheck : public ClangTidyCheck {
+public:
+ UseTransparentFunctorsCheck(StringRef Name, ClangTidyContext *Context)
+ : ClangTidyCheck(Name, Context) {}
+ void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+ void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+};
+
+} // namespace modernize
+} // namespace tidy
+} // namespace clang
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MODERNIZE_USE_TRANSPARENT_FUNCTORS_H
Index: clang-tidy/modernize/UseTransparentFunctorsCheck.cpp
===================================================================
--- /dev/null
+++ clang-tidy/modernize/UseTransparentFunctorsCheck.cpp
@@ -0,0 +1,99 @@
+//===--- UseTransparentFunctorsCheck.cpp - clang-tidy----------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "UseTransparentFunctorsCheck.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang {
+namespace tidy {
+namespace modernize {
+
+void UseTransparentFunctorsCheck::registerMatchers(MatchFinder *Finder) {
+ if (!getLangOpts().CPlusPlus14)
+ return;
+
+ const auto TransparentFunctors = classTemplateSpecializationDecl(
+ unless(hasAnyTemplateArgument(refersToType(voidType()))),
+ hasAnyName("::std::plus", "::std::minus", "::std::multiplies",
+ "::std::divides", "::std::modulus", "::std::negate",
+ "::std::equal_to", "::std::not_equal_to", "::std::greater",
+ "::std::less", "::std::greater_equal", "::std::less_equal",
+ "::std::logical_and", "::std::logical_or",
+ "::std::logical_not", "::std::bit_and", "::std::bit_or",
+ "::std::bit_xor", "::std::bit_not"));
+
+ // Non-transparent functor mentioned as a template parameter. FIXIT.
+ Finder->addMatcher(
+ loc(qualType(
+ unless(elaboratedType()),
+ hasDeclaration(classTemplateSpecializationDecl(
+ unless(hasAnyTemplateArgument(templateArgument(refersToType(
+ qualType(pointsTo(qualType(isAnyCharacter()))))))),
+ hasAnyTemplateArgument(
+ templateArgument(refersToType(qualType(hasDeclaration(
+ TransparentFunctors))))
+ .bind("Functor"))))))
+ .bind("FunctorParentLoc"),
+ this);
+
+ // Non-transparent functor constructed. No FIXIT. There is no easy way
+ // to rule out the problematic char* vs string case.
+ Finder->addMatcher(cxxConstructExpr(hasDeclaration(cxxMethodDecl(
+ ofClass(TransparentFunctors))),
+ unless(isInTemplateInstantiation()))
+ .bind("FuncInst"),
+ this);
+}
+
+void UseTransparentFunctorsCheck::check(
+ const MatchFinder::MatchResult &Result) {
+ if (const auto *FuncInst =
+ Result.Nodes.getNodeAs<CXXConstructExpr>("FuncInst")) {
+ diag(FuncInst->getLocStart(), "prefer transparent functors");
+ return;
+ }
+
+ const auto *Functor = Result.Nodes.getNodeAs<TemplateArgument>("Functor");
+ const auto FunctorParentLoc =
+ Result.Nodes.getNodeAs<TypeLoc>("FunctorParentLoc")
+ ->castAs<TemplateSpecializationTypeLoc>();
+
+ unsigned ArgNum = 0;
+ for (; ArgNum < FunctorParentLoc.getNumArgs(); ++ArgNum) {
+ if (FunctorParentLoc.getArgLoc(ArgNum)
+ .getArgument()
+ .getAsType()
+ .getDesugaredType(*Result.Context) == Functor->getAsType()) {
+ break;
+ }
+ }
+ assert(ArgNum < FunctorParentLoc.getNumArgs());
+ TemplateArgumentLoc FunctorLoc = FunctorParentLoc.getArgLoc(ArgNum);
+ auto FunctorTypeLoc = FunctorLoc.getTypeSourceInfo()
+ ->getTypeLoc()
+ .getAs<TemplateSpecializationTypeLoc>();
+ if (FunctorTypeLoc.isNull()) {
+ FunctorTypeLoc = FunctorLoc.getTypeSourceInfo()
+ ->getTypeLoc()
+ .getAs<ElaboratedTypeLoc>()
+ .getNamedTypeLoc()
+ .castAs<TemplateSpecializationTypeLoc>();
+ }
+ SourceLocation ReportLoc = FunctorLoc.getLocation();
+
+ diag(ReportLoc, "prefer transparent functors")
+ << FixItHint::CreateRemoval(FunctorTypeLoc.getArgLoc(0).getSourceRange());
+}
+
+} // namespace modernize
+} // namespace tidy
+} // namespace clang
Index: clang-tidy/modernize/ModernizeTidyModule.cpp
===================================================================
--- clang-tidy/modernize/ModernizeTidyModule.cpp
+++ clang-tidy/modernize/ModernizeTidyModule.cpp
@@ -26,6 +26,7 @@
#include "UseEmplaceCheck.h"
#include "UseNullptrCheck.h"
#include "UseOverrideCheck.h"
+#include "UseTransparentFunctorsCheck.h"
#include "UseUsingCheck.h"
using namespace clang::ast_matchers;
@@ -59,6 +60,8 @@
CheckFactories.registerCheck<UseEmplaceCheck>("modernize-use-emplace");
CheckFactories.registerCheck<UseNullptrCheck>("modernize-use-nullptr");
CheckFactories.registerCheck<UseOverrideCheck>("modernize-use-override");
+ CheckFactories.registerCheck<UseTransparentFunctorsCheck>(
+ "modernize-use-transparent-functors");
CheckFactories.registerCheck<UseUsingCheck>("modernize-use-using");
}
Index: clang-tidy/modernize/CMakeLists.txt
===================================================================
--- clang-tidy/modernize/CMakeLists.txt
+++ clang-tidy/modernize/CMakeLists.txt
@@ -20,6 +20,7 @@
UseEmplaceCheck.cpp
UseNullptrCheck.cpp
UseOverrideCheck.cpp
+ UseTransparentFunctorsCheck.cpp
UseUsingCheck.cpp
LINK_LIBS
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