llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT--> @llvm/pr-subscribers-clang-tidy Author: St. Muench (stmuench) <details> <summary>Changes</summary> So far, the clang-tidy check `modernize-avoid-c-arrays` also diagnosed array types for type template parameters even though no actual array type got written there but it got deduced to one. In such case, there is nothing a developer can do at that location to fix the diagnostic. Since actually, the location where the template got instantiated would have to be adjusted. And this is in most cases some totally distant code where implementers of a template do not have access to. Also adding suppressions to the declaration of the template is not an option since that would clutter the code unnecessarily and is in many cases also simply not possible. Hence, we propose to not diagnose any occurrence of an array type in an implicit instantiation of a template but rather at the point where template arguments involve array types. --- Full diff: https://github.com/llvm/llvm-project/pull/132924.diff 3 Files Affected: - (modified) clang-tools-extra/clang-tidy/modernize/AvoidCArraysCheck.cpp (+56-4) - (modified) clang-tools-extra/test/clang-tidy/checkers/modernize/avoid-c-arrays-ignores-strings.cpp (+12) - (modified) clang-tools-extra/test/clang-tidy/checkers/modernize/avoid-c-arrays.cpp (+159) ``````````diff diff --git a/clang-tools-extra/clang-tidy/modernize/AvoidCArraysCheck.cpp b/clang-tools-extra/clang-tidy/modernize/AvoidCArraysCheck.cpp index 0804aa76d953c..e26b8cf885ea3 100644 --- a/clang-tools-extra/clang-tidy/modernize/AvoidCArraysCheck.cpp +++ b/clang-tools-extra/clang-tidy/modernize/AvoidCArraysCheck.cpp @@ -39,6 +39,30 @@ AST_MATCHER(clang::ParmVarDecl, isArgvOfMain) { return FD ? FD->isMain() : false; } +bool isWithinImplicitTemplateInstantiation(const TypeLoc *ArrayType, + ASTContext *Context) { + const auto IsImplicitTemplateInstantiation = [](const auto *Node) { + return (Node != nullptr) && + (Node->getTemplateSpecializationKind() == TSK_ImplicitInstantiation); + }; + + auto ParentNodes = Context->getParents(*ArrayType); + while (!ParentNodes.empty()) { + const auto &ParentNode = ParentNodes[0]; + if (IsImplicitTemplateInstantiation( + ParentNode.template get<clang::CXXRecordDecl>()) || + IsImplicitTemplateInstantiation( + ParentNode.template get<clang::FunctionDecl>()) || + IsImplicitTemplateInstantiation( + ParentNode.template get<clang::VarDecl>())) { + return true; + } + ParentNodes = Context->getParents(ParentNode); + } + + return false; +} + } // namespace AvoidCArraysCheck::AvoidCArraysCheck(StringRef Name, ClangTidyContext *Context) @@ -70,18 +94,45 @@ void AvoidCArraysCheck::registerMatchers(MatchFinder *Finder) { std::move(IgnoreStringArrayIfNeededMatcher)) .bind("typeloc"), this); + + Finder->addMatcher(templateArgumentLoc(hasTypeLoc( + loc(arrayType()).bind("typeloc_in_template_arg"))), + this); } void AvoidCArraysCheck::check(const MatchFinder::MatchResult &Result) { - const auto *ArrayType = Result.Nodes.getNodeAs<TypeLoc>("typeloc"); + clang::TypeLoc ArrayTypeLoc{}; + + if (const auto *ArrayType = Result.Nodes.getNodeAs<TypeLoc>("typeloc"); + ArrayType != nullptr && + not(isWithinImplicitTemplateInstantiation(ArrayType, Result.Context))) { + ArrayTypeLoc = *ArrayType; + } + + if (const auto *ArrayTypeInTemplateArg = + Result.Nodes.getNodeAs<TypeLoc>("typeloc_in_template_arg"); + ArrayTypeInTemplateArg != nullptr) { + if (ArrayTypeInTemplateArg->getSourceRange() != + ArrayTypeInTemplateArg->getLocalSourceRange()) { + // only in case the above condition is fulfilled, we matched a written + // array type and not a template type parameter which got deduced to one + ArrayTypeLoc = *ArrayTypeInTemplateArg; + } + } + + // check whether the match result is a real array type (based on above checks) + if (ArrayTypeLoc.isNull()) { + return; + } + const bool IsInParam = Result.Nodes.getNodeAs<ParmVarDecl>("param_decl") != nullptr; - const bool IsVLA = ArrayType->getTypePtr()->isVariableArrayType(); + const bool IsVLA = ArrayTypeLoc.getTypePtr()->isVariableArrayType(); enum class RecommendType { Array, Vector, Span }; llvm::SmallVector<const char *> RecommendTypes{}; if (IsVLA) { RecommendTypes.push_back("'std::vector'"); - } else if (ArrayType->getTypePtr()->isIncompleteArrayType() && IsInParam) { + } else if (ArrayTypeLoc.getTypePtr()->isIncompleteArrayType() && IsInParam) { // in function parameter, we also don't know the size of // IncompleteArrayType. if (Result.Context->getLangOpts().CPlusPlus20) @@ -93,7 +144,8 @@ void AvoidCArraysCheck::check(const MatchFinder::MatchResult &Result) { } else { RecommendTypes.push_back("'std::array'"); } - diag(ArrayType->getBeginLoc(), + + diag(ArrayTypeLoc.getBeginLoc(), "do not declare %select{C-style|C VLA}0 arrays, use %1 instead") << IsVLA << llvm::join(RecommendTypes, " or "); } diff --git a/clang-tools-extra/test/clang-tidy/checkers/modernize/avoid-c-arrays-ignores-strings.cpp b/clang-tools-extra/test/clang-tidy/checkers/modernize/avoid-c-arrays-ignores-strings.cpp index 906663828a547..18458bd47d347 100644 --- a/clang-tools-extra/test/clang-tidy/checkers/modernize/avoid-c-arrays-ignores-strings.cpp +++ b/clang-tools-extra/test/clang-tidy/checkers/modernize/avoid-c-arrays-ignores-strings.cpp @@ -7,3 +7,15 @@ const char array[] = {'n', 'a', 'm', 'e', '\0'}; void takeCharArray(const char name[]); // CHECK-MESSAGES: :[[@LINE-1]]:26: warning: do not declare C-style arrays, use 'std::array' or 'std::vector' instead [modernize-avoid-c-arrays] + +template <typename T = const char[10], typename U = char[10], char[10]> +// CHECK-MESSAGES: :[[@LINE-1]]:30: warning: do not declare C-style arrays, use 'std::array' instead [modernize-avoid-c-arrays] +// CHECK-MESSAGES: :[[@LINE-2]]:53: warning: do not declare C-style arrays, use 'std::array' instead [modernize-avoid-c-arrays] +// CHECK-MESSAGES: :[[@LINE-3]]:63: warning: do not declare C-style arrays, use 'std::array' instead [modernize-avoid-c-arrays] +void func() {} + +template <typename T = const char[], typename U = char[], char[]> +// CHECK-MESSAGES: :[[@LINE-1]]:30: warning: do not declare C-style arrays, use 'std::array' instead [modernize-avoid-c-arrays] +// CHECK-MESSAGES: :[[@LINE-2]]:51: warning: do not declare C-style arrays, use 'std::array' instead [modernize-avoid-c-arrays] +// CHECK-MESSAGES: :[[@LINE-3]]:59: warning: do not declare C-style arrays, use 'std::array' instead [modernize-avoid-c-arrays] +void fun() {} diff --git a/clang-tools-extra/test/clang-tidy/checkers/modernize/avoid-c-arrays.cpp b/clang-tools-extra/test/clang-tidy/checkers/modernize/avoid-c-arrays.cpp index 14eb2852c639a..0b474cc69db36 100644 --- a/clang-tools-extra/test/clang-tidy/checkers/modernize/avoid-c-arrays.cpp +++ b/clang-tools-extra/test/clang-tidy/checkers/modernize/avoid-c-arrays.cpp @@ -92,3 +92,162 @@ const char name[] = "Some string"; void takeCharArray(const char name[]); // CHECK-MESSAGES: :[[@LINE-1]]:26: warning: do not declare C-style arrays, use 'std::array' or 'std::vector' instead [modernize-avoid-c-arrays] + +namespace std { + template<class T, class U> + struct is_same { constexpr static bool value{false}; }; + + template<class T> + struct is_same<T, T> { constexpr static bool value{true}; }; + + template<class T, class U> + constexpr bool is_same_v = is_same<T, U>::value; + + template<class T> struct remove_const { typedef T type; }; + template<class T> struct remove_const<const T> { typedef T type; }; + + template<class T> + using remove_const_t = typename remove_const<T>::type; + + template<bool B, class T = void> struct enable_if {}; + template<class T> struct enable_if<true, T> { typedef T type; }; + + template< bool B, class T = void > + using enable_if_t = typename enable_if<B, T>::type; +} + +// below, no array type findings are expected within the template parameter declarations since no array type gets written explicitly +template <typename T, + bool = std::is_same_v<T, int>, + bool = std::is_same<T, int>::value, + bool = std::is_same_v<std::remove_const_t<T>, int>, + bool = std::is_same<std::remove_const_t<T>, int>::value, + bool = std::is_same_v<typename std::remove_const<T>::type, int>, + bool = std::is_same<typename std::remove_const<T>::type, int>::value, + std::enable_if_t<not(std::is_same_v<std::remove_const_t<T>, int>) && not(std::is_same_v<typename std::remove_const<T>::type, char>), bool> = true, + typename std::enable_if<not(std::is_same_v<std::remove_const_t<T>, int>) && not(std::is_same_v<typename std::remove_const<T>::type, char>), bool>::type = true, + typename = std::enable_if_t<not(std::is_same_v<std::remove_const_t<T>, int>) && not(std::is_same_v<typename std::remove_const<T>::type, char>)>, + typename = typename std::remove_const<T>::type, + typename = std::remove_const_t<T>> +class MyClassTemplate { + public: + // here, plenty of array type findings are expected for below template parameter declarations since array types get written explicitly + template <typename U = T, + bool = std::is_same_v<U, int[]>, + // CHECK-MESSAGES: :[[@LINE-1]]:38: warning: do not declare C-style arrays, use 'std::array' instead [modernize-avoid-c-arrays] + bool = std::is_same<U, int[10]>::value, + // CHECK-MESSAGES: :[[@LINE-1]]:36: warning: do not declare C-style arrays, use 'std::array' instead [modernize-avoid-c-arrays] + std::enable_if_t<not(std::is_same_v<std::remove_const_t<U>, int[]>) && not(std::is_same_v<typename std::remove_const<U>::type, char[10]>), bool> = true, + // CHECK-MESSAGES: :[[@LINE-1]]:73: warning: do not declare C-style arrays, use 'std::array' instead [modernize-avoid-c-arrays] + // CHECK-MESSAGES: :[[@LINE-2]]:140: warning: do not declare C-style arrays, use 'std::array' instead [modernize-avoid-c-arrays] + typename = typename std::remove_const<int[10]>::type, + // CHECK-MESSAGES: :[[@LINE-1]]:51: warning: do not declare C-style arrays, use 'std::array' instead [modernize-avoid-c-arrays] + typename = std::remove_const_t<int[]>> + // CHECK-MESSAGES: :[[@LINE-1]]:44: warning: do not declare C-style arrays, use 'std::array' instead [modernize-avoid-c-arrays] + class MyInnerClassTemplate { + public: + MyInnerClassTemplate(const U&) {} + private: + U field[3]; + // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: do not declare C-style arrays, use 'std::array' instead [modernize-avoid-c-arrays] + }; + + MyClassTemplate(const T&) {} + + private: + T field[7]; + // CHECK-MESSAGES: :[[@LINE-1]]:5: warning: do not declare C-style arrays, use 'std::array' instead [modernize-avoid-c-arrays] +}; + +// an explicit instantiation +template +class MyClassTemplate<int[2]>; +// CHECK-MESSAGES: :[[@LINE-1]]:23: warning: do not declare C-style arrays, use 'std::array' instead [modernize-avoid-c-arrays] + +using MyArrayType = int[3]; +// CHECK-MESSAGES: :[[@LINE-1]]:21: warning: do not declare C-style arrays, use 'std::array' instead [modernize-avoid-c-arrays] + +// another explicit instantiation +template +class MyClassTemplate<MyArrayType>; + +// below, no array type findings are expected within the template parameter declarations since no array type gets written explicitly +template <typename T, + bool = std::is_same_v<T, int>, + bool = std::is_same<T, int>::value, + bool = std::is_same_v<std::remove_const_t<T>, int>, + bool = std::is_same<std::remove_const_t<T>, int>::value, + bool = std::is_same_v<typename std::remove_const<T>::type, int>, + bool = std::is_same<typename std::remove_const<T>::type, int>::value, + std::enable_if_t<not(std::is_same_v<std::remove_const_t<T>, int>) && not(std::is_same_v<typename std::remove_const<T>::type, char>), bool> = true, + typename std::enable_if<not(std::is_same_v<std::remove_const_t<T>, int>) && not(std::is_same_v<typename std::remove_const<T>::type, char>), bool>::type = true, + typename = std::enable_if_t<not(std::is_same_v<std::remove_const_t<T>, int>) && not(std::is_same_v<typename std::remove_const<T>::type, char>)>, + typename = typename std::remove_const<T>::type, + typename = std::remove_const_t<T>> +void func(const T& param) { + int array1[1]; + // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: do not declare C-style arrays, use 'std::array' instead [modernize-avoid-c-arrays] + + T array2[2]; + // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: do not declare C-style arrays, use 'std::array' instead [modernize-avoid-c-arrays] + + T value; +} + +// here, plenty of array type findings are expected for below template parameter declarations since array types get written explicitly +template <typename T = int[], + // CHECK-MESSAGES: :[[@LINE-1]]:24: warning: do not declare C-style arrays, use 'std::array' instead [modernize-avoid-c-arrays] + bool = std::is_same_v<T, int[]>, + // CHECK-MESSAGES: :[[@LINE-1]]:36: warning: do not declare C-style arrays, use 'std::array' instead [modernize-avoid-c-arrays] + bool = std::is_same<T, int[10]>::value, + // CHECK-MESSAGES: :[[@LINE-1]]:34: warning: do not declare C-style arrays, use 'std::array' instead [modernize-avoid-c-arrays] + std::enable_if_t<not(std::is_same_v<std::remove_const_t<T>, int[]>) && not(std::is_same_v<typename std::remove_const<T>::type, char[10]>), bool> = true, + // CHECK-MESSAGES: :[[@LINE-1]]:71: warning: do not declare C-style arrays, use 'std::array' instead [modernize-avoid-c-arrays] + // CHECK-MESSAGES: :[[@LINE-2]]:138: warning: do not declare C-style arrays, use 'std::array' instead [modernize-avoid-c-arrays] + typename = typename std::remove_const<int[10]>::type, + // CHECK-MESSAGES: :[[@LINE-1]]:49: warning: do not declare C-style arrays, use 'std::array' instead [modernize-avoid-c-arrays] + typename = std::remove_const_t<int[]>> + // CHECK-MESSAGES: :[[@LINE-1]]:42: warning: do not declare C-style arrays, use 'std::array' instead [modernize-avoid-c-arrays] +void fun(const T& param) { + int array3[3]; + // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: do not declare C-style arrays, use 'std::array' instead [modernize-avoid-c-arrays] + + T array4[4]; + // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: do not declare C-style arrays, use 'std::array' instead [modernize-avoid-c-arrays] + + T value; +} + +template<typename T> +T some_constant{}; + +// explicit instantiation +template +int some_constant<int[5]>[5]; +// FIXME: why no diagnostics here? + +// explicit specialization +template<> +int some_constant<int[7]>[7]{}; +// CHECK-MESSAGES: :[[@LINE-1]]:1: warning: do not declare C-style arrays, use 'std::array' instead [modernize-avoid-c-arrays] +// CHECK-MESSAGES: :[[@LINE-2]]:19: warning: do not declare C-style arrays, use 'std::array' instead [modernize-avoid-c-arrays] + +void testArrayInTemplateType() { + int t[10]; + // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: do not declare C-style arrays, use 'std::array' instead [modernize-avoid-c-arrays] + + func(t); + fun(t); + + func<decltype(t)>({}); + fun<decltype(t)>({}); + + MyClassTemplate var1{t}; + MyClassTemplate<decltype(t)> var2{{}}; + + decltype(var1)::MyInnerClassTemplate var3{t}; + decltype(var1)::MyInnerClassTemplate<decltype(t)> var4{{}}; + + MyClassTemplate<decltype(t)>::MyInnerClassTemplate var5{t}; + MyClassTemplate<decltype(t)>::MyInnerClassTemplate<decltype(t)> var6{{}}; +} `````````` </details> https://github.com/llvm/llvm-project/pull/132924 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
