use std::array<> or std::vector<>

HerrCai0907 · HerrCai0907 · commit f7399cf0cf0a · 2024-09-14T17:27:21.000+08:00
diff --git a/clang-tools-extra/clang-tidy/modernize/AvoidCArraysCheck.cpp b/clang-tools-extra/clang-tidy/modernize/AvoidCArraysCheck.cpp
@@ -39,13 +39,6 @@ AST_MATCHER(clang::ParmVarDecl, isArgvOfMain) {
   return FD ? FD->isMain() : false;
 }
 
-AST_MATCHER_P(clang::TypeLoc, alwaysTrue,
-              clang::ast_matchers::internal::Matcher<clang::TypeLoc>,
-              InnerMatcher) {
-  InnerMatcher.matches(Node, Finder, Builder);
-  return true;
-}
-
 } // namespace
 
 AvoidCArraysCheck::AvoidCArraysCheck(StringRef Name, ClangTidyContext *Context)
@@ -68,7 +61,7 @@ void AvoidCArraysCheck::registerMatchers(MatchFinder *Finder) {
 
   Finder->addMatcher(
       typeLoc(hasValidBeginLoc(), hasType(arrayType()),
-              alwaysTrue(hasParent(parmVarDecl().bind("param_decl"))),
+              optionally(hasParent(parmVarDecl().bind("param_decl"))),
               unless(anyOf(hasParent(parmVarDecl(isArgvOfMain())),
                            hasParent(varDecl(isExternC())),
                            hasParent(fieldDecl(
@@ -85,20 +78,25 @@ void AvoidCArraysCheck::check(const MatchFinder::MatchResult &Result) {
       Result.Nodes.getNodeAs<ParmVarDecl>("param_decl") != nullptr;
   const bool IsVLA = ArrayType->getTypePtr()->isVariableArrayType();
   enum class RecommendType { Array, Vector, Span };
-  RecommendType RecommendType = RecommendType::Array;
+  llvm::SmallVector<const char *> RecommendTypes{};
   if (IsVLA) {
-    RecommendType = RecommendType::Vector;
+    RecommendTypes.push_back("std::vector<>");
   } else if (ArrayType->getTypePtr()->isIncompleteArrayType() && IsInParam) {
     // in function parameter, we also don't know the size of
     // IncompleteArrayType.
-    RecommendType = Result.Context->getLangOpts().CPlusPlus20
-                        ? RecommendType::Span
-                        : RecommendType::Vector;
+    if (Result.Context->getLangOpts().CPlusPlus20)
+      RecommendTypes.push_back("std::span<>");
+    else {
+      RecommendTypes.push_back("std::array<>");
+      RecommendTypes.push_back("std::vector<>");
+    }
+  } else {
+    RecommendTypes.push_back("std::array<>");
   }
+  llvm::errs() << llvm::join(RecommendTypes, " or ") << "\n";
   diag(ArrayType->getBeginLoc(),
-       "do not declare %select{C-style|C VLA}0 arrays, use "
-       "%select{std::array<>|std::vector<>|std::span<>}1 instead")
-      << IsVLA << static_cast<int>(RecommendType);
+       "do not declare %select{C-style|C VLA}0 arrays, use %1 instead")
+      << IsVLA << llvm::join(RecommendTypes, " or ");
 }
 
 } // namespace clang::tidy::modernize
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -112,8 +112,9 @@ Changes in existing checks
   the offending code with ``reinterpret_cast``, to more clearly express intent.
 
 - Improved :doc:`modernize-avoid-c-arrays
-  <clang-tidy/checks/modernize/avoid-c-arrays>` check to suggest use std::span
-  as replacement of c array in C++20.
+  <clang-tidy/checks/modernize/avoid-c-arrays>` check to suggest using 
+  ``std::span`` as replacement of incomplete C array in C++20 and ``std::vector`` 
+  in the versions before C++20.
 
 - Improved :doc:`modernize-use-std-format
   <clang-tidy/checks/modernize/use-std-format>` check to support replacing
diff --git a/clang-tools-extra/docs/clang-tidy/checks/modernize/avoid-c-arrays.rst b/clang-tools-extra/docs/clang-tidy/checks/modernize/avoid-c-arrays.rst
@@ -10,6 +10,9 @@ modernize-avoid-c-arrays
 Finds C-style array types and recommend to use ``std::array<>`` /
 ``std::vector<>``. All types of C arrays are diagnosed.
 
+For incomplete C-style array types appeared in parameters, It would be better to
+use ``std::span`` / ``gsl::span`` as replacement.
+
 However, fix-it are potentially dangerous in header files and are therefore not
 emitted right now.
 
diff --git a/clang-tools-extra/test/clang-tidy/checkers/modernize/avoid-c-arrays-ignores-main.cpp b/clang-tools-extra/test/clang-tidy/checkers/modernize/avoid-c-arrays-ignores-main.cpp
@@ -1,7 +1,7 @@
 // RUN: %check_clang_tidy -std=c++17 %s modernize-avoid-c-arrays %t
 
 int not_main(int argc, char *argv[]) {
-  // CHECK-MESSAGES: :[[@LINE-1]]:24: warning: do not declare C-style arrays, use std::vector<> instead
+  // CHECK-MESSAGES: :[[@LINE-1]]:24: warning: do not declare C-style arrays, use std::array<> or std::vector<> instead
   int f4[] = {1, 2};
   // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: do not declare C-style arrays, use std::array<> instead
 }
@@ -11,7 +11,7 @@ int main(int argc, char *argv[]) {
   // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: do not declare C-style arrays, use std::array<> instead
 
   auto not_main = [](int argc, char *argv[]) {
-    // CHECK-MESSAGES: :[[@LINE-1]]:32: warning: do not declare C-style arrays, use std::vector<> instead
+    // CHECK-MESSAGES: :[[@LINE-1]]:32: warning: do not declare C-style arrays, use std::array<> or std::vector<> instead
     int f6[] = {1, 2};
     // CHECK-MESSAGES: :[[@LINE-1]]:5: warning: do not declare C-style arrays, use std::array<> instead
   };
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
@@ -6,4 +6,4 @@ const char array[] = {'n', 'a', 'm', 'e', '\0'};
 // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: do not declare C-style arrays, use std::array<> instead [modernize-avoid-c-arrays]
 
 void takeCharArray(const char name[]);
-// CHECK-MESSAGES: :[[@LINE-1]]:26: warning: do not declare C-style arrays, use std::vector<> instead [modernize-avoid-c-arrays]
+// CHECK-MESSAGES: :[[@LINE-1]]:26: warning: do not declare C-style arrays, use std::array<> or std::vector<> instead [modernize-avoid-c-arrays]
diff --git a/clang-tools-extra/test/clang-tidy/checkers/modernize/avoid-c-arrays-ignores-three-arg-main.cpp b/clang-tools-extra/test/clang-tidy/checkers/modernize/avoid-c-arrays-ignores-three-arg-main.cpp
@@ -1,8 +1,8 @@
 // RUN: %check_clang_tidy -std=c++17 %s modernize-avoid-c-arrays %t
 
 int not_main(int argc, char *argv[], char *argw[]) {
-  // CHECK-MESSAGES: :[[@LINE-1]]:24: warning: do not declare C-style arrays, use std::vector<> instead
-  // CHECK-MESSAGES: :[[@LINE-2]]:38: warning: do not declare C-style arrays, use std::vector<> instead
+  // CHECK-MESSAGES: :[[@LINE-1]]:24: warning: do not declare C-style arrays, use std::array<> or std::vector<> instead
+  // CHECK-MESSAGES: :[[@LINE-2]]:38: warning: do not declare C-style arrays, use std::array<> or std::vector<> instead
   int f4[] = {1, 2};
   // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: do not declare C-style arrays, use std::array<> instead
 }
@@ -12,8 +12,8 @@ int main(int argc, char *argv[], char *argw[]) {
   // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: do not declare C-style arrays, use std::array<> instead
 
   auto not_main = [](int argc, char *argv[], char *argw[]) {
-    // CHECK-MESSAGES: :[[@LINE-1]]:32: warning: do not declare C-style arrays, use std::vector<> instead
-    // CHECK-MESSAGES: :[[@LINE-2]]:46: warning: do not declare C-style arrays, use std::vector<> instead
+    // CHECK-MESSAGES: :[[@LINE-1]]:32: warning: do not declare C-style arrays, use std::array<> or std::vector<> instead
+    // CHECK-MESSAGES: :[[@LINE-2]]:46: warning: do not declare C-style arrays, use std::array<> or std::vector<> instead
     int f6[] = {1, 2};
     // CHECK-MESSAGES: :[[@LINE-1]]:5: warning: do not declare C-style arrays, use std::array<> instead
   };
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
@@ -91,4 +91,4 @@ const char name[] = "Some string";
 // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: do not declare C-style arrays, use std::array<> instead [modernize-avoid-c-arrays]
 
 void takeCharArray(const char name[]);
-// CHECK-MESSAGES: :[[@LINE-1]]:26: warning: do not declare C-style arrays, use std::vector<> instead [modernize-avoid-c-arrays]
+// CHECK-MESSAGES: :[[@LINE-1]]:26: warning: do not declare C-style arrays, use std::array<> or std::vector<> instead [modernize-avoid-c-arrays]
