reformat

Author: HerrCai0907

clang-tools-extra/clang-tidy/readability/CMakeLists.txt

@@ -23,6 +23,7 @@ add_clang_library(clangTidyReadabilityModule
   IdentifierLengthCheck.cpp
   IdentifierNamingCheck.cpp
   ImplicitBoolConversionCheck.cpp
+  UnnecessaryExternalLinkageCheck.cpp
   RedundantInlineSpecifierCheck.cpp
   InconsistentDeclarationParameterNameCheck.cpp
   IsolateDeclarationCheck.cpp

clang-tools-extra/clang-tidy/readability/ReadabilityTidyModule.cpp

@@ -58,6 +58,7 @@
 #include "StringCompareCheck.h"
 #include "SuspiciousCallArgumentCheck.h"
 #include "UniqueptrDeleteReleaseCheck.h"
+#include "UnnecessaryExternalLinkageCheck.h"
 #include "UppercaseLiteralSuffixCheck.h"
 #include "UseAnyOfAllOfCheck.h"
 #include "UseStdMinMaxCheck.h"
@@ -106,6 +107,8 @@ class ReadabilityModule : public ClangTidyModule {
         "readability-identifier-naming");
     CheckFactories.registerCheck<ImplicitBoolConversionCheck>(
         "readability-implicit-bool-conversion");
+    CheckFactories.registerCheck<UnnecessaryExternalLinkageCheck>(
+        "readability-unnecessary-external-linkage");
     CheckFactories.registerCheck<MathMissingParenthesesCheck>(
         "readability-math-missing-parentheses");
     CheckFactories.registerCheck<RedundantInlineSpecifierCheck>(

clang-tools-extra/clang-tidy/readability/UnnecessaryExternalLinkageCheck.cpp

@@ -0,0 +1,82 @@
+//===--- UnnecessaryExternalLinkageCheck.cpp - clang-tidy
+//---------------------------------===//
+//
+// 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 "UnnecessaryExternalLinkageCheck.h"
+#include "clang/AST/Decl.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/ASTMatchers/ASTMatchers.h"
+#include "clang/ASTMatchers/ASTMatchersMacros.h"
+#include "clang/Basic/Specifiers.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::readability {
+
+namespace {
+
+AST_POLYMORPHIC_MATCHER(isFirstDecl,
+                        AST_POLYMORPHIC_SUPPORTED_TYPES(FunctionDecl,
+                                                        VarDecl)) {
+  return Node.isFirstDecl();
+}
+
+AST_MATCHER(Decl, isInMainFile) {
+  for (const Decl *D : Node.redecls())
+    if (!Finder->getASTContext().getSourceManager().isInMainFile(
+            D->getLocation()))
+      return false;
+  return true;
+}
+
+AST_POLYMORPHIC_MATCHER(isExternStorageClass,
+                        AST_POLYMORPHIC_SUPPORTED_TYPES(FunctionDecl,
+                                                        VarDecl)) {
+  return Node.getStorageClass() == SC_Extern;
+}
+
+} // namespace
+
+void UnnecessaryExternalLinkageCheck::registerMatchers(MatchFinder *Finder) {
+  auto Common = allOf(isFirstDecl(), isInMainFile(),
+                      unless(anyOf(
+                          // 1. internal linkage
+                          isStaticStorageClass(), isInAnonymousNamespace(),
+                          // 2. explicit external linkage
+                          isExternStorageClass(), isExternC(),
+                          // 3. template
+                          isExplicitTemplateSpecialization(),
+                          clang::ast_matchers::isTemplateInstantiation(),
+                          // 4. friend
+                          hasAncestor(friendDecl()))));
+  Finder->addMatcher(
+      functionDecl(Common, unless(cxxMethodDecl()), unless(isMain()))
+          .bind("fn"),
+      this);
+  Finder->addMatcher(varDecl(Common, hasGlobalStorage()).bind("var"), this);
+}
+
+static constexpr StringRef Message =
+    "%0 %1 can be internal linkage, "
+    "marking as static or using anonymous namespace can avoid external "
+    "linkage.";
+
+void UnnecessaryExternalLinkageCheck::check(
+    const MatchFinder::MatchResult &Result) {
+  if (const auto *FD = Result.Nodes.getNodeAs<FunctionDecl>("fn")) {
+    diag(FD->getLocation(), Message) << "function" << FD;
+    return;
+  }
+  if (const auto *VD = Result.Nodes.getNodeAs<VarDecl>("var")) {
+    diag(VD->getLocation(), Message) << "variable" << VD;
+    return;
+  }
+  llvm_unreachable("");
+}
+
+} // namespace clang::tidy::readability

clang-tools-extra/clang-tidy/readability/UnnecessaryExternalLinkageCheck.h

@@ -0,0 +1,33 @@
+//===--- UnnecessaryExternalLinkageCheck.h - clang-tidy ---------*- C++ -*-===//
+//
+// 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_UNNECESSARYEXTERNALLINKAGECHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_UNNECESSARYEXTERNALLINKAGECHECK_H
+
+#include "../ClangTidyCheck.h"
+
+namespace clang::tidy::readability {
+
+/// Detects variable and function can be marked as static.
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/readability/unnecessary-external-linkage.html
+class UnnecessaryExternalLinkageCheck : public ClangTidyCheck {
+public:
+  UnnecessaryExternalLinkageCheck(StringRef Name, ClangTidyContext *Context)
+      : ClangTidyCheck(Name, Context) {}
+  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_UNNECESSARYEXTERNALLINKAGECHECK_H

clang-tools-extra/docs/ReleaseNotes.rst

@@ -151,6 +151,11 @@ New checks
   Enforces consistent style for enumerators' initialization, covering three
   styles: none, first only, or all initialized explicitly.
 
+- New :doc:`readability-unnecessary-external-linkage
+  <clang-tidy/checks/readability/unnecessary-external-linkage>` check.
+
+  Detects variable and function can be marked as static.
+
 - New :doc:`readability-math-missing-parentheses
   <clang-tidy/checks/readability/math-missing-parentheses>` check.
 

clang-tools-extra/docs/clang-tidy/checks/list.rst

@@ -390,6 +390,7 @@ Clang-Tidy Checks
    :doc:`readability-string-compare <readability/string-compare>`, "Yes"
    :doc:`readability-suspicious-call-argument <readability/suspicious-call-argument>`,
    :doc:`readability-uniqueptr-delete-release <readability/uniqueptr-delete-release>`, "Yes"
+   :doc:`readability-unnecessary-external-linkage <readability/unnecessary-external-linkage>`,
    :doc:`readability-uppercase-literal-suffix <readability/uppercase-literal-suffix>`, "Yes"
    :doc:`readability-use-anyofallof <readability/use-anyofallof>`,
    :doc:`readability-use-std-min-max <readability/use-std-min-max>`, "Yes"

clang-tools-extra/docs/clang-tidy/checks/readability/unnecessary-external-linkage.rst

@@ -0,0 +1,26 @@
+.. title:: clang-tidy - readability-unnecessary-external-linkage
+
+readability-unnecessary-external-linkage
+========================================
+
+Detects variable and function can be marked as static.
+
+Static functions and variables are scoped to a single file. Marking functions
+and variables as static helps to better remove dead code. In addition, it gives
+the compiler more information and can help compiler make more aggressive
+optimizations.
+
+Example:
+
+.. code-block:: c++
+  int v1; // can be marked as static
+
+  void fn1(); // can be marked as static
+
+  namespace {
+    // already in anonymous namespace
+    int v2;
+    void fn2();
+  }
+  // already declared as extern
+  extern int v2;

clang-tools-extra/test/clang-tidy/checkers/readability/Inputs/mark-static-var/func.h

@@ -0,0 +1,3 @@
+#pragma once
+
+void func_header();

clang-tools-extra/test/clang-tidy/checkers/readability/Inputs/mark-static-var/var.h

@@ -0,0 +1,3 @@
+#pragma once
+
+extern int gloabl_header;

clang-tools-extra/test/clang-tidy/checkers/readability/unnecessary-external-linkage-func.cpp

@@ -0,0 +1,30 @@
+// RUN: %check_clang_tidy %s readability-unnecessary-external-linkage %t -- -- -I%S/Inputs/mark-static-var
+
+#include "func.h"
+
+void func() {}
+// CHECK-MESSAGES: :[[@LINE-1]]:6: warning: function 'func'
+
+template<class T>
+void func_template() {}
+// CHECK-MESSAGES: :[[@LINE-1]]:6: warning: function 'func_template'
+
+struct S {
+  void method();
+};
+void S::method() {}
+
+void func_header();
+extern void func_extern();
+static void func_static();
+namespace {
+void func_anonymous_ns();
+} // namespace
+
+int main(int argc, const char*argv[]) {}
+
+extern "C" {
+void func_extern_c_1() {}
+}
+
+extern "C" void func_extern_c_2() {}

clang-tools-extra/test/clang-tidy/checkers/readability/unnecessary-external-linkage-var.cpp

@@ -0,0 +1,40 @@
+// RUN: %check_clang_tidy %s readability-unnecessary-external-linkage %t -- -- -I%S/Inputs/mark-static-var
+
+#include "var.h"
+
+int global;
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: variable 'global'
+
+template<class T>
+T global_template;
+// CHECK-MESSAGES: :[[@LINE-1]]:3: warning: variable 'global_template'
+
+int gloabl_header;
+
+extern int global_extern;
+
+static int global_static;
+
+namespace {
+static int global_anonymous_ns;
+namespace NS {
+static int global_anonymous_ns;
+}
+}
+
+static void f(int para) {
+  int local;
+  static int local_static;
+}
+
+struct S {
+  int m1;
+  static int m2;
+};
+int S::m2;
+
+extern "C" {
+int global_in_extern_c_1;
+}
+
+extern "C" int global_in_extern_c_2;