[clang-tidy] Add avoid-pragma-once.

clang-tools-extra/clang-tidy/portability/AvoidPragmaOnceCheck.cpp

@@ -0,0 +1,49 @@
+//===--- AvoidPragmaOnceCheck.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 "AvoidPragmaOnceCheck.h"
+
+#include "clang/Basic/SourceManager.h"
+#include "clang/Lex/PPCallbacks.h"
+#include "clang/Lex/Preprocessor.h"
+#include "llvm/ADT/StringRef.h"
+
+namespace clang::tidy::portability {
+
+class PragmaOnceCallbacks : public PPCallbacks {
+public:
+  PragmaOnceCallbacks(AvoidPragmaOnceCheck *Check, const SourceManager &SM)
+      : Check(Check), SM(SM) {}
+  void PragmaDirective(SourceLocation Loc,
+                       PragmaIntroducerKind Introducer) override {
+    auto Str = llvm::StringRef(SM.getCharacterData(Loc));
+    if (!Str.consume_front("#")) {
+      return;
+    }
+    Str = Str.trim();
+    if (!Str.consume_front("pragma")) {
+      return;
+    }
+    Str = Str.trim();
+    if (Str.starts_with("once")) {
+      Check->diag(Loc, "Avoid pragma once.");
+    }
+  }
+
+private:
+  AvoidPragmaOnceCheck *Check;
+  const SourceManager &SM;
+};
+
+void AvoidPragmaOnceCheck::registerPPCallbacks(const SourceManager &SM,
+                                               Preprocessor *PP,
+                                               Preprocessor *ModuleExpanderPP) {
+  PP->addPPCallbacks(std::make_unique<PragmaOnceCallbacks>(this, SM));
+}
+
+} // namespace clang::tidy::portability

clang-tools-extra/clang-tidy/portability/AvoidPragmaOnceCheck.h

@@ -0,0 +1,34 @@
+//===--- AvoidPragmaOnceCheck.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_PORTABILITY_AVOIDPRAGMAONCECHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_PORTABILITY_AVOIDPRAGMAONCECHECK_H
+
+#include "../ClangTidyCheck.h"
+
+namespace clang::tidy::portability {
+
+/// FIXME: Write a short description.
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/portability/avoid-pragma-once.html
+class AvoidPragmaOnceCheck : public ClangTidyCheck {
+public:
+  AvoidPragmaOnceCheck(StringRef Name, ClangTidyContext *Context)
+      : ClangTidyCheck(Name, Context) {}
+  bool isLanguageVersionSupported(const LangOptions &LangOpts) const override {
+    return LangOpts.CPlusPlus;
+  }
+
+  void registerPPCallbacks(const SourceManager &SM, Preprocessor *PP,
+                           Preprocessor *ModuleExpanderPP) override;
+};
+
+} // namespace clang::tidy::portability
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_PORTABILITY_AVOIDPRAGMAONCECHECK_H

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

@@ -5,6 +5,7 @@ set(LLVM_LINK_COMPONENTS
   )
 
 add_clang_library(clangTidyPortabilityModule STATIC
+  AvoidPragmaOnceCheck.cpp
   PortabilityTidyModule.cpp
   RestrictSystemIncludesCheck.cpp
   SIMDIntrinsicsCheck.cpp

clang-tools-extra/clang-tidy/portability/PortabilityTidyModule.cpp

@@ -9,6 +9,7 @@
 #include "../ClangTidy.h"
 #include "../ClangTidyModule.h"
 #include "../ClangTidyModuleRegistry.h"
+#include "AvoidPragmaOnceCheck.h"
 #include "RestrictSystemIncludesCheck.h"
 #include "SIMDIntrinsicsCheck.h"
 #include "StdAllocatorConstCheck.h"
@@ -20,6 +21,8 @@ namespace portability {
 class PortabilityModule : public ClangTidyModule {
 public:
   void addCheckFactories(ClangTidyCheckFactories &CheckFactories) override {
+    CheckFactories.registerCheck<AvoidPragmaOnceCheck>(
+        "portability-avoid-pragma-once");
     CheckFactories.registerCheck<RestrictSystemIncludesCheck>(
         "portability-restrict-system-includes");
     CheckFactories.registerCheck<SIMDIntrinsicsCheck>(

clang-tools-extra/docs/ReleaseNotes.rst

@@ -142,6 +142,11 @@ New checks
   Finds potentially erroneous calls to ``reset`` method on smart pointers when
   the pointee type also has a ``reset`` method.
 
+- New :doc:`portability-avoid-pragma-once
+  <clang-tidy/checks/portability/avoid-pragma-once>` check.
+
+  A check that catches pragma once.
+
 New check aliases
 ^^^^^^^^^^^^^^^^^
 

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

@@ -351,6 +351,7 @@ Clang-Tidy Checks
    :doc:`performance-type-promotion-in-math-fn <performance/type-promotion-in-math-fn>`, "Yes"
    :doc:`performance-unnecessary-copy-initialization <performance/unnecessary-copy-initialization>`, "Yes"
    :doc:`performance-unnecessary-value-param <performance/unnecessary-value-param>`, "Yes"
+   :doc:`portability-avoid-pragma-once <portability/avoid-pragma-once>`, "Yes"
    :doc:`portability-restrict-system-includes <portability/restrict-system-includes>`, "Yes"
    :doc:`portability-simd-intrinsics <portability/simd-intrinsics>`,
    :doc:`portability-std-allocator-const <portability/std-allocator-const>`,

clang-tools-extra/docs/clang-tidy/checks/portability/avoid-pragma-once.rst

@@ -0,0 +1,12 @@
+.. title:: clang-tidy - portability-avoid-pragma-once
+
+portability-avoid-pragma-once
+=============================
+
+This check catches pragma once usage.
+
+For example:
+
+```
+#pragma once // Bad: Avoid pragma once.
+```

clang-tools-extra/test/clang-tidy/checkers/portability/Inputs/avoid-pragma-once/lib.h

@@ -0,0 +1 @@
+#pragma once

clang-tools-extra/test/clang-tidy/checkers/portability/avoid-pragma-once.cpp

@@ -0,0 +1,5 @@
+// RUN: %check_clang_tidy %s portability-avoid-pragma-once %t \
+// RUN:   -- --header-filter='.*' --  -I%S/Inputs/avoid-pragma-once
+
+#include "lib.h"
+// CHECK-MESSAGES: lib.h:1:1: warning: Avoid pragma once.