[clang-tidy] Abseil: no namepsace check

This check ensures that users of Abseil do not open namespace absl in their code, as that violates our compatibility guidelines.

AbseilMatcher.h written by Hugo Gonzalez.

Patch by Deanna Garcia!

llvm-svn: 340800

clang-tools-extra/clang-tidy/abseil/AbseilMatcher.h

@@ -0,0 +1,51 @@
+//===- AbseilMatcher.h - clang-tidy ---------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+
+namespace clang {
+namespace ast_matchers {
+
+/// Matches AST nodes that were found within Abseil files.
+///
+/// Example matches Y but not X
+///     (matcher = cxxRecordDecl(isInAbseilFile())
+/// \code
+///   #include "absl/strings/internal-file.h"
+///   class X {};
+/// \endcode
+/// absl/strings/internal-file.h:
+/// \code
+///   class Y {};
+/// \endcode
+///
+/// Usable as: Matcher<Decl>, Matcher<Stmt>, Matcher<TypeLoc>,
+/// Matcher<NestedNameSpecifierLoc>
+
+AST_POLYMORPHIC_MATCHER(isInAbseilFile,
+                        AST_POLYMORPHIC_SUPPORTED_TYPES(
+                            Decl, Stmt, TypeLoc, NestedNameSpecifierLoc)) {
+  auto &SourceManager = Finder->getASTContext().getSourceManager();
+  SourceLocation Loc = Node.getBeginLoc();
+  if (Loc.isInvalid())
+    return false;
+  const FileEntry *FileEntry =
+      SourceManager.getFileEntryForID(SourceManager.getFileID(Loc));
+  if (!FileEntry)
+    return false;
+  StringRef Filename = FileEntry->getName();
+  llvm::Regex RE(
+      "absl/(algorithm|base|container|debugging|memory|meta|numeric|strings|"
+      "synchronization|time|types|utility)");
+  return RE.match(Filename);
+}
+
+} // namespace ast_matchers
+} // namespace clang

clang-tools-extra/clang-tidy/abseil/AbseilTidyModule.cpp

@@ -12,6 +12,7 @@
 #include "../ClangTidyModuleRegistry.h"
 #include "DurationDivisionCheck.h"
 #include "FasterStrsplitDelimiterCheck.h"
+#include "NoNamespaceCheck.h"
 #include "StringFindStartswithCheck.h"
 
 namespace clang {
@@ -25,6 +26,7 @@ public:
         "abseil-duration-division");
     CheckFactories.registerCheck<FasterStrsplitDelimiterCheck>(
         "abseil-faster-strsplit-delimiter");
+    CheckFactories.registerCheck<NoNamespaceCheck>("abseil-no-namespace");
     CheckFactories.registerCheck<StringFindStartswithCheck>(
         "abseil-string-find-startswith");
   }

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

@@ -4,6 +4,7 @@ add_clang_library(clangTidyAbseilModule
   AbseilTidyModule.cpp
   DurationDivisionCheck.cpp
   FasterStrsplitDelimiterCheck.cpp
+  NoNamespaceCheck.cpp
   StringFindStartswithCheck.cpp
 
   LINK_LIBS

clang-tools-extra/clang-tidy/abseil/NoNamespaceCheck.cpp

@@ -0,0 +1,42 @@
+//===--- NoNamespaceCheck.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 "NoNamespaceCheck.h"
+#include "AbseilMatcher.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang {
+namespace tidy {
+namespace abseil {
+
+void NoNamespaceCheck::registerMatchers(MatchFinder *Finder) {
+  if (!getLangOpts().CPlusPlus)
+    return;
+
+  Finder->addMatcher(
+      namespaceDecl(hasName("::absl"), unless(isInAbseilFile()))
+          .bind("abslNamespace"),
+      this);
+}
+
+void NoNamespaceCheck::check(const MatchFinder::MatchResult &Result) {
+  const auto *abslNamespaceDecl =
+      Result.Nodes.getNodeAs<NamespaceDecl>("abslNamespace");
+
+  diag(abslNamespaceDecl->getLocation(),
+       "namespace 'absl' is reserved for implementation of the Abseil library "
+       "and should not be opened in user code");
+}
+
+} // namespace abseil
+} // namespace tidy
+} // namespace clang

clang-tools-extra/clang-tidy/abseil/NoNamespaceCheck.h

@@ -0,0 +1,36 @@
+//===--- NoNamespaceCheck.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_ABSEIL_NONAMESPACECHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_ABSEIL_NONAMESPACECHECK_H
+
+#include "../ClangTidy.h"
+
+namespace clang {
+namespace tidy {
+namespace abseil {
+
+/// This check ensures users don't open namespace absl, as that violates
+/// Abseil's compatibility guidelines.
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/abseil-no-namespace.html
+class NoNamespaceCheck : public ClangTidyCheck {
+public:
+  NoNamespaceCheck(StringRef Name, ClangTidyContext *Context)
+      : ClangTidyCheck(Name, Context) {}
+  void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+  void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+};
+
+} // namespace abseil
+} // namespace tidy
+} // namespace clang
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_ABSEIL_NONAMESPACECHECK_H

clang-tools-extra/docs/ReleaseNotes.rst

@@ -70,6 +70,12 @@ Improvements to clang-tidy
   Finds instances of ``absl::StrSplit()`` or ``absl::MaxSplits()`` where the
   delimiter is a single character string literal and replaces with a character.
 
+- New :doc:`abseil-no-namespace
+  <clang-tidy/checks/abseil-no-namespace>` check.
+
+  Ensures code does not open ``namespace absl`` as that violates Abseil's
+  compatibility guidelines.
+
 - New :doc:`readability-magic-numbers
   <clang-tidy/checks/readability-magic-numbers>` check.
 

clang-tools-extra/docs/clang-tidy/checks/abseil-no-namespace.rst

@@ -0,0 +1,21 @@
+.. title:: clang-tidy - abseil-no-namespace
+
+abseil-no-namespace
+===================
+
+Ensures code does not open ``namespace absl`` as that violates Abseil's
+compatibility guidelines. Code should not open ``namespace absl`` as that
+conflicts with Abseil's compatibility guidelines and may result in breakage.
+
+Any code that uses:
+
+.. code-block:: c++
+
+ namespace absl {
+  ...
+ }
+
+will be prompted with a warning.
+
+See `the full Abseil compatibility guidelines <https://
+abseil.io/about/compatibility>`_ for more information.

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

@@ -6,6 +6,7 @@ Clang-Tidy Checks
 .. toctree::
    abseil-duration-division
    abseil-faster-strsplit-delimiter
+   abseil-no-namespace
    abseil-string-find-startswith
    android-cloexec-accept
    android-cloexec-accept4

clang-tools-extra/test/clang-tidy/Inputs/absl/external-file.h

@@ -0,0 +1 @@
+namespace absl {}

clang-tools-extra/test/clang-tidy/Inputs/absl/strings/internal-file.h

@@ -0,0 +1 @@
+namespace absl {}

clang-tools-extra/test/clang-tidy/abseil-no-namespace.cpp

@@ -0,0 +1,24 @@
+// RUN: %check_clang_tidy %s abseil-no-namespace %t -- -- -I %S/Inputs
+// RUN: clang-tidy -checks='-*, abseil-no-namespace' -header-filter='.*' %s -- -I %S/Inputs 2>&1 | FileCheck %s
+
+/// Warning will not be triggered on internal Abseil code that is included.
+#include "absl/strings/internal-file.h"
+// CHECK-NOT: warning:
+
+/// Warning will be triggered on code that is not internal that is included.
+#include "absl/external-file.h"
+// CHECK: absl/external-file.h:1:11: warning: namespace 'absl' is reserved
+
+namespace absl {}
+// CHECK-MESSAGES: :[[@LINE-1]]:11: warning: namespace 'absl' is reserved for implementation of the Abseil library and should not be opened in user code [abseil-no-namespace]
+
+namespace absl {
+// CHECK-MESSAGES: :[[@LINE-1]]:11: warning: namespace 'absl'
+namespace std {
+int i = 5;
+}
+}
+
+// Things that shouldn't trigger the check
+int i = 5;
+namespace std {}