[clang-tidy ObjC] [1/3] New module `objc` for Objective-C checks

[benhamilton]

Summary

This is part 1 of 3 of a series of changes to improve Objective-C
linting in clang-tidy.

This introduces a new clang-tidy module, objc, specifically for
Objective-C / Objective-C++ checks.

The module is currently empty; D39142 adds the first check.

Test Plan: ninja check-clang-tools

[benhamilton]

• Add missing link lines for clang-tidy/tool and clang-tidy/plugin

[benhamilton]

• Ensure plugin and tool actually link ObjCModule by referencing symbol

[hokein]

Looks good from my side. I'd like to see whether @alexfh has further comments on it.

clang-tidy/objc/CMakeLists.txt

13

Is this dependency needed?

unittests/clang-tidy/ObjCModuleTest.cpp

2

We need the license statement for this file, I think.

[benhamilton]

• @hokein: Add copyright, remove unneeded dep

[benhamilton]

clang-tidy/objc/CMakeLists.txt

13

Whoops, no. Copy-paste error.

unittests/clang-tidy/ObjCModuleTest.cpp

2

I started with GoogleModuleTest.cpp, which is also missing the license statement. Added here.

clang-tidy/CMakeLists.txt

 add_subdirectory(cert)
 add_subdirectory(cppcoreguidelines)
 add_subdirectory(google)
 add_subdirectory(hicpp)
 add_subdirectory(llvm)
 add_subdirectory(misc)
 add_subdirectory(modernize)
 add_subdirectory(mpi)
+add_subdirectory(objc)
 add_subdirectory(performance)
 add_subdirectory(plugin)
 add_subdirectory(readability)
 add_subdirectory(tool)
 add_subdirectory(utils)

clang-tidy/objc/CMakeLists.txt

+set(LLVM_LINK_COMPONENTS support)
+
+add_clang_library(clangTidyObjCModule
+  ObjCTidyModule.cpp
+
+  LINK_LIBS
+  clangAST
+  clangASTMatchers
+  clangBasic
+  clangLex
+  clangTidy
+  clangTidyReadabilityModule
+  clangTidyUtils
+  )

clang-tidy/objc/ObjCTidyModule.cpp

+//===--- ObjCTidyModule.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 "../ClangTidy.h"
+#include "../ClangTidyModule.h"
+#include "../ClangTidyModuleRegistry.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang {
+namespace tidy {
+namespace objc {
+
+class ObjCModule : public ClangTidyModule {
+public:
+  void addCheckFactories(ClangTidyCheckFactories &CheckFactories) override {
+    // TODO(D39142): Add checks here.
+  }
+};
+
+// Register the ObjCTidyModule using this statically initialized variable.
+static ClangTidyModuleRegistry::Add<ObjCModule> X(
+    "objc-module",
+    "Adds Objective-C lint checks.");
+
+} // namespace objc
+
+// This anchor is used to force the linker to link in the generated object file
+// and thus register the ObjCModule.
+volatile int ObjCModuleAnchorSource = 0;
+
+} // namespace tidy
+} // namespace clang

clang-tidy/plugin/CMakeLists.txt

add_clang_library(clangTidyPlugin
   clangTidyBoostModule
   clangTidyCERTModule
   clangTidyCppCoreGuidelinesModule
   clangTidyGoogleModule
   clangTidyLLVMModule
   clangTidyMiscModule
   clangTidyModernizeModule
   clangTidyMPIModule
+  clangTidyObjCModule
   clangTidyPerformanceModule
   clangTidyReadabilityModule
   clangTooling
   )

clang-tidy/tool/CMakeLists.txt

target_link_libraries(clang-tidy
   clangTidyCERTModule
   clangTidyCppCoreGuidelinesModule
   clangTidyGoogleModule
   clangTidyHICPPModule
   clangTidyLLVMModule
   clangTidyMiscModule
   clangTidyModernizeModule
   clangTidyMPIModule
+  clangTidyObjCModule
   clangTidyPerformanceModule
   clangTidyReadabilityModule
   clangTooling
   clangToolingCore
   )
 
 install(TARGETS clang-tidy
   RUNTIME DESTINATION bin)
 
 install(PROGRAMS clang-tidy-diff.py DESTINATION share/clang)
 install(PROGRAMS run-clang-tidy.py DESTINATION share/clang)

docs/ReleaseNotes.rst

 Improvements to clang-rename
 ----------------------------
 
 The improvements are...
 
 Improvements to clang-tidy
 --------------------------
 
+- New module `objc` for Objective-C style checks.
+
 - Renamed checks to use correct term "implicit conversion" instead of "implicit
   cast" and modified messages and option names accordingly:
 
     * **performance-implicit-cast-in-loop** was renamed to
       `performance-implicit-conversion-in-loop
       <http://clang.llvm.org/extra/clang-tidy/checks/performance-implicit-conversion-in-loop.html>`_
     * **readability-implicit-bool-cast** was renamed to
       `readability-implicit-bool-conversion

docs/clang-tidy/index.rst

 ``clang-analyzer-``    Clang Static Analyzer checks.
 ``google-``            Checks related to Google coding conventions.
 ``hicpp-``             Checks related to High Integrity C++ Coding Standard.
 ``llvm-``              Checks related to the LLVM coding conventions.
 ``misc-``              Checks that we didn't have a better category for.
 ``modernize-``         Checks that advocate usage of modern (currently "modern"
                        means "C++11") language constructs.
 ``mpi-``               Checks related to MPI (Message Passing Interface).
+``objc-``              Checks related to Objective-C coding conventions.
 ``performance-``       Checks that target performance-related issues.
 ``readability-``       Checks that target readability-related issues that don't
                        relate to any particular coding style.
 ====================== =========================================================
 
 Clang diagnostics are treated in a similar way as check diagnostics. Clang
 diagnostics are displayed by :program:`clang-tidy` and can be filtered out using
 ``-checks=`` option. However, the ``-checks=`` option does not affect
|-+
     |-- GoogleTidyModule.cpp
     |-- GoogleTidyModule.h
           ...
   |-- llvm/                         # LLVM clang-tidy module.
   |-+
     |-- LLVMTidyModule.cpp
     |-- LLVMTidyModule.h
           ...
+  |-- objc/                         # Objective-C clang-tidy module.
+  |-+
+    |-- ObjCTidyModule.cpp
+    |-- ObjCTidyModule.h
+          ...
   |-- tool/                         # Sources of the clang-tidy binary.
           ...
   test/clang-tidy/                  # Integration tests.
       ...
   unittests/clang-tidy/             # Unit tests.
   |-- ClangTidyTest.h
   |-- GoogleModuleTest.cpp
   |-- LLVMModuleTest.cpp
+  |-- ObjCModuleTest.cpp
       ...
 
 
 Writing a clang-tidy Check
 --------------------------
 
 So you have an idea of a useful check for :program:`clang-tidy`.
 

unittests/clang-tidy/CMakeLists.txt

 set(LLVM_LINK_COMPONENTS
   support
   )
 
 get_filename_component(CLANG_LINT_SOURCE_DIR
   ${CMAKE_CURRENT_SOURCE_DIR}/../../clang-tidy REALPATH)
 include_directories(${CLANG_LINT_SOURCE_DIR})
 
 add_extra_unittest(ClangTidyTests
   ClangTidyDiagnosticConsumerTest.cpp
   ClangTidyOptionsTest.cpp
   IncludeInserterTest.cpp
   GoogleModuleTest.cpp
   LLVMModuleTest.cpp
   MiscModuleTest.cpp
   NamespaceAliaserTest.cpp
+  ObjCModuleTest.cpp
   OverlappingReplacementsTest.cpp
   UsingInserterTest.cpp
   ReadabilityModuleTest.cpp)
 
 target_link_libraries(ClangTidyTests
   clangAST
   clangASTMatchers
   clangBasic
   clangFrontend
   clangLex
   clangTidy
   clangTidyAndroidModule
   clangTidyGoogleModule
   clangTidyLLVMModule
   clangTidyMiscModule
+  clangTidyObjCModule
   clangTidyReadabilityModule
   clangTidyUtils
   clangTooling
   clangToolingCore
   )

unittests/clang-tidy/ObjCModuleTest.cpp

+#include "ClangTidyTest.h"
+#include "gtest/gtest.h"
+
+namespace clang {
+namespace tidy {
+namespace test {
+
+// TODO(D39142) Add unit tests for the ObjC module here once a check lands.
+
+} // namespace test
+} // namespace tidy
+} // namespace clang