[clang-tidy] Share the forced linking code between clang-tidy tool and plugin

[yvvan]

Summary

Extract code that forces linking to the separate header and include it in both plugin and standalone tool

[lebedev.ri]

1. Please always upload all patches with full context.
2. There are two places where this pattern exists - this file, and tool/ClangTidyMain.cpp. It clearly leads to such issues, Can this be reworked to be just one file that is simply included in both places?

[yvvan]

In D55595#1328100, @lebedev.ri wrote:

1. Please always upload all patches with full context.
2. There are two places where this pattern exists - this file, and tool/ClangTidyMain.cpp. It clearly leads to such issues, Can this be reworked to be just one file that is simply included in both places?

1. Usually I do that but this time used tortoisesvn to generate the patch...
2. Makes sense.

[lebedev.ri]

clang-tidy/ClangTidyForceLinker.h

1

Standard prologue missing

[yvvan]

Add standard prologue to the new header

[lebedev.ri]

Thanks, LG.
You probably may want to wait a bit (a day?) in case others want to comment.

[steveire]

FYI, CMake target property INTERFACE_SOURCES is designed to make this easy.

For each module you would generate a file containing

extern volatile int ${MODULE_NAME}ModuleAnchorSource;
static int LLVM_ATTRIBUTE_UNUSED ${MODULE_NAME}ModuleAnchorDestination =
    ${MODULE_NAME}ModuleAnchorSource;

and then put that generated file in the INTERFACE_SOURCES of each module.

target_sources(${MODULE_NAME} INTERFACE ${THE_GENERATED_FILE}.cpp)

Then, you don't need to maintain it in C++ like this. It is DRY because the target_link_libraries entry for the library is what causes the symbol to be used.

[JonasToth]

In D55595#1328154, @steveire wrote:

FYI, CMake target property INTERFACE_SOURCES is designed to make this easy.

For each module you would generate a file containing

extern volatile int ${MODULE_NAME}ModuleAnchorSource;
static int LLVM_ATTRIBUTE_UNUSED ${MODULE_NAME}ModuleAnchorDestination =
    ${MODULE_NAME}ModuleAnchorSource;

and then put that generated file in the INTERFACE_SOURCES of each module.

target_sources(${MODULE_NAME} INTERFACE ${THE_GENERATED_FILE}.cpp)

Then, you don't need to maintain it in C++ like this. It is DRY because the target_link_libraries entry for the library is what causes the symbol to be used.

That sounds like a better solution, but i think the current pattern is common in LLVM, maybe @aaron.ballman or @alexfh could share their opinion on this one?

[steveire]

Can you say where else it is common in LLVM? I'm curious. Maybe those places could be changed too.

[JonasToth]

In D55595#1328263, @steveire wrote:

Can you say where else it is common in LLVM? I'm curious. Maybe those places could be changed too.

My "is common" is not quantified, I have seen it before :)

From grepping "extern volatile":

• clang-tidy a lot
• clang/lib/Tooling/CompilationDatabase.cpp:398
• clang/lib/Tooling/Execution.cpp:100
• clang/tools/libclang/CIndex.cpp:8681
• clang/tools/libclang/CIndex.cpp:8675

Thats probably all places or is same idiom implementable with something else?

[JonasToth]

One thing: Could you please check the utility-scripts in clang-tidy that create new checks, if they need adjustments? Not sure if we have something in there that relies on the old structure.

[yvvan]

In D55595#1329647, @JonasToth wrote:

One thing: Could you please check the utility-scripts in clang-tidy that create new checks, if they need adjustments? Not sure if we have something in there that relies on the old structure.

As far as I see these scripts do not touch 'tool' or 'plugin' folders at all, only the specific module, docs and tests.

[JonasToth]

LGTM, chatted with steveire on IRC: blocking this for a better cmake based solution makes no sense. So your free to commit :)

[yvvan]

clang-tidy/plugin/ClangTidyPlugin.cpp

-91

It seems it had to go after #include "clang/Config/config.h" to have MPI checks enabled...

[lebedev.ri]

clang-tidy/plugin/ClangTidyPlugin.cpp

-91

The includes should be auto-sorted by clang-format, so if that header needs some headers,
then it should include them, not hope they will already be included.

[yvvan]

clang-tidy/plugin/ClangTidyPlugin.cpp

-91

True. Will fix tomorrow asap.

[dyung]

I have reverted this in r349121 as it has been causing the PS4 bots to be red for hours now.

[dyung]

clang-tidy/ClangTidyForceLinker.h

12

Is there a reason that this header file does not use the standard header guards?

12

Sorry, this should not have been marked as done.

[yvvan]

clang-tidy/ClangTidyForceLinker.h

12

I'm adding them together with the include.

[yvvan]

clang-tidy/plugin/ClangTidyPlugin.cpp

-91

Damn, "config.h" is special and can only be included once.

clang-tidy/ClangTidyForceLinker.h

+#include "llvm/Support/Compiler.h"
+
+namespace clang {
+namespace tidy {
+
+// This anchor is used to force the linker to link the CERTModule.
+extern volatile int CERTModuleAnchorSource;
+static int LLVM_ATTRIBUTE_UNUSED CERTModuleAnchorDestination =
+    CERTModuleAnchorSource;
+
+// This anchor is used to force the linker to link the AbseilModule.
+extern volatile int AbseilModuleAnchorSource;
+static int LLVM_ATTRIBUTE_UNUSED AbseilModuleAnchorDestination =
+    AbseilModuleAnchorSource;
+
+// This anchor is used to force the linker to link the BoostModule.
+extern volatile int BoostModuleAnchorSource;
+static int LLVM_ATTRIBUTE_UNUSED BoostModuleAnchorDestination =
+    BoostModuleAnchorSource;
+
+// This anchor is used to force the linker to link the BugproneModule.
+extern volatile int BugproneModuleAnchorSource;
+static int LLVM_ATTRIBUTE_UNUSED BugproneModuleAnchorDestination =
+    BugproneModuleAnchorSource;
+
+// This anchor is used to force the linker to link the LLVMModule.
+extern volatile int LLVMModuleAnchorSource;
+static int LLVM_ATTRIBUTE_UNUSED LLVMModuleAnchorDestination =
+    LLVMModuleAnchorSource;
+
+// This anchor is used to force the linker to link the CppCoreGuidelinesModule.
+extern volatile int CppCoreGuidelinesModuleAnchorSource;
+static int LLVM_ATTRIBUTE_UNUSED CppCoreGuidelinesModuleAnchorDestination =
+    CppCoreGuidelinesModuleAnchorSource;
+
+// This anchor is used to force the linker to link the FuchsiaModule.
+extern volatile int FuchsiaModuleAnchorSource;
+static int LLVM_ATTRIBUTE_UNUSED FuchsiaModuleAnchorDestination =
+    FuchsiaModuleAnchorSource;
+
+// This anchor is used to force the linker to link the GoogleModule.
+extern volatile int GoogleModuleAnchorSource;
+static int LLVM_ATTRIBUTE_UNUSED GoogleModuleAnchorDestination =
+    GoogleModuleAnchorSource;
+
+// This anchor is used to force the linker to link the AndroidModule.
+extern volatile int AndroidModuleAnchorSource;
+static int LLVM_ATTRIBUTE_UNUSED AndroidModuleAnchorDestination =
+    AndroidModuleAnchorSource;
+
+// This anchor is used to force the linker to link the MiscModule.
+extern volatile int MiscModuleAnchorSource;
+static int LLVM_ATTRIBUTE_UNUSED MiscModuleAnchorDestination =
+    MiscModuleAnchorSource;
+
+// This anchor is used to force the linker to link the ModernizeModule.
+extern volatile int ModernizeModuleAnchorSource;
+static int LLVM_ATTRIBUTE_UNUSED ModernizeModuleAnchorDestination =
+    ModernizeModuleAnchorSource;
+
+#if CLANG_ENABLE_STATIC_ANALYZER
+// This anchor is used to force the linker to link the MPIModule.
+extern volatile int MPIModuleAnchorSource;
+static int LLVM_ATTRIBUTE_UNUSED MPIModuleAnchorDestination =
+    MPIModuleAnchorSource;
+#endif
+
+// This anchor is used to force the linker to link the PerformanceModule.
+extern volatile int PerformanceModuleAnchorSource;
+static int LLVM_ATTRIBUTE_UNUSED PerformanceModuleAnchorDestination =
+    PerformanceModuleAnchorSource;
+
+// This anchor is used to force the linker to link the PortabilityModule.
+extern volatile int PortabilityModuleAnchorSource;
+static int LLVM_ATTRIBUTE_UNUSED PortabilityModuleAnchorDestination =
+    PortabilityModuleAnchorSource;
+
+// This anchor is used to force the linker to link the ReadabilityModule.
+extern volatile int ReadabilityModuleAnchorSource;
+static int LLVM_ATTRIBUTE_UNUSED ReadabilityModuleAnchorDestination =
+    ReadabilityModuleAnchorSource;
+
+// This anchor is used to force the linker to link the ObjCModule.
+extern volatile int ObjCModuleAnchorSource;
+static int LLVM_ATTRIBUTE_UNUSED ObjCModuleAnchorDestination =
+    ObjCModuleAnchorSource;
+
+// This anchor is used to force the linker to link the HICPPModule.
+extern volatile int HICPPModuleAnchorSource;
+static int LLVM_ATTRIBUTE_UNUSED HICPPModuleAnchorDestination =
+    HICPPModuleAnchorSource;
+
+// This anchor is used to force the linker to link the ZirconModule.
+extern volatile int ZirconModuleAnchorSource;
+static int LLVM_ATTRIBUTE_UNUSED ZirconModuleAnchorDestination =
+    ZirconModuleAnchorSource;
+
+} // namespace tidy
+} // namespace clang

clang-tidy/plugin/ClangTidyPlugin.cpp

 //===- ClangTidyPlugin.cpp - clang-tidy as a clang plugin -----------------===//
 //
 //                     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 "../ClangTidyForceLinker.h"
 #include "../ClangTidyModule.h"
 #include "clang/Config/config.h"
 #include "clang/Frontend/CompilerInstance.h"
 #include "clang/Frontend/FrontendPluginRegistry.h"
 #include "clang/Frontend/MultiplexConsumer.h"
 
 namespace clang {
 namespace tidy {

 } // namespace clang
 
 // This anchor is used to force the linker to link in the generated object file
 // and thus register the clang-tidy plugin.
 volatile int ClangTidyPluginAnchorSource = 0;
 
 static clang::FrontendPluginRegistry::Add<clang::tidy::ClangTidyPluginAction>
     X("clang-tidy", "clang-tidy");
-
-namespace clang {
-namespace tidy {
-
-// This anchor is used to force the linker to link the AbseilModule.
-extern volatile int AbseilModuleAnchorSource;
-static int LLVM_ATTRIBUTE_UNUSED AbseilModuleAnchorDestination =
-    AbseilModuleAnchorSource;
-
-// This anchor is used to force the linker to link the AndroidModule.
-extern volatile int AndroidModuleAnchorSource;
-static int LLVM_ATTRIBUTE_UNUSED AndroidModuleAnchorDestination =
-    AndroidModuleAnchorSource;
-
-// This anchor is used to force the linker to link the BoostModule.
-extern volatile int BoostModuleAnchorSource;
-static int LLVM_ATTRIBUTE_UNUSED BoostModuleAnchorDestination =
-    BoostModuleAnchorSource;
-
-// This anchor is used to force the linker to link the CERTModule.
-extern volatile int CERTModuleAnchorSource;
-static int LLVM_ATTRIBUTE_UNUSED CERTModuleAnchorDestination =
-    CERTModuleAnchorSource;
-
-// This anchor is used to force the linker to link the CppCoreGuidelinesModule.
-extern volatile int CppCoreGuidelinesModuleAnchorSource;
-static int LLVM_ATTRIBUTE_UNUSED CppCoreGuidelinesModuleAnchorDestination =
-    CppCoreGuidelinesModuleAnchorSource;
-
-// This anchor is used to force the linker to link the FuchsiaModule.
-extern volatile int FuchsiaModuleAnchorSource;
-static int LLVM_ATTRIBUTE_UNUSED FuchsiaModuleAnchorDestination =
-    FuchsiaModuleAnchorSource;
-
-// This anchor is used to force the linker to link the GoogleModule.
-extern volatile int GoogleModuleAnchorSource;
-static int LLVM_ATTRIBUTE_UNUSED GoogleModuleAnchorDestination =
-    GoogleModuleAnchorSource;
-
-// This anchor is used to force the linker to link the HICPPModule.
-extern volatile int HICPPModuleAnchorSource;
-static int LLVM_ATTRIBUTE_UNUSED HICPPModuleAnchorDestination =
-    HICPPModuleAnchorSource;
-
-// This anchor is used to force the linker to link the LLVMModule.
-extern volatile int LLVMModuleAnchorSource;
-static int LLVM_ATTRIBUTE_UNUSED LLVMModuleAnchorDestination =
-    LLVMModuleAnchorSource;
-
-// This anchor is used to force the linker to link the MiscModule.
-extern volatile int MiscModuleAnchorSource;
-static int LLVM_ATTRIBUTE_UNUSED MiscModuleAnchorDestination =
-    MiscModuleAnchorSource;
-
-// This anchor is used to force the linker to link the ModernizeModule.
-extern volatile int ModernizeModuleAnchorSource;
-static int LLVM_ATTRIBUTE_UNUSED ModernizeModuleAnchorDestination =
-    ModernizeModuleAnchorSource;
-
-#if CLANG_ENABLE_STATIC_ANALYZER
-// This anchor is used to force the linker to link the MPIModule.
-extern volatile int MPIModuleAnchorSource;
-static int LLVM_ATTRIBUTE_UNUSED MPIModuleAnchorDestination =
-    MPIModuleAnchorSource;
-#endif
-
-// This anchor is used to force the linker to link the ObjCModule.
-extern volatile int ObjCModuleAnchorSource;
-static int LLVM_ATTRIBUTE_UNUSED ObjCModuleAnchorDestination =
-    ObjCModuleAnchorSource;
-
-// This anchor is used to force the linker to link the PerformanceModule.
-extern volatile int PerformanceModuleAnchorSource;
-static int LLVM_ATTRIBUTE_UNUSED PerformanceModuleAnchorDestination =
-    PerformanceModuleAnchorSource;
-
-// This anchor is used to force the linker to link the PortabilityModule.
-extern volatile int PortabilityModuleAnchorSource;
-static int LLVM_ATTRIBUTE_UNUSED PortabilityModuleAnchorDestination =
-    PortabilityModuleAnchorSource;
-
-// This anchor is used to force the linker to link the ReadabilityModule.
-extern volatile int ReadabilityModuleAnchorSource;
-static int LLVM_ATTRIBUTE_UNUSED ReadabilityModuleAnchorDestination =
-    ReadabilityModuleAnchorSource;
-
-// This anchor is used to force the linker to link the ZirconModule.
-extern volatile int ZirconModuleAnchorSource;
-static int LLVM_ATTRIBUTE_UNUSED ZirconModuleAnchorDestination =
-    ZirconModuleAnchorSource;
-
-} // namespace tidy
-} // namespace clang

clang-tidy/tool/ClangTidyMain.cpp

 ///
 ///  This tool uses the Clang Tooling infrastructure, see
 ///    http://clang.llvm.org/docs/HowToSetupToolingForLLVM.html
 ///  for details on setting it up with LLVM source tree.
 ///
 //===----------------------------------------------------------------------===//
 
 #include "../ClangTidy.h"
+#include "../ClangTidyForceLinker.h"
 #include "clang/Config/config.h"
 #include "clang/Tooling/CommonOptionsParser.h"
 #include "llvm/Support/Process.h"
 #include "llvm/Support/Signals.h"
 #include "llvm/Support/TargetSelect.h"
 
 using namespace clang::ast_matchers;
 using namespace clang::driver;
if (FoundErrors) {
     if (!Quiet)
       llvm::errs() << "Found compiler error(s).\n";
     return 1;
   }
 
   return 0;
 }
 
-// This anchor is used to force the linker to link the CERTModule.
-extern volatile int CERTModuleAnchorSource;
-static int LLVM_ATTRIBUTE_UNUSED CERTModuleAnchorDestination =
-    CERTModuleAnchorSource;
-
-// This anchor is used to force the linker to link the AbseilModule.
-extern volatile int AbseilModuleAnchorSource;
-static int LLVM_ATTRIBUTE_UNUSED AbseilModuleAnchorDestination =
-    AbseilModuleAnchorSource;
-
-// This anchor is used to force the linker to link the BoostModule.
-extern volatile int BoostModuleAnchorSource;
-static int LLVM_ATTRIBUTE_UNUSED BoostModuleAnchorDestination =
-    BoostModuleAnchorSource;
-
-// This anchor is used to force the linker to link the BugproneModule.
-extern volatile int BugproneModuleAnchorSource;
-static int LLVM_ATTRIBUTE_UNUSED BugproneModuleAnchorDestination =
-    BugproneModuleAnchorSource;
-
-// This anchor is used to force the linker to link the LLVMModule.
-extern volatile int LLVMModuleAnchorSource;
-static int LLVM_ATTRIBUTE_UNUSED LLVMModuleAnchorDestination =
-    LLVMModuleAnchorSource;
-
-// This anchor is used to force the linker to link the CppCoreGuidelinesModule.
-extern volatile int CppCoreGuidelinesModuleAnchorSource;
-static int LLVM_ATTRIBUTE_UNUSED CppCoreGuidelinesModuleAnchorDestination =
-    CppCoreGuidelinesModuleAnchorSource;
-
-// This anchor is used to force the linker to link the FuchsiaModule.
-extern volatile int FuchsiaModuleAnchorSource;
-static int LLVM_ATTRIBUTE_UNUSED FuchsiaModuleAnchorDestination =
-    FuchsiaModuleAnchorSource;
-
-// This anchor is used to force the linker to link the GoogleModule.
-extern volatile int GoogleModuleAnchorSource;
-static int LLVM_ATTRIBUTE_UNUSED GoogleModuleAnchorDestination =
-    GoogleModuleAnchorSource;
-
-// This anchor is used to force the linker to link the AndroidModule.
-extern volatile int AndroidModuleAnchorSource;
-static int LLVM_ATTRIBUTE_UNUSED AndroidModuleAnchorDestination =
-    AndroidModuleAnchorSource;
-
-// This anchor is used to force the linker to link the MiscModule.
-extern volatile int MiscModuleAnchorSource;
-static int LLVM_ATTRIBUTE_UNUSED MiscModuleAnchorDestination =
-    MiscModuleAnchorSource;
-
-// This anchor is used to force the linker to link the ModernizeModule.
-extern volatile int ModernizeModuleAnchorSource;
-static int LLVM_ATTRIBUTE_UNUSED ModernizeModuleAnchorDestination =
-    ModernizeModuleAnchorSource;
-
-#if CLANG_ENABLE_STATIC_ANALYZER
-// This anchor is used to force the linker to link the MPIModule.
-extern volatile int MPIModuleAnchorSource;
-static int LLVM_ATTRIBUTE_UNUSED MPIModuleAnchorDestination =
-    MPIModuleAnchorSource;
-#endif
-
-// This anchor is used to force the linker to link the PerformanceModule.
-extern volatile int PerformanceModuleAnchorSource;
-static int LLVM_ATTRIBUTE_UNUSED PerformanceModuleAnchorDestination =
-    PerformanceModuleAnchorSource;
-
-// This anchor is used to force the linker to link the PortabilityModule.
-extern volatile int PortabilityModuleAnchorSource;
-static int LLVM_ATTRIBUTE_UNUSED PortabilityModuleAnchorDestination =
-    PortabilityModuleAnchorSource;
-
-// This anchor is used to force the linker to link the ReadabilityModule.
-extern volatile int ReadabilityModuleAnchorSource;
-static int LLVM_ATTRIBUTE_UNUSED ReadabilityModuleAnchorDestination =
-    ReadabilityModuleAnchorSource;
-
-// This anchor is used to force the linker to link the ObjCModule.
-extern volatile int ObjCModuleAnchorSource;
-static int LLVM_ATTRIBUTE_UNUSED ObjCModuleAnchorDestination =
-    ObjCModuleAnchorSource;
-
-// This anchor is used to force the linker to link the HICPPModule.
-extern volatile int HICPPModuleAnchorSource;
-static int LLVM_ATTRIBUTE_UNUSED HICPPModuleAnchorDestination =
-    HICPPModuleAnchorSource;
-
-// This anchor is used to force the linker to link the ZirconModule.
-extern volatile int ZirconModuleAnchorSource;
-static int LLVM_ATTRIBUTE_UNUSED ZirconModuleAnchorDestination =
-    ZirconModuleAnchorSource;
-
 } // namespace tidy
 } // namespace clang
 
 int main(int argc, const char **argv) {
   return clang::tidy::clangTidyMain(argc, argv);
 }