Revert "enable plugins for clang-tidy"

This reverts commit 36892727e4f19a60778e371d78f8fb09d8122c85 which
breaks the build when LLVM_INSTALL_TOOLCHAIN_ONLY is enabled with:

  CMake Error at cmake/modules/AddLLVM.cmake:683 (add_dependencies):
  The dependency target "clang-tidy-headers" of target "CTTestTidyModule"
  does not exist.

9 files changed, 2 insertions, 139 deletions

diff --git a/clang-tools-extra/clang-tidy/tool/CMakeLists.txt b/clang-tools-extra/clang-tidy/tool/CMakeLists.txt
index 3ce552872015..4b8c93801501 100644
--- a/clang-tools-extra/clang-tidy/tool/CMakeLists.txt
+++ b/clang-tools-extra/clang-tidy/tool/CMakeLists.txt
@@ -29,17 +29,11 @@ clang_target_link_libraries(clangTidyMain
   clangToolingCore
   )
 
-# Support plugins.
-if(CLANG_PLUGIN_SUPPORT)
-  set(support_plugins SUPPORT_PLUGINS)
-endif()
-
 add_clang_tool(clang-tidy
   ClangTidyToolMain.cpp
-
-  DEPENDS
+  )
+add_dependencies(clang-tidy
   clang-resource-headers
-  ${support_plugins}
   )
 clang_target_link_libraries(clang-tidy
   PRIVATE
@@ -56,9 +50,6 @@ target_link_libraries(clang-tidy
   ${ALL_CLANG_TIDY_CHECKS}
   )
 
-if(CLANG_PLUGIN_SUPPORT)
-  export_executable_symbols_for_plugins(clang-tidy)
-endif()
 
 install(PROGRAMS clang-tidy-diff.py
   DESTINATION "${CMAKE_INSTALL_DATADIR}/clang"
diff --git a/clang-tools-extra/clang-tidy/tool/ClangTidyMain.cpp b/clang-tools-extra/clang-tidy/tool/ClangTidyMain.cpp
index 1b0010bdd62a..6147d90eb10b 100644
--- a/clang-tools-extra/clang-tidy/tool/ClangTidyMain.cpp
+++ b/clang-tools-extra/clang-tidy/tool/ClangTidyMain.cpp
@@ -20,7 +20,6 @@
 #include "../GlobList.h"
 #include "clang/Tooling/CommonOptionsParser.h"
 #include "llvm/Support/InitLLVM.h"
-#include "llvm/Support/PluginLoader.h"
 #include "llvm/Support/Process.h"
 #include "llvm/Support/Signals.h"
 #include "llvm/Support/TargetSelect.h"
@@ -387,11 +386,6 @@ getVfsFromFile(const std::string &OverlayFile,
 
 int clangTidyMain(int argc, const char **argv) {
   llvm::InitLLVM X(argc, argv);
-
-  // Enable help for -load option, if plugins are enabled.
-  if (cl::Option *LoadOpt = cl::getRegisteredOptions().lookup("load"))
-    LoadOpt->addCategory(ClangTidyCategory);
-
   llvm::Expected<CommonOptionsParser> OptionsParser =
       CommonOptionsParser::create(argc, argv, ClangTidyCategory,
                                   cl::ZeroOrMore);
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index 115855c759d6..dbbe79c1aac2 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -76,8 +76,6 @@ Improvements to clang-tidy
 - Added support for `NOLINTBEGIN` ... `NOLINTEND` comments to suppress
   Clang-Tidy warnings over multiple lines.
 
-- Added support for external plugin checks with `-load`.
-
 New checks
 ^^^^^^^^^^
 
diff --git a/clang-tools-extra/docs/clang-tidy/Contributing.rst b/clang-tools-extra/docs/clang-tidy/Contributing.rst
index b1771574950a..b9eb0e7627cc 100644
--- a/clang-tools-extra/docs/clang-tidy/Contributing.rst
+++ b/clang-tools-extra/docs/clang-tidy/Contributing.rst
@@ -634,26 +634,6 @@ This keeps the test directory from getting cluttered.
 .. _FileCheck: https://llvm.org/docs/CommandGuide/FileCheck.html
 .. _test/clang-tidy/google-readability-casting.cpp: https://reviews.llvm.org/diffusion/L/browse/clang-tools-extra/trunk/test/clang-tidy/google-readability-casting.cpp
 
-Out-of-tree check plugins
--------------------------
-
-Developing an out-of-tree check as a plugin largely follows the steps
-outlined above. The plugin is a shared library whose code lives outside
-the clang-tidy build system. Build and link this shared library against
-LLVM as done for other kinds of Clang plugins.
-
-The plugin can be loaded by passing `-load` to `clang-tidy` in addition to the
-names of the checks to enable.
-
-.. code-block:: console
-
-  $ clang-tidy --checks=-*,my-explicit-constructor -list-checks -load myplugin.so
-
-There is no expectations regarding ABI and API stability, so the plugin must be
-compiled against the version of clang-tidy that will be loading the plugin.
-
-The plugins can use threads, TLS, or any other facilities available to in-tree
-code which is accessible from the external headers.
 
 Running clang-tidy on LLVM
 --------------------------
diff --git a/clang-tools-extra/docs/clang-tidy/index.rst b/clang-tools-extra/docs/clang-tidy/index.rst
index c76259e02f8d..3231b1528efc 100644
--- a/clang-tools-extra/docs/clang-tidy/index.rst
+++ b/clang-tools-extra/docs/clang-tidy/index.rst
@@ -218,15 +218,6 @@ An overview of all the command-line options:
     --list-checks                  -
                                      List all enabled checks and exit. Use with
                                      -checks=* to list all available checks.
-    -load=<plugin>                 -
-                                     Load the dynamic object ``plugin``. This
-                                     object should register new static analyzer
-                                     or clang-tidy passes. Once loaded, the
-                                     object will add new command line options
-                                     to run various analyses. To see the new
-                                     complete list of passes, use the
-                                     :option:`--list-checks` and
-                                     :option:`-load` options together.
     -p=<string>                    - Build path
     --quiet                        -
                                      Run clang-tidy in quiet mode. This suppresses
diff --git a/clang-tools-extra/test/CMakeLists.txt b/clang-tools-extra/test/CMakeLists.txt
index e7a44dfd93fe..06be00015223 100644
--- a/clang-tools-extra/test/CMakeLists.txt
+++ b/clang-tools-extra/test/CMakeLists.txt
@@ -17,7 +17,6 @@ string(REPLACE ${CMAKE_CFG_INTDIR} ${LLVM_BUILD_MODE} CLANG_TOOLS_DIR ${LLVM_RUN
 
 llvm_canonicalize_cmake_booleans(
   CLANG_TIDY_ENABLE_STATIC_ANALYZER
-  LLVM_ENABLE_PLUGINS
   )
 
 configure_lit_site_cfg(
@@ -79,22 +78,6 @@ foreach(dep ${LLVM_UTILS_DEPS})
   endif()
 endforeach()
 
-llvm_add_library(
-    CTTestTidyModule
-    MODULE clang-tidy/CTTestTidyModule.cpp
-    PLUGIN_TOOL clang-tidy
-    DEPENDS clang-tidy-headers)
-
-if(TARGET CTTestTidyModule)
-    list(APPEND CLANG_TOOLS_TEST_DEPS CTTestTidyModule LLVMHello)
-    target_include_directories(CTTestTidyModule PUBLIC BEFORE "${CLANG_TOOLS_SOURCE_DIR}")
-    if(LLVM_ENABLE_PLUGINS AND (WIN32 OR CYGWIN))
-      set(LLVM_LINK_COMPONENTS
-        Support
-      )
-    endif()
-endif()
-
 add_lit_testsuite(check-clang-tools "Running the Clang extra tools' regression tests"
   ${CMAKE_CURRENT_BINARY_DIR}
   DEPENDS ${CLANG_TOOLS_TEST_DEPS}
diff --git a/clang-tools-extra/test/clang-tidy/CTTestTidyModule.cpp b/clang-tools-extra/test/clang-tidy/CTTestTidyModule.cpp
deleted file mode 100644
index c66a94f458cf..000000000000
--- a/clang-tools-extra/test/clang-tidy/CTTestTidyModule.cpp
+++ /dev/null
@@ -1,66 +0,0 @@
-// REQUIRES: plugins
-// RUN: clang-tidy -checks='-*,mytest*' --list-checks -load %llvmshlibdir/CTTestTidyModule%pluginext -load %llvmshlibdir/LLVMHello%pluginext | FileCheck --check-prefix=CHECK-LIST %s
-// CHECK-LIST: Enabled checks:
-// CHECK-LIST-NEXT:    mytest1
-// CHECK-LIST-NEXT:    mytest2
-// RUN: clang-tidy -checks='-*,mytest*,misc-definitions-in-headers' -load %llvmshlibdir/CTTestTidyModule%pluginext /dev/null -- -xc 2>&1 | FileCheck %s
-// CHECK: 3 warnings generated.
-// CHECK-NEXT: warning: mytest success [misc-definitions-in-headers,mytest1,mytest2]
-
-#include "clang-tidy/ClangTidy.h"
-#include "clang-tidy/ClangTidyCheck.h"
-#include "clang-tidy/ClangTidyModule.h"
-#include "clang-tidy/ClangTidyModuleRegistry.h"
-#include "clang/AST/ASTContext.h"
-#include "clang/ASTMatchers/ASTMatchFinder.h"
-
-using namespace clang;
-using namespace clang::tidy;
-using namespace clang::ast_matchers;
-
-namespace {
-class MyTestCheck : public ClangTidyCheck {
-
-public:
-  MyTestCheck(StringRef Name, ClangTidyContext *Context)
-      : ClangTidyCheck(Name, Context) {}
-
-  void registerMatchers(ast_matchers::MatchFinder *Finder) override {
-    Finder->addMatcher(translationUnitDecl().bind("tu"), this);
-  }
-
-  void check(const ast_matchers::MatchFinder::MatchResult &Result) override {
-    auto S = Result.Nodes.getNodeAs<TranslationUnitDecl>("tu");
-    if (S)
-      diag("mytest success");
-  }
-
-private:
-};
-
-class CTTestModule : public ClangTidyModule {
-public:
-  void addCheckFactories(ClangTidyCheckFactories &CheckFactories) override {
-    CheckFactories.registerCheck<MyTestCheck>("mytest1");
-    CheckFactories.registerCheck<MyTestCheck>("mytest2");
-    // intentionally collide with an existing test name, overriding it
-    CheckFactories.registerCheck<MyTestCheck>("misc-definitions-in-headers");
-  }
-};
-} // namespace
-
-namespace tidy1 {
-// Register the CTTestTidyModule using this statically initialized variable.
-static ClangTidyModuleRegistry::Add<::CTTestModule>
-    X("mytest-module", "Adds my checks.");
-} // namespace tidy1
-
-namespace tidy2 {
-// intentionally collide with an existing test group name, merging with it
-static ClangTidyModuleRegistry::Add<::CTTestModule>
-    X("misc-module", "Adds miscellaneous lint checks.");
-} // namespace tidy2
-
-// This anchor is used to force the linker to link in the generated object file
-// and thus register the CTTestModule.
-volatile int CTTestModuleAnchorSource = 0;
diff --git a/clang-tools-extra/test/lit.cfg.py b/clang-tools-extra/test/lit.cfg.py
index 858e42ace2a8..24cabd823844 100644
--- a/clang-tools-extra/test/lit.cfg.py
+++ b/clang-tools-extra/test/lit.cfg.py
@@ -149,9 +149,3 @@ clangd_benchmarks_dir = os.path.join(os.path.dirname(config.clang_tools_dir),
                                      "clangd", "benchmarks")
 config.substitutions.append(('%clangd-benchmark-dir',
                              '%s' % (clangd_benchmarks_dir)))
-config.substitutions.append(('%llvmshlibdir', config.clang_libs_dir))
-config.substitutions.append(('%pluginext', config.llvm_plugin_ext))
-
-# Plugins (loadable modules)
-if config.has_plugins and config.llvm_plugin_ext:
-    config.available_features.add('plugins')
diff --git a/clang-tools-extra/test/lit.site.cfg.py.in b/clang-tools-extra/test/lit.site.cfg.py.in
index 81d4ffa8b393..f8300c1dd39d 100644
--- a/clang-tools-extra/test/lit.site.cfg.py.in
+++ b/clang-tools-extra/test/lit.site.cfg.py.in
@@ -4,7 +4,6 @@ import sys
 
 config.llvm_tools_dir = "@LLVM_TOOLS_DIR@"
 config.llvm_libs_dir = "@LLVM_LIBS_DIR@"
-config.llvm_plugin_ext = "@LLVM_PLUGIN_EXT@"
 config.lit_tools_dir = "@LLVM_LIT_TOOLS_DIR@"
 config.clang_tools_binary_dir = "@CLANG_TOOLS_BINARY_DIR@"
 config.clang_tools_dir = "@CLANG_TOOLS_DIR@"
@@ -12,7 +11,6 @@ config.clang_libs_dir = "@SHLIBDIR@"
 config.python_executable = "@Python3_EXECUTABLE@"
 config.target_triple = "@TARGET_TRIPLE@"
 config.clang_tidy_staticanalyzer = @CLANG_TIDY_ENABLE_STATIC_ANALYZER@
-config.has_plugins = @LLVM_ENABLE_PLUGINS@
 
 # Support substitution of the tools and libs dirs with user parameters. This is
 # used when we can't determine the tool dir at configuration time.