[clang] Only use major version in resource dir

This causes unnecessary churn for downstreams.

For the full discussion, see https://discourse.llvm.org/t/should-we-continue-embed-the-full-llvm-version-in-lib-clang/62094

Differential Revision: https://reviews.llvm.org/D125860

clang/docs/ReleaseNotes.rst

@@ -176,6 +176,11 @@ code bases.
       g(42);
     }
 
+- Clang's resource dir used to include the full clang version. It will now
+  include only the major version. The new resource directory is
+  ``$prefix/lib/clang/$CLANG_MAJOR_VERSION`` and can be queried using
+  ``clang -print-resource-dir``, just like before.
+
 What's New in Clang |release|?
 ==============================
 Some of the major new features and improvements to Clang are listed

clang/include/clang/Basic/Version.inc.in

@@ -1,5 +1,6 @@
 #define CLANG_VERSION @CLANG_VERSION@
 #define CLANG_VERSION_STRING "@CLANG_VERSION@"
 #define CLANG_VERSION_MAJOR @CLANG_VERSION_MAJOR@
+#define CLANG_VERSION_MAJOR_STRING "@CLANG_VERSION_MAJOR@"
 #define CLANG_VERSION_MINOR @CLANG_VERSION_MINOR@
 #define CLANG_VERSION_PATCHLEVEL @CLANG_VERSION_PATCHLEVEL@

clang/lib/Driver/Driver.cpp

@@ -182,7 +182,7 @@ std::string Driver::GetResourcesPath(StringRef BinaryPath,
     // ../lib gets us to lib/ in both cases.
     P = llvm::sys::path::parent_path(Dir);
     llvm::sys::path::append(P, CLANG_INSTALL_LIBDIR_BASENAME, "clang",
-                            CLANG_VERSION_STRING);
+                            CLANG_VERSION_MAJOR_STRING);
   }
 
   return std::string(P.str());

clang/lib/Headers/CMakeLists.txt

@@ -281,7 +281,7 @@ set(openmp_wrapper_files
   openmp_wrappers/new
 )
 
-set(output_dir ${LLVM_LIBRARY_OUTPUT_INTDIR}/clang/${CLANG_VERSION}/include)
+set(output_dir ${LLVM_LIBRARY_OUTPUT_INTDIR}/clang/${CLANG_VERSION_MAJOR}/include)
 set(out_files)
 set(generated_files)
 
@@ -434,7 +434,7 @@ add_header_target("openmp-resource-headers" ${openmp_wrapper_files})
 add_header_target("windows-resource-headers" ${windows_only_files})
 add_header_target("utility-resource-headers" ${utility_files})
 
-set(header_install_dir lib${LLVM_LIBDIR_SUFFIX}/clang/${CLANG_VERSION}/include)
+set(header_install_dir lib${LLVM_LIBDIR_SUFFIX}/clang/${CLANG_VERSION_MAJOR}/include)
 
 #############################################################
 # Install rules for the catch-all clang-resource-headers target

clang/lib/Tooling/CMakeLists.txt

@@ -60,7 +60,7 @@ else()
       $<TARGET_FILE:clang-ast-dump>
         # Skip this in debug mode because parsing AST.h is too slow
         --skip-processing=${skip_expensive_processing}
-        -I ${LLVM_BINARY_DIR}/lib/clang/${CLANG_VERSION}/include
+        -I ${LLVM_BINARY_DIR}/lib/clang/${CLANG_VERSION_MAJOR}/include
         -I ${CLANG_SOURCE_DIR}/include
         -I ${LLVM_BINARY_DIR}/tools/clang/include
         -I ${LLVM_BINARY_DIR}/include

clang/runtime/CMakeLists.txt

@@ -82,9 +82,9 @@ if(LLVM_BUILD_EXTERNAL_COMPILER_RT AND EXISTS ${COMPILER_RT_SRC_ROOT}/)
                -DCMAKE_CXX_COMPILER_LAUNCHER=${CMAKE_CXX_COMPILER_LAUNCHER}
                -DLLVM_CONFIG_PATH=${LLVM_RUNTIME_OUTPUT_INTDIR}/llvm-config
                -DLLVM_LIT_ARGS=${LLVM_LIT_ARGS}
-               -DCOMPILER_RT_OUTPUT_DIR=${LLVM_LIBRARY_OUTPUT_INTDIR}/clang/${CLANG_VERSION}
+               -DCOMPILER_RT_OUTPUT_DIR=${LLVM_LIBRARY_OUTPUT_INTDIR}/clang/${CLANG_VERSION_MAJOR}
                -DCOMPILER_RT_EXEC_OUTPUT_DIR=${LLVM_RUNTIME_OUTPUT_INTDIR}
-               -DCOMPILER_RT_INSTALL_PATH:PATH=lib${LLVM_LIBDIR_SUFFIX}/clang/${CLANG_VERSION}
+               -DCOMPILER_RT_INSTALL_PATH:PATH=lib${LLVM_LIBDIR_SUFFIX}/clang/${CLANG_VERSION_MAJOR}
                -DCOMPILER_RT_INCLUDE_TESTS=${LLVM_INCLUDE_TESTS}
                -DCMAKE_INSTALL_PREFIX=${CMAKE_INSTALL_PREFIX}
                -DLLVM_LIBDIR_SUFFIX=${LLVM_LIBDIR_SUFFIX}

compiler-rt/cmake/base-config-ix.cmake

@@ -38,14 +38,14 @@ endif()
 
 if (LLVM_TREE_AVAILABLE)
   # Compute the Clang version from the LLVM version.
-  # FIXME: We should be able to reuse CLANG_VERSION variable calculated
+  # FIXME: We should be able to reuse CLANG_VERSION_MAJOR variable calculated
   #        in Clang cmake files, instead of copying the rules here.
-  string(REGEX MATCH "[0-9]+\\.[0-9]+(\\.[0-9]+)?" CLANG_VERSION
+  string(REGEX MATCH "^[0-9]+" CLANG_VERSION_MAJOR
          ${PACKAGE_VERSION})
   # Setup the paths where compiler-rt runtimes and headers should be stored.
-  set(COMPILER_RT_OUTPUT_DIR ${LLVM_LIBRARY_OUTPUT_INTDIR}/clang/${CLANG_VERSION})
+  set(COMPILER_RT_OUTPUT_DIR ${LLVM_LIBRARY_OUTPUT_INTDIR}/clang/${CLANG_VERSION_MAJOR})
   set(COMPILER_RT_EXEC_OUTPUT_DIR ${LLVM_RUNTIME_OUTPUT_INTDIR})
-  set(COMPILER_RT_INSTALL_PATH lib${LLVM_LIBDIR_SUFFIX}/clang/${CLANG_VERSION})
+  set(COMPILER_RT_INSTALL_PATH lib${LLVM_LIBDIR_SUFFIX}/clang/${CLANG_VERSION_MAJOR})
   option(COMPILER_RT_INCLUDE_TESTS "Generate and build compiler-rt unit tests."
          ${LLVM_INCLUDE_TESTS})
   option(COMPILER_RT_ENABLE_WERROR "Fail and stop if warning is triggered"

lldb/source/Plugins/ExpressionParser/Clang/ClangHost.cpp

@@ -55,7 +55,7 @@ static bool DefaultComputeClangResourceDirectory(FileSpec &lldb_shlib_spec,
   static const llvm::StringRef kResourceDirSuffixes[] = {
       // LLVM.org's build of LLDB uses the clang resource directory placed
       // in $install_dir/lib{,64}/clang/$clang_version.
-      CLANG_INSTALL_LIBDIR_BASENAME "/clang/" CLANG_VERSION_STRING,
+      CLANG_INSTALL_LIBDIR_BASENAME "/clang/" CLANG_VERSION_MAJOR_STRING,
       // swift-lldb uses the clang resource directory copied from swift, which
       // by default is placed in $install_dir/lib{,64}/lldb/clang. LLDB places
       // it there, so we use LLDB_INSTALL_LIBDIR_BASENAME.

lldb/unittests/Expression/ClangParserTest.cpp

@@ -38,10 +38,11 @@ TEST_F(ClangHostTest, ComputeClangResourceDirectory) {
 #if !defined(_WIN32)
   std::string path_to_liblldb = "/foo/bar/lib/";
   std::string path_to_clang_dir =
-      "/foo/bar/" LLDB_INSTALL_LIBDIR_BASENAME "/clang/" CLANG_VERSION_STRING;
+      "/foo/bar/" LLDB_INSTALL_LIBDIR_BASENAME "/clang/" CLANG_VERSION_MAJOR_STRING;
 #else
   std::string path_to_liblldb = "C:\\foo\\bar\\lib";
-  std::string path_to_clang_dir = "C:\\foo\\bar\\lib\\clang\\" CLANG_VERSION_STRING;
+  std::string path_to_clang_dir =
+      "C:\\foo\\bar\\lib\\clang\\" CLANG_VERSION_MAJOR_STRING;
 #endif
   EXPECT_EQ(ComputeClangResourceDir(path_to_liblldb), path_to_clang_dir);
 

llvm/cmake/modules/LLVMExternalProjectUtils.cmake

@@ -255,9 +255,9 @@ function(llvm_ExternalProject_Add name source_dir)
     set(llvm_config_path ${LLVM_CONFIG_PATH})
 
     if(CMAKE_CXX_COMPILER_ID MATCHES "Clang")
-      string(REGEX MATCH "[0-9]+\\.[0-9]+(\\.[0-9]+)?" CLANG_VERSION
+      string(REGEX MATCH "^[0-9]+" CLANG_VERSION_MAJOR
              ${PACKAGE_VERSION})
-      set(resource_dir "${LLVM_LIBRARY_DIR}/clang/${CLANG_VERSION}")
+      set(resource_dir "${LLVM_LIBRARY_DIR}/clang/${CLANG_VERSION_MAJOR}")
       set(flag_types ASM C CXX MODULE_LINKER SHARED_LINKER EXE_LINKER)
       foreach(type ${flag_types})
         set(${type}_flag -DCMAKE_${type}_FLAGS=-resource-dir=${resource_dir})

polly/lib/External/isl/interface/extract_interface.cc

@@ -109,7 +109,7 @@ static llvm::cl::opt<string> OutputLanguage(llvm::cl::Required,
 	llvm::cl::value_desc("name"));
 
 static const char *ResourceDir =
-	CLANG_PREFIX "/lib/clang/" CLANG_VERSION_STRING;
+    CLANG_PREFIX "/lib/clang/" CLANG_VERSION_MAJOR_STRING;
 
 /* Does decl have an attribute of the following form?
  *