From 188592ff08ad552427083124cad12eb0ddd798ba Mon Sep 17 00:00:00 2001
From: Petr Hosek <phosek@google.com>
Date: Mon, 29 Mar 2021 13:07:39 -0700
Subject: [PATCH] Revert "[CMake] Use write_basic_package_version_file for
 LLVM"

This reverts commit 3001d080c813da20b329303bf8f45451480e5905 which
seems to have introduced a race condition that's failing the build
in some cases.
---
 llvm/cmake/modules/CMakeLists.txt             | 12 +++++-------
 llvm/cmake/modules/LLVMConfigVersion.cmake.in | 13 +++++++++++++
 2 files changed, 18 insertions(+), 7 deletions(-)
 create mode 100644 llvm/cmake/modules/LLVMConfigVersion.cmake.in

diff --git a/llvm/cmake/modules/CMakeLists.txt b/llvm/cmake/modules/CMakeLists.txt
index 8276126..505dc9a 100644
--- a/llvm/cmake/modules/CMakeLists.txt
+++ b/llvm/cmake/modules/CMakeLists.txt
@@ -127,13 +127,11 @@ configure_file(
   ${CMAKE_CURRENT_BINARY_DIR}/CMakeFiles/LLVMConfig.cmake
   @ONLY)
 
-# Generate LLVMConfigVersion.cmake for build tree (later copied to install tree).
-include(CMakePackageConfigHelpers)
-write_basic_package_version_file(
-  "${llvm_cmake_builddir}/LLVMConfigVersion.cmake"
-  VERSION "${PACKAGE_VERSION}"
-  COMPATIBILITY SameMinorVersion
-)
+# Generate LLVMConfigVersion.cmake for build and install tree.
+configure_file(
+  LLVMConfigVersion.cmake.in
+  ${llvm_cmake_builddir}/LLVMConfigVersion.cmake
+  @ONLY)
 
 if (NOT LLVM_INSTALL_TOOLCHAIN_ONLY)
   get_property(llvm_has_exports GLOBAL PROPERTY LLVM_HAS_EXPORTS)
diff --git a/llvm/cmake/modules/LLVMConfigVersion.cmake.in b/llvm/cmake/modules/LLVMConfigVersion.cmake.in
new file mode 100644
index 0000000..e9ac4ed
--- /dev/null
+++ b/llvm/cmake/modules/LLVMConfigVersion.cmake.in
@@ -0,0 +1,13 @@
+set(PACKAGE_VERSION "@PACKAGE_VERSION@")
+
+# LLVM is API-compatible only with matching major.minor versions
+# and patch versions not less than that requested.
+if("@LLVM_VERSION_MAJOR@.@LLVM_VERSION_MINOR@" VERSION_EQUAL
+    "${PACKAGE_FIND_VERSION_MAJOR}.${PACKAGE_FIND_VERSION_MINOR}"
+   AND NOT "@LLVM_VERSION_PATCH@" VERSION_LESS "${PACKAGE_FIND_VERSION_PATCH}")
+  set(PACKAGE_VERSION_COMPATIBLE 1)
+  if("@LLVM_VERSION_PATCH@" VERSION_EQUAL
+      "${PACKAGE_FIND_VERSION_PATCH}")
+    set(PACKAGE_VERSION_EXACT 1)
+  endif()
+endif()
-- 
2.7.4