[flang-commits] [flang] af80568 - [flang][cmake] Improve how CLANG_DIR is handled

[Andrzej Warzynski via flang-commits]

Author: Andrzej Warzynski
Date: 2021-03-23T15:14:51Z
New Revision: af8056889ac9913c587293fd68503b4883dab558

URL: https://github.com/llvm/llvm-project/commit/af8056889ac9913c587293fd68503b4883dab558
DIFF: https://github.com/llvm/llvm-project/commit/af8056889ac9913c587293fd68503b4883dab558.diff

LOG: [flang][cmake] Improve how CLANG_DIR is handled

* Added a sanity check with `Clang_FOUND` to verify that find_package
succeeded
* Made sure that find_package won't use any of CMake's standard paths
to guarantee that only the path provided with CLANG_DIR is considered
(implemented through NO_DEFAULT_PATH)
* Made the call to get_filename_component more explicit (so that it is
clear what the base directory is)
* Updated comments to clarify what CLANG_DIR means

Differential Revision: https://reviews.llvm.org/D99088

Added: 
    

Modified: 
    flang/CMakeLists.txt

Removed: 
    


################################################################################
diff  --git a/flang/CMakeLists.txt b/flang/CMakeLists.txt
index 33e5521f6d5b..1318eafec7c3 100644
--- a/flang/CMakeLists.txt
+++ b/flang/CMakeLists.txt
@@ -48,9 +48,23 @@ if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
   list(APPEND CMAKE_MODULE_PATH ${LLVM_DIR_ABSOLUTE})
 
   if(FLANG_BUILD_NEW_DRIVER)
+    # Users might specify a path to CLANG_DIR that's:
+    #   * a full path, or
+    #   * a path relative to the path of this script.
+    # Append the absolute path to CLANG_DIR so that find_package works in both
+    # cases.
+    get_filename_component(
+      CLANG_DIR_ABSOLUTE
+      ${CLANG_DIR}
+      REALPATH
+      CMAKE_CURRENT_SOURCE_DIR)
+    list(APPEND CMAKE_MODULE_PATH ${CLANG_DIR_ABSOLUTE})
+
     # TODO: Remove when libclangDriver is lifted out of Clang
-    list(APPEND CMAKE_MODULE_PATH ${CLANG_DIR})
-    find_package(Clang REQUIRED HINTS "${CLANG_DIR}")
+    find_package(Clang REQUIRED PATHS "${CLANG_DIR_ABSOLUTE}" NO_DEFAULT_PATH)
+    if (NOT Clang_FOUND)
+      message(FATAL_ERROR "Failed to find Clang")
+    endif()
   endif()
 
   # If LLVM links to zlib we need the imported targets so we can too.