[PATCH] D79400: [CMAKE] Fix build failure when source directory is read only

[Pushpinder Singh via Phabricator via llvm-commits]

pdhaliwal updated this revision to Diff 266794.
pdhaliwal marked an inline comment as done.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D79400/new/

https://reviews.llvm.org/D79400

Files:
  llvm/cmake/modules/AddLLVM.cmake
  llvm/include/llvm/Support/CMakeLists.txt


Index: llvm/include/llvm/Support/CMakeLists.txt
===================================================================
--- llvm/include/llvm/Support/CMakeLists.txt
+++ llvm/include/llvm/Support/CMakeLists.txt
@@ -5,12 +5,16 @@
 
 set(generate_vcs_version_script "${LLVM_CMAKE_PATH}/GenerateVersionFromVCS.cmake")
 
-if(llvm_vc AND LLVM_APPEND_VC_REV)
+if(LLVM_APPEND_VC_REV)
   set(llvm_source_dir ${LLVM_MAIN_SRC_DIR})
+
+  if (NOT llvm_vc)
+    set(fake_version_inc "${CMAKE_CURRENT_BINARY_DIR}/__FakeVCSRevision.h")
+  endif()
 endif()
 
 # Create custom target to generate the VC revision include.
-add_custom_command(OUTPUT "${version_inc}"
+add_custom_command(OUTPUT "${version_inc}" "${fake_version_inc}"
   DEPENDS "${llvm_vc}" "${generate_vcs_version_script}"
   COMMAND ${CMAKE_COMMAND} "-DNAMES=LLVM"
                            "-DLLVM_SOURCE_DIR=${llvm_source_dir}"
@@ -22,5 +26,5 @@
   PROPERTIES GENERATED TRUE
              HEADER_FILE_ONLY TRUE)
 
-add_custom_target(llvm_vcsrevision_h DEPENDS "${version_inc}")
+add_custom_target(llvm_vcsrevision_h ALL DEPENDS "${version_inc}" "${fake_version_inc}")
 set_target_properties(llvm_vcsrevision_h PROPERTIES FOLDER "Misc")
Index: llvm/cmake/modules/AddLLVM.cmake
===================================================================
--- llvm/cmake/modules/AddLLVM.cmake
+++ llvm/cmake/modules/AddLLVM.cmake
@@ -1913,34 +1913,27 @@
   if(NOT EXISTS "${path}")
     return()
   endif()
-  if(EXISTS "${path}/.svn")
-    set(svn_files
-      "${path}/.svn/wc.db"   # SVN 1.7
-      "${path}/.svn/entries" # SVN 1.6
-    )
-    foreach(file IN LISTS svn_files)
-      if(EXISTS "${file}")
-        set(${out_var} "${file}" PARENT_SCOPE)
-        return()
-      endif()
-    endforeach()
-  else()
-    find_package(Git)
-    if(GIT_FOUND)
-      execute_process(COMMAND ${GIT_EXECUTABLE} rev-parse --git-dir
-        WORKING_DIRECTORY ${path}
-        RESULT_VARIABLE git_result
-        OUTPUT_VARIABLE git_output
-        ERROR_QUIET)
-      if(git_result EQUAL 0)
-        string(STRIP "${git_output}" git_output)
-        get_filename_component(git_dir ${git_output} ABSOLUTE BASE_DIR ${path})
-        # Some branchless cases (e.g. 'repo') may not yet have .git/logs/HEAD
-        if (NOT EXISTS "${git_dir}/logs/HEAD")
-          file(WRITE "${git_dir}/logs/HEAD" "")
+  find_package(Git)
+  if(GIT_FOUND)
+    execute_process(COMMAND ${GIT_EXECUTABLE} rev-parse --git-dir
+      WORKING_DIRECTORY ${path}
+      RESULT_VARIABLE git_result
+      OUTPUT_VARIABLE git_output
+      ERROR_QUIET)
+    if(git_result EQUAL 0)
+      string(STRIP "${git_output}" git_output)
+      get_filename_component(git_dir ${git_output} ABSOLUTE BASE_DIR ${path})
+      # Some branchless cases (e.g. 'repo') may not yet have .git/logs/HEAD
+      if (NOT EXISTS "${git_dir}/logs/HEAD")
+        execute_process(COMMAND ${CMAKE_COMMAND} -E touch HEAD
+          WORKING_DIRECTORY "${git_dir}/logs"
+          RESULT_VARIABLE touch_head_result
+          ERROR_QUIET)
+        if (NOT touch_head_result EQUAL 0)
+          return()
         endif()
-        set(${out_var} "${git_dir}/logs/HEAD" PARENT_SCOPE)
       endif()
+      set(${out_var} "${git_dir}/logs/HEAD" PARENT_SCOPE)
     endif()
   endif()
 endfunction()


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