Merge topic 'FindGit-cache-version'

76fdeb6d13 Tests: FindGit already provides the git version, re-use it
315a200f0c FindGit: Cache the GIT_EXECUTABLE version for the current run

Acked-by: Kitware Robot <kwrobot@kitware.com>
Merge-request: !5712

7 files changed, 76 insertions, 40 deletions

diff --git a/Modules/ExternalProject.cmake b/Modules/ExternalProject.cmake
index bb3684a..29cfba9 100644
--- a/Modules/ExternalProject.cmake
+++ b/Modules/ExternalProject.cmake
@@ -2633,10 +2633,13 @@ function(_ep_add_download_command name)
       --non-interactive ${svn_trust_cert_args} ${svn_user_pw_args} ${src_name})
     list(APPEND depends ${stamp_dir}/${name}-svninfo.txt)
   elseif(git_repository)
-    unset(CMAKE_MODULE_PATH) # Use CMake builtin find module
-    find_package(Git QUIET)
-    if(NOT GIT_EXECUTABLE)
-      message(FATAL_ERROR "error: could not find git for clone of ${name}")
+    # FetchContent gives us these directly, so don't try to recompute them
+    if(NOT GIT_EXECUTABLE OR NOT GIT_VERSION_STRING)
+      unset(CMAKE_MODULE_PATH) # Use CMake builtin find module
+      find_package(Git QUIET)
+      if(NOT GIT_EXECUTABLE)
+        message(FATAL_ERROR "error: could not find git for clone of ${name}")
+      endif()
     endif()
 
     _ep_get_git_submodules_recurse(git_submodules_recurse)
@@ -2954,10 +2957,13 @@ function(_ep_add_update_command name)
       --non-interactive ${svn_trust_cert_args} ${svn_user_pw_args})
     set(always 1)
   elseif(git_repository)
-    unset(CMAKE_MODULE_PATH) # Use CMake builtin find module
-    find_package(Git QUIET)
-    if(NOT GIT_EXECUTABLE)
-      message(FATAL_ERROR "error: could not find git for fetch of ${name}")
+    # FetchContent gives us these directly, so don't try to recompute them
+    if(NOT GIT_EXECUTABLE OR NOT GIT_VERSION_STRING)
+      unset(CMAKE_MODULE_PATH) # Use CMake builtin find module
+      find_package(Git QUIET)
+      if(NOT GIT_EXECUTABLE)
+        message(FATAL_ERROR "error: could not find git for fetch of ${name}")
+      endif()
     endif()
     set(work_dir ${source_dir})
     set(comment "Performing update step for '${name}'")
diff --git a/Modules/FetchContent.cmake b/Modules/FetchContent.cmake
index ba2acfc..8adef47 100644
--- a/Modules/FetchContent.cmake
+++ b/Modules/FetchContent.cmake
@@ -964,6 +964,22 @@ ExternalProject_Add_Step(${contentName}-populate copyfile
       "-DCMAKE_EP_GIT_REMOTE_UPDATE_STRATEGY=${CMAKE_EP_GIT_REMOTE_UPDATE_STRATEGY}")
   endif()
 
+  # Avoid using if(... IN_LIST ...) so we don't have to alter policy settings
+  set(__FETCHCONTENT_CACHED_INFO "")
+  list(FIND ARG_UNPARSED_ARGUMENTS GIT_REPOSITORY indexResult)
+  if(indexResult GREATER_EQUAL 0)
+    find_package(Git QUIET)
+    set(__FETCHCONTENT_CACHED_INFO
+"# Pass through things we've already detected in the main project to avoid
+# paying the cost of redetecting them again in ExternalProject_Add()
+set(GIT_EXECUTABLE [==[${GIT_EXECUTABLE}]==])
+set(GIT_VERSION_STRING [==[${GIT_VERSION_STRING}]==])
+set_property(GLOBAL PROPERTY _CMAKE_FindGit_GIT_EXECUTABLE_VERSION
+  [==[${GIT_EXECUTABLE};${GIT_VERSION_STRING}]==]
+)
+")
+  endif()
+
   # Create and build a separate CMake project to carry out the population.
   # If we've already previously done these steps, they will not cause
   # anything to be updated, so extra rebuilds of the project won't occur.
diff --git a/Modules/FetchContent/CMakeLists.cmake.in b/Modules/FetchContent/CMakeLists.cmake.in
index 45e4df0..5ebb12f 100644
--- a/Modules/FetchContent/CMakeLists.cmake.in
+++ b/Modules/FetchContent/CMakeLists.cmake.in
@@ -9,6 +9,8 @@ cmake_minimum_required(VERSION ${CMAKE_VERSION})
 
 project(${contentName}-populate NONE)
 
+@__FETCHCONTENT_CACHED_INFO@
+
 include(ExternalProject)
 ExternalProject_Add(${contentName}-populate
                     ${ARG_EXTRA}
diff --git a/Modules/FindGit.cmake b/Modules/FindGit.cmake
index f8346b6..83da707 100644
--- a/Modules/FindGit.cmake
+++ b/Modules/FindGit.cmake
@@ -77,14 +77,44 @@ unset(git_names)
 unset(_git_sourcetree_path)
 
 if(GIT_EXECUTABLE)
-  execute_process(COMMAND ${GIT_EXECUTABLE} --version
-                  OUTPUT_VARIABLE git_version
-                  ERROR_QUIET
-                  OUTPUT_STRIP_TRAILING_WHITESPACE)
-  if (git_version MATCHES "^git version [0-9]")
-    string(REPLACE "git version " "" GIT_VERSION_STRING "${git_version}")
+  # Avoid querying the version if we've already done that this run. For
+  # projects that use things like ExternalProject or FetchContent heavily,
+  # this saving can be measurable on some platforms.
+  set(__doGitVersionCheck YES)
+  if(DEFINED GIT_VERSION_STRING)
+    # This is an internal property, projects must not try to use it.
+    # We don't want this stored in the cache because it might still change
+    # between CMake runs, but it shouldn't change during a run.
+    get_property(__gitVersionProp GLOBAL
+      PROPERTY _CMAKE_FindGit_GIT_EXECUTABLE_VERSION
+    )
+    if(__gitVersionProp)
+      list(GET __gitVersionProp 0 __gitExe)
+      list(GET __gitVersionProp 1 __gitVersion)
+      if("${__gitExe}" STREQUAL "${GIT_EXECUTABLE}" AND
+         "${__gitVersion}" STREQUAL "${GIT_VERSION_STRING}")
+        set(__doGitVersionCheck NO)
+      endif()
+    endif()
+    unset(__gitVersionProp)
+    unset(__gitExe)
+    unset(__gitVersion)
+  endif()
+
+  if(__doGitVersionCheck)
+    execute_process(COMMAND ${GIT_EXECUTABLE} --version
+                    OUTPUT_VARIABLE git_version
+                    ERROR_QUIET
+                    OUTPUT_STRIP_TRAILING_WHITESPACE)
+    if (git_version MATCHES "^git version [0-9]")
+      string(REPLACE "git version " "" GIT_VERSION_STRING "${git_version}")
+      set_property(GLOBAL PROPERTY _CMAKE_FindGit_GIT_EXECUTABLE_VERSION
+        "${GIT_EXECUTABLE};${GIT_VERSION_STRING}"
+      )
+    endif()
+    unset(git_version)
   endif()
-  unset(git_version)
+  unset(__doGitVersionCheck)
 
   get_property(_findgit_role GLOBAL PROPERTY CMAKE_ROLE)
   if(_findgit_role STREQUAL "PROJECT" AND NOT TARGET Git::Git)
diff --git a/Tests/ExternalProject/CMakeLists.txt b/Tests/ExternalProject/CMakeLists.txt
index a1130dc..8fd44b4 100644
--- a/Tests/ExternalProject/CMakeLists.txt
+++ b/Tests/ExternalProject/CMakeLists.txt
@@ -298,15 +298,9 @@ set(do_git_tests 0)
 if(GIT_EXECUTABLE)
   set(do_git_tests 1)
 
-  execute_process(
-    COMMAND "${GIT_EXECUTABLE}" --version
-    OUTPUT_VARIABLE ov
-    OUTPUT_STRIP_TRAILING_WHITESPACE
-    )
-  string(REGEX REPLACE "^git version (.+)$" "\\1" git_version "${ov}")
-  message(STATUS "git_version='${git_version}'")
+  message(STATUS "GIT_VERSION_STRING='${GIT_VERSION_STRING}'")
 
-  if(git_version VERSION_LESS 1.6.5)
+  if("${GIT_VERSION_STRING}" VERSION_LESS 1.6.5)
     message(STATUS "No ExternalProject git tests with git client less than version 1.6.5")
     set(do_git_tests 0)
   endif()
diff --git a/Tests/ExternalProjectUpdate/CMakeLists.txt b/Tests/ExternalProjectUpdate/CMakeLists.txt
index fc10c67..b31a38b 100644
--- a/Tests/ExternalProjectUpdate/CMakeLists.txt
+++ b/Tests/ExternalProjectUpdate/CMakeLists.txt
@@ -51,15 +51,9 @@ set(do_git_tests 0)
 if(GIT_EXECUTABLE)
   set(do_git_tests 1)
 
-  execute_process(
-    COMMAND "${GIT_EXECUTABLE}" --version
-    OUTPUT_VARIABLE ov
-    OUTPUT_STRIP_TRAILING_WHITESPACE
-    )
-  string(REGEX REPLACE "^git version (.+)$" "\\1" git_version "${ov}")
-  message(STATUS "git_version='${git_version}'")
-
-  if(git_version VERSION_LESS 1.6.5)
+  message(STATUS "GIT_VERSION_STRING='${GIT_VERSION_STRING}'")
+
+  if("${GIT_VERSION_STRING}" VERSION_LESS 1.6.5)
     message(STATUS "No ExternalProject git tests with git client less than version 1.6.5")
     set(do_git_tests 0)
   endif()
diff --git a/Tests/ExternalProjectUpdate/ExternalProjectUpdateTest.cmake b/Tests/ExternalProjectUpdate/ExternalProjectUpdateTest.cmake
index d300e8b..aaa05d7 100644
--- a/Tests/ExternalProjectUpdate/ExternalProjectUpdateTest.cmake
+++ b/Tests/ExternalProjectUpdate/ExternalProjectUpdateTest.cmake
@@ -167,15 +167,9 @@ set(do_git_tests 0)
 if(GIT_EXECUTABLE)
   set(do_git_tests 1)
 
-  execute_process(
-    COMMAND "${GIT_EXECUTABLE}" --version
-    OUTPUT_VARIABLE ov
-    OUTPUT_STRIP_TRAILING_WHITESPACE
-    )
-  string(REGEX REPLACE "^git version (.+)$" "\\1" git_version "${ov}")
-  message(STATUS "git_version='${git_version}'")
+  message(STATUS "GIT_VERSION_STRING='${GIT_VERSION_STRING}'")
 
-  if(git_version VERSION_LESS 1.6.5)
+  if("${GIT_VERSION_STRING}" VERSION_LESS 1.6.5)
     message(STATUS "No ExternalProject git tests with git client less than version 1.6.5")
     set(do_git_tests 0)
   endif()