[Config] CMake: Shallow clone when using the git-fetch mechanism (#5889)

* fetch shallow clone on repo

* do not use shallow feature if the GIT_TAG is hash to a commit

---------

Co-authored-by: Hugo <hugo.talbot@sofa-framework.org>
Co-authored-by: Paul Baksic <30337881+bakpaul@users.noreply.github.com>

Author: 3 people

Sofa/framework/Config/cmake/SofaMacrosConfigure.cmake

@@ -204,6 +204,12 @@ macro(sofa_fetch_dependency name)
             file(MAKE_DIRECTORY "${fetched_dir}-temp/")
         endif()
 
+        set(GIT_SHALLOW_VALUE TRUE)
+        # GIT_SHALLOW does work if GIT_TAG is a commit SHA hash
+        __is_git_tag_commit_hash(${upper_name}_GIT_TAG IS_GIT_TAG_COMMIT_HASH)
+        if(IS_GIT_TAG_COMMIT_HASH)
+            set(GIT_SHALLOW_VALUE FALSE)
+        endif()
 
         file(WRITE ${fetched_dir}-temp/CMakeLists.txt "
         cmake_minimum_required(VERSION 3.22)
@@ -219,6 +225,7 @@ macro(sofa_fetch_dependency name)
             INSTALL_COMMAND \"\"
             TEST_COMMAND \"\"
             GIT_CONFIG \"remote.origin.fetch=+refs/pull/*:refs/remotes/origin/pr/*\"
+            GIT_SHALLOW ${GIT_SHALLOW_VALUE}
             )"
         )
 

Sofa/framework/Config/cmake/SofaMacrosUtils.cmake

@@ -52,3 +52,18 @@ function(sofa_get_all_targets var)
     set(${var} ${targets} PARENT_SCOPE)
 endfunction()
 
+# guess if the git tag is a commit hash or an actual tag or a branch nane.
+# heavily inspired by https://github.com/cpm-cmake/CPM.cmake/pull/130/changes#diff-6fcfee7f313f15253f88285a499e62cb58746d47ff2cfec173f1f4cd29feb44d
+function(__is_git_tag_commit_hash GIT_TAG RESULT)
+  string(LENGTH ${GIT_TAG} length)
+  # full hash has 40 characters, and short hash has at least 7 characters.
+  if (length LESS 7 OR length GREATER 40)
+    SET(${RESULT} 0 PARENT_SCOPE)
+  else()
+    if (${GIT_TAG} MATCHES "^[a-fA-F0-9]+$")
+      SET(${RESULT} 1 PARENT_SCOPE)
+    else()
+      SET(${RESULT} 0 PARENT_SCOPE)
+    endif()
+  endif()
+endfunction()