This should make things even more robust. If .git is not found, just disable all git work.

Daniel Lemire · Daniel Lemire · commit 5fc6cb15b84d · 2020-06-24T16:12:19.000-04:00
diff --git a/CMakeLists.txt b/CMakeLists.txt
@@ -16,8 +16,16 @@ include(GNUInstallDirs)
 include(cmake/simdjson-flags.cmake)
 include(cmake/simdjson-user-cmakecache.cmake)
 
+if(EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/.git)
+  set(SIMDJSON_IS_UNDER_GIT ON CACHE BOOL  "Whether cmake is under git control")
+  message( STATUS "The simdjson repository appears to be under git." )
+else()
+  set(SIMDJSON_IS_UNDER_GIT OFF CACHE BOOL  "Whether cmake is under git control")
+  message( STATUS "The simdjson repository does not appear to be under git." )
+endif()
+
 if(SIMDJSON_JUST_LIBRARY)
-  MESSAGE( STATUS "Building just the library, omitting all tests, tools and benchmarks." )
+  message( STATUS "Building just the library, omitting all tests, tools and benchmarks." )
 endif()
 
 #
diff --git a/benchmark/checkperf.cmake b/benchmark/checkperf.cmake
@@ -7,7 +7,7 @@
 
 # Clone the repository if it's not there
 find_package(Git QUIET)
-if (Git_FOUND AND (GIT_VERSION_STRING  VERSION_GREATER  "2.1.4")) # We use "-C" which requires a recent git
+if (SIMDJSON_IS_UNDER_GIT AND Git_FOUND AND (GIT_VERSION_STRING  VERSION_GREATER  "2.1.4")) # We use "-C" which requires a recent git
   message(STATUS "Git is available and it is recent. We are enabling checkperf targets.")
   # sync_git_repository(myrepo ...) creates two targets:
   # myrepo - if the repo does not exist, creates and syncs it against the origin branch
diff --git a/dependencies/CMakeLists.txt b/dependencies/CMakeLists.txt
@@ -2,7 +2,7 @@
 
 
 find_package(Git QUIET) # We want the library to build even if git is missing
-if (Git_FOUND)
+if ((Git_FOUND) AND (SIMDJSON_IS_UNDER_GIT))
   message(STATUS "Git is available.")
   # Does NOT attempt to update or otherwise modify git submodules that are already initialized.
   function(initialize_submodule DIRECTORY)
