From ceecb0ca27350a0f4e53d199a6aac0e44d586ce2 Mon Sep 17 00:00:00 2001
From: froejdh_e <erik.frojdh@psi.ch>
Date: Thu, 22 May 2025 10:20:16 +0200
Subject: [PATCH] added extra fs link and fixed execute_program warning

---
 CMakeLists.txt              |  9 ++++----
 cmake/FindClangFormat.cmake |  4 +++-
 cmake/helpers.cmake         | 46 +++++++++++++++++++++++++++++++++++++
 3 files changed, 53 insertions(+), 6 deletions(-)
 create mode 100644 cmake/helpers.cmake

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 212281f68..3b290aa5a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -21,6 +21,7 @@ if (${CMAKE_VERSION} VERSION_GREATER "3.24")
 endif()
 include(cmake/project_version.cmake)
 include(cmake/SlsAddFlag.cmake)
+include(cmake/helpers.cmake)
 
 
 
@@ -193,11 +194,9 @@ find_package(ClangFormat)
 
 set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
 
-if (NOT CMAKE_BUILD_TYPE AND NOT CMAKE_CONFIGURATION_TYPES)
-  message(STATUS "No build type selected, default to Release")
-  set(CMAKE_BUILD_TYPE "Release" CACHE STRING "Build type (default Release)" FORCE)
-endif()
-
+default_build_type("Release")
+set_std_fs_lib()
+message(STATUS "Extra linking to fs lib:${STD_FS_LIB}")
 
 #Enable LTO if available
 include(CheckIPOSupported)
diff --git a/cmake/FindClangFormat.cmake b/cmake/FindClangFormat.cmake
index 8e697896f..7b7fdd27f 100644
--- a/cmake/FindClangFormat.cmake
+++ b/cmake/FindClangFormat.cmake
@@ -25,7 +25,9 @@ mark_as_advanced(
     ClangFormat_BIN)
 
 if(ClangFormat_FOUND)
-    exec_program(${ClangFormat_BIN} ${CMAKE_CURRENT_SOURCE_DIR} ARGS --version OUTPUT_VARIABLE CLANG_VERSION_TEXT)
+    execute_process(COMMAND ${ClangFormat_BIN} --version
+                 WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
+                 OUTPUT_VARIABLE CLANG_VERSION_TEXT)
     string(REGEX MATCH "([0-9]+)\\.[0-9]+\\.[0-9]+" CLANG_VERSION ${CLANG_VERSION_TEXT})
     if((${CLANG_VERSION} GREATER "9") OR (${CLANG_VERSION} EQUAL "9"))
         # A CMake script to find all source files and setup clang-format targets for them
diff --git a/cmake/helpers.cmake b/cmake/helpers.cmake
new file mode 100644
index 000000000..2ddb9d057
--- /dev/null
+++ b/cmake/helpers.cmake
@@ -0,0 +1,46 @@
+function(default_build_type val)
+if (NOT CMAKE_BUILD_TYPE AND NOT CMAKE_CONFIGURATION_TYPES)
+  message(STATUS "No build type selected, default to Release")
+  set(CMAKE_BUILD_TYPE ${val} CACHE STRING "Build type (default ${val})" FORCE)
+endif()
+endfunction()
+
+function(set_std_fs_lib)
+# from pybind11
+# Check if we need to add -lstdc++fs or -lc++fs or nothing
+if(DEFINED CMAKE_CXX_STANDARD AND CMAKE_CXX_STANDARD LESS 17)
+  set(STD_FS_NO_LIB_NEEDED TRUE)
+elseif(MSVC)
+  set(STD_FS_NO_LIB_NEEDED TRUE)
+else()
+  file(
+    WRITE ${CMAKE_CURRENT_BINARY_DIR}/main.cpp
+    "#include <filesystem>\nint main(int argc, char ** argv) {\n  std::filesystem::path p(argv[0]);\n  return p.string().length();\n}"
+  )
+  try_compile(
+    STD_FS_NO_LIB_NEEDED ${CMAKE_CURRENT_BINARY_DIR}
+    SOURCES ${CMAKE_CURRENT_BINARY_DIR}/main.cpp
+    COMPILE_DEFINITIONS -std=c++17)
+  try_compile(
+    STD_FS_NEEDS_STDCXXFS ${CMAKE_CURRENT_BINARY_DIR}
+    SOURCES ${CMAKE_CURRENT_BINARY_DIR}/main.cpp
+    COMPILE_DEFINITIONS -std=c++17
+    LINK_LIBRARIES stdc++fs)
+  try_compile(
+    STD_FS_NEEDS_CXXFS ${CMAKE_CURRENT_BINARY_DIR}
+    SOURCES ${CMAKE_CURRENT_BINARY_DIR}/main.cpp
+    COMPILE_DEFINITIONS -std=c++17
+    LINK_LIBRARIES c++fs)
+endif()
+
+if(${STD_FS_NEEDS_STDCXXFS})
+  set(STD_FS_LIB stdc++fs PARENT_SCOPE)
+elseif(${STD_FS_NEEDS_CXXFS})
+  set(STD_FS_LIB c++fs PARENT_SCOPE)
+elseif(${STD_FS_NO_LIB_NEEDED})
+  set(STD_FS_LIB "" PARENT_SCOPE)
+else()
+  message(WARNING "Unknown C++17 compiler - not passing -lstdc++fs")
+  set(STD_FS_LIB "")
+endif()
+endfunction()
\ No newline at end of file