From 0af88abc907dacc1c57a4de969ee13383a151919 Mon Sep 17 00:00:00 2001
From: Sebastian Ehlert <28669218+awvwgk@users.noreply.github.com>
Date: Sat, 11 Sep 2021 16:13:05 +0200
Subject: [PATCH] Ensure module output directory is generated in configure
 stage

- subprojects using the stdlib's build interface will resolve the module
  output directory before it is created and error without this fix
---
 src/CMakeLists.txt | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index b56d75b0e..8639308cc 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -66,6 +66,12 @@ set(SRC
 add_library(${PROJECT_NAME} ${SRC})
 
 set(LIB_MOD_DIR ${CMAKE_CURRENT_BINARY_DIR}/mod_files/)
+# We need the module directory before we finish the configure stage since the
+# build interface might resolve before the module directory is generated by CMake
+if(NOT EXISTS "${LIB_MOD_DIR}")
+  make_directory("${LIB_MOD_DIR}")
+endif()
+
 set_target_properties(${PROJECT_NAME} PROPERTIES
     Fortran_MODULE_DIRECTORY ${LIB_MOD_DIR})
 target_include_directories(${PROJECT_NAME} PUBLIC