From 1ed6166f1f0bc9a028322ba09446d59197ce7848 Mon Sep 17 00:00:00 2001
From: Markus Blatt <markus@dr-blatt.de>
Date: Tue, 16 Mar 2021 19:33:43 +0100
Subject: [PATCH] Determine Python include directory to fix docker pypi builds

Whenever OPM_ENABLE_PYTHON is on we need to set PYTHON_INCLUDE_DIRS
as it is needed to find Python.h (shouldn't we even need to link the
library?).

This could (in theory) be done by using by issuing
find_package(Python3 REQUIRED COMPONENTS Interpreter Development)
or
find_package(PythonLibs REQUIRED).

Unfortunately, both do not work (for yet unknown reasons) when we
build pypi packages in docker (even with setting the PYTHON_EXECUTABLE
or Python3_EXECUTABLE correctly).

Hence we now use python manually to determine these.
---
 CMakeLists.txt | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 36723a6ca..e2a7bcb49 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -183,13 +183,29 @@ if (OPM_ENABLE_PYTHON)
       get_target_property(_lib_path Python3::Python IMPORTED_LOCATION)
       set(PYTHON_LIBRARY ${_lib_path})
       list(APPEND opm-common_LIBRARIES ${PYTHON_LIBRARIES})
+      set(PYTHON_INCLUDE_DIRS ${Python3_INCLUDE_DIRS})
     else()
       find_package(Python3 REQUIRED COMPONENTS Interpreter)
     endif()
     # Compatibility settings for PythonInterp and PythonLibs
-    # used e.g. in FindCwrap
+    # used e.g. in FindCwrap, pybind11
     set(PYTHON_EXECUTABLE ${Python3_EXECUTABLE})
   endif()
+  # We always need the PYTHON_INCLUDE_DIR. Unfortunately
+  # When we build pypi packages CMake will fail to determine
+  # these via the usual find_package(PythonLibs or
+  # find_package(Python3 REQUIRED COMPONENTS Interpreter Development)
+  # Hence we overwrite them here.
+  if(NOT PYTHON_INCLUDE_DIRS)
+    execute_process(COMMAND "${PYTHON_EXECUTABLE}" "-c" "from distutils import sysconfig; print(sysconfig.get_python_inc(plat_specific=True));"
+      RESULT_VARIABLE _PYTHON_DIR_SUCCESS
+      OUTPUT_VARIABLE PYTHON_INCLUDE_DIR
+      ERROR_VARIABLE _PYTHON_ERROR_VALUE)
+    if(NOT _PYTHON_DIR_SUCCESS MATCHES 0)
+      message(FATAL_ERROR "Could not determine Python include directory. Error: ${_PYTHON_ERROR_VALUE}.")
+    endif()
+    set(PYTHON_INCLUDE_DIRS ${PYTHON_INCLUDE_DIR})
+  endif()
 endif()