From a1e6fcbfc5493a4559c2581ef077bd4666dfcd39 Mon Sep 17 00:00:00 2001
From: q-posev <posenitskiy@irsamc.ups-tlse.fr>
Date: Wed, 17 Nov 2021 10:07:19 +0100
Subject: [PATCH] add detection of emacs and min required version of Python3

---
 CMakeLists.txt | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index b688d92..073d0f4 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -18,9 +18,19 @@ option(TREXIO_DEVEL "TREXIO developer mode (for code generation)." OFF)
 
 if(EXISTS ".git/config")
   set(TREXIO_DEVEL ON)
-  find_package(Python3)
+  find_package(Python3 REQUIRED)
   if(Python3_FOUND)
-    message(STATUS "Python3 version :: ${Python3_VERSION}")
+    if(Python3_VERSION_MINOR LESS 6)
+      message(FATAL_ERROR "Required Python3 version :: >= 3.6; Found :: ${Python3_VERSION}")
+    else()
+      message(STATUS "Python3 version :: ${Python3_VERSION}")
+    endif()
+  endif()
+  find_program(EMACS NAMES emacs REQUIRED)
+  if(NOT EMACS-NOTFOUND)
+    message(STATUS "EMACS detected :: ${EMACS}")
+  else()
+    message(FATAL_ERROR "EMACS not found. It is required to produce TREXIO source code from org-mode files.")
   endif()
 endif()