From 630ef989510a25e31cdfc516344ed87eaf7ec122 Mon Sep 17 00:00:00 2001
From: Leonid Yuriev <leo@yuriev.ru>
Date: Sun, 7 Nov 2021 02:15:03 +0300
Subject: [PATCH] mdbx-cmake: allow to define `CMAKE_CXX_STANDARD` by the
 environment variable.

---
 CMakeLists.txt | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 49429eb3..cf57d4bb 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -335,6 +335,9 @@ list(FIND CMAKE_CXX_COMPILE_FEATURES cxx_std_14 HAS_CXX14)
 list(FIND CMAKE_CXX_COMPILE_FEATURES cxx_std_17 HAS_CXX17)
 list(FIND CMAKE_CXX_COMPILE_FEATURES cxx_std_20 HAS_CXX20)
 if(NOT DEFINED MDBX_CXX_STANDARD)
+  if(DEFINED ENV{CMAKE_CXX_STANDARD})
+    set(CMAKE_CXX_STANDARD $ENV{CMAKE_CXX_STANDARD})
+  endif()
   if(DEFINED CMAKE_CXX_STANDARD)
     set(MDBX_CXX_STANDARD ${CMAKE_CXX_STANDARD})
   elseif(NOT HAS_CXX20 LESS 0