From 8c0a2daa1320a5a5bdc470a6c3a551822f67748c Mon Sep 17 00:00:00 2001
From: pac <sepental.patrik@gmail.com>
Date: Fri, 20 Dec 2019 04:48:14 +0100
Subject: [PATCH] Fixes to cmake for MSVC build

---
 CMakeLists.txt | 20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 64116d6..83c1b4c 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -24,12 +24,26 @@ endif()
 
 add_library(json11 json11.cpp)
 target_include_directories(json11 PUBLIC ${CMAKE_CURRENT_SOURCE_DIR})
-target_compile_options(json11
-  PRIVATE -fPIC -fno-rtti -fno-exceptions -Wall)
+if (NOT MSVC)
+  target_compile_options(json11
+    PRIVATE -fPIC -fno-rtti -fno-exceptions -Wall)
+endif()
 
 # Set warning flags, which may vary per platform
 include(CheckCXXCompilerFlag)
-set(_possible_warnings_flags /W4 /WX -Wextra -Werror)
+set(_possible_warnings_flags /W4 /WX)
+#
+# Add Wextra & Werror compiler flags only if not building with Microsoft compiler
+#
+# NOTE:
+#   check_cxx_compiler_flag() for these flags evaluates to positive result
+#   but during build, cl.exe fails with following error
+#   cl : Command line error D8021: invalid numeric argument '/Wextra'
+#
+if (NOT MSVC)
+  set(_possible_warnings_flags ${_possible_warnings_flags} -Wextra -Werror)
+endif()
+
 foreach(_warning_flag ${_possible_warnings_flags})
   unset(_flag_supported)
   CHECK_CXX_COMPILER_FLAG(${_warning_flag} _flag_supported)