From 9c5478562eba4bed32577a1dd7ce02b3bb7f6b4e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=B6rg=20Krause?= <joerg.krause@embedded.rocks>
Date: Thu, 29 Oct 2015 09:19:41 +0100
Subject: [PATCH 1/1] Add option JSONCPP_WITH_STRICT_ISO
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'-pedantic' issues all warnings demanded by strict ISO C/C++; rejecting
extensions that do not follow ISO C/C++. Without this option, certain GNU
extensions and traditional C/C++ features are supported as well.

With this option enabled building jsoncpp fails with the musl toolchain on
x86 because of an incompatible posix_memalign declaration [1]. Without
'-pedantic' there is no error anymore and jsoncpp builds fine.

Add an option JSONCPP_WITH_STRICT_ISO to disable compilation with '-pedantic'
with GCC. If jsoncpp is build with the JSONCPP_WITH_WARNING_AS_ERROR option
'-pedantic-errors' is used instead.

[1] https://gcc.gnu.org/ml/gcc-patches/2015-05/msg01425.html

Backported from: 48bfe910622d79507983fc36254ca9f3ca63acb6

Signed-off-by: Jörg Krause <joerg.krause@embedded.rocks>
---
 CMakeLists.txt | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 62bf203..60ecb6f 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -7,6 +7,7 @@ ENABLE_TESTING()
 OPTION(JSONCPP_WITH_TESTS "Compile and (for jsoncpp_check) run JsonCpp test executables" ON)
 OPTION(JSONCPP_WITH_POST_BUILD_UNITTEST "Automatically run unit-tests as a post build step" ON)
 OPTION(JSONCPP_WITH_WARNING_AS_ERROR "Force compilation to fail if a warning occurs" OFF)
+OPTION(JSONCPP_WITH_STRICT_ISO "Issue all the warnings demanded by strict ISO C and ISO C++" ON)
 OPTION(JSONCPP_WITH_PKGCONFIG_SUPPORT "Generate and install .pc files" ON)
 OPTION(JSONCPP_WITH_CMAKE_PACKAGE "Generate and install cmake package files" OFF)
 OPTION(BUILD_SHARED_LIBS "Build jsoncpp_lib as a shared library." OFF)
@@ -83,6 +84,9 @@ macro(UseCompilationWarningAsError)
         # Only enabled in debug because some old versions of VS STL generate
         # warnings when compiled in release configuration.
 		set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} /WX ")
+  elseif (CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
+    if (JSONCPP_WITH_STRICT_ISO)
+      set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -pedantic-errors")
 	endif( MSVC )
 endmacro()
 
@@ -100,8 +104,12 @@ if (CMAKE_CXX_COMPILER_ID MATCHES "Clang")
   set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11 -Wall -Wconversion -Wshadow -Wno-sign-conversion")
 elseif ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU")
   # using GCC
-  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11 -Wall -Wconversion -Wshadow -Wextra -pedantic")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11 -Wall -Wconversion -Wshadow -Wextra")
   # not yet ready for -Wsign-conversion
+
+  if (JSONCPP_WITH_STRICT_ISO AND NOT JSONCPP_WITH_WARNING_AS_ERROR)
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -pedantic")
+  endif ()
 endif()
 
 IF(JSONCPP_WITH_WARNING_AS_ERROR)
-- 
2.6.2