From a810e30a3d560d3e6ced41c74032c54ea365a88e Mon Sep 17 00:00:00 2001
From: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Date: Sun, 16 Aug 2020 20:17:26 +0200
Subject: [PATCH] CMakeLists.txt: fix build with gcc 4.8

-Werror=incompatible-pointer-types is unconditionally used since version
2.1.4 and 137a14e106d75d1260f78acc1a19c5a936ef75b2. This will raise a
build failure when checking for threads on gcc 4.8:

/home/buildroot/autobuild/run/instance-3/output-1/host/bin/arm-none-linux-gnueabi-gcc --sysroot=/home/buildroot/autobuild/run/instance-3/output-1/host/arm-buildroot-linux-gnueabi/sysroot -DTESTKEYWORD=inline  -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os -Wall -W -Wpointer-arith -Wcast-qual -Wstrict-prototypes -Wno-unused-parameter -Wdeclaration-after-statement -Werror=implicit-function-declaration -Werror=incompatible-pointer-types -Wbad-function-cast -Wcast-align   -DNDEBUG -fPIE   -o CMakeFiles/cmTC_98946.dir/CheckIncludeFile.c.o   -c /home/buildroot/autobuild/run/instance-3/output-1/build/fluidsynth-2.1.4/CMakeFiles/CMakeTmp/CheckIncludeFile.c
cc1: error: -Werror=incompatible-pointer-types: no option -Wincompatible-pointer-types

Fixes:
 - http://autobuild.buildroot.org/results/13cbba871db56ef8657a3d13c6ac8e1b4da0d244

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
[Upstream status: https://github.com/FluidSynth/fluidsynth/pull/661]
---
 CMakeLists.txt | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 7844889..0f6c169 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -146,6 +146,7 @@ endif ( POLICY CMP0063 )
 include ( DefaultDirs )
 
 # Basic C library checks
+include ( CheckCCompilerFlag )
 include ( CheckSTDC )
 include ( CheckIncludeFile )
 include ( CheckFunctionExists )
@@ -196,7 +197,11 @@ if ( CMAKE_COMPILER_IS_GNUCC OR CMAKE_C_COMPILER_ID MATCHES "Clang" OR CMAKE_C_C
   endif ( NOT APPLE AND NOT OS2 )
 
   # define some warning flags
-  set ( CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall -W -Wpointer-arith -Wcast-qual -Wstrict-prototypes -Wno-unused-parameter -Wdeclaration-after-statement -Werror=implicit-function-declaration -Werror=incompatible-pointer-types" )
+  set ( CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall -W -Wpointer-arith -Wcast-qual -Wstrict-prototypes -Wno-unused-parameter -Wdeclaration-after-statement -Werror=implicit-function-declaration" )
+  check_c_compiler_flag ( "-Werror=incompatible-pointer-types" HAVE_INCOMPATIBLE_POINTER_TYPES )
+  if ( HAVE_INCOMPATIBLE_POINTER_TYPES )
+    set ( CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Werror=incompatible-pointer-types" )
+  endif ( HAVE_INCOMPATIBLE_POINTER_TYPES ) 
 
   # prepend to build type specific flags, to allow users to override
   set ( CMAKE_C_FLAGS_DEBUG "-g ${CMAKE_C_FLAGS_DEBUG}" )
-- 
2.27.0