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Fixed bug 5366 - cmake build doesn't detect Metal on macOS

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Tom Seddon

This is as of commit 50d804ea729accf9e3a9ce83238d0a2976a17545 from https://github.com/SDL-mirror/SDL, which is HEAD as I write (apologies, not confident with Mercurial)

# Config

macOS: 10.14.6 (18G6042)
cmake --version: cmake version 3.16.20200101-g23e782c
clang --version: Apple clang version 11.0.0 (clang-1100.0.33.17)
Xcode version: Version 11.3.1 (11C504)

# Repro steps

Run the following commands in the shell.

 cd /tmp/
 git clone https://github.com/SDL-mirror/SDL
 mkdir build.SDL
 cd build.SDL
 cmake -G ../SDL/

Examine cmake output.

# Expected result

Metal is detected.

# Actual result

It appears that Metal is not detected! Note this line in the summary:

 --   RENDER_METAL           (Wanted: 0): OFF

# Fix

Change check_c_source_compiles to check_objc_source_compiles. The cmake script tries to add -ObjC to the clang command line, but, for whatever reason, this doesn't seem to work.

Change the test source to have an empty main. The "return 0;" line seems to confuse cmake somehow, causing it to crap out with an error about HAVE_FRAMEWORK_METAL being an unknown argument. (Maybe I'm just dense, but it's not obvious to me what the problem is here.)

With these two changes:

 --   RENDER_METAL           (Wanted: ON): ON

Patch attached.
This commit is contained in:
Sam Lantinga 2020-12-01 13:50:42 -08:00
parent 798b228806
commit 4b35a18d8b
1 changed files with 2 additions and 5 deletions
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7
CMakeLists.txt
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@ -20,6 +20,7 @@ include(CheckIncludeFiles)
include(CheckIncludeFile)
include(CheckSymbolExists)
include(CheckCSourceCompiles)
include(CheckOBJCSourceCompiles)
include(CheckCSourceRuns)
include(CheckCCompilerFlag)
include(CheckTypeSize)
@ -1759,9 +1760,7 @@ elseif(APPLE)
endif()
if(VIDEO_VULKAN OR VIDEO_METAL OR RENDER_METAL)
set(ORIG_CMAKE_REQUIRED_FLAGS ${CMAKE_REQUIRED_FLAGS})
set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -ObjC")
check_c_source_compiles("
check_objc_source_compiles("
#include <AvailabilityMacros.h>
#import <Metal/Metal.h>
#import <QuartzCore/CAMetalLayer.h>
@ -1771,10 +1770,8 @@ elseif(APPLE)
#endif
int main()
{
return 0;
}
" HAVE_FRAMEWORK_METAL)
set(CMAKE_REQUIRED_FLAGS ${ORIG_CMAKE_REQUIRED_FLAGS})
if(HAVE_FRAMEWORK_METAL)
set(SDL_FRAMEWORK_METAL 1)
set(SDL_FRAMEWORK_QUARTZCORE 1)