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Bug 5542

Summary: Clang detection in CMake build is incorrect
Product: SDL Reporter: vladius <vturbanov>
Component: *don't know*Assignee: Ryan C. Gordon <icculus>
Status: RESPONDED --- QA Contact: Sam Lantinga <slouken>
Severity: normal    
Priority: P2 CC: sezeroz
Version: HG 2.0   
Hardware: x86   
OS: Windows 10   
Attachments: Robust Clang and libc detection.
NEW Robust Clang and libc detection.

Description vladius 2021-02-09 14:41:49 UTC 
The detection mechanism uses CMAKE_COMPILER_IS_GNUCC first, but that actually hides the Clang detection that way, cause Clang is also GNU-compliant.

I would suggest swapping the two clauses like so:

# Compiler info
>if(CMAKE_C_COMPILER_ID MATCHES "Clang")
>  set(USE_CLANG TRUE)
>  set(OPT_DEF_ASM TRUE)
>elseif(CMAKE_COMPILER_IS_GNUCC)
>  set(USE_GCC TRUE)
>  set(OPT_DEF_ASM TRUE)

That would allow for a proper default LIBC value detection via:
>if(UNIX OR MINGW OR MSYS OR USE_CLANG)
>  set(OPT_DEF_LIBC ON)
>endif()

This doesn't uses the OR USE_CLANG now currently, and misses that available Clang's libc that way. This second code snippet must also be moved down, right after USE_CLANG detection to be able to work correctly.

Thank you.
Comment 1 Sam Lantinga 2021-02-09 23:05:35 UTC 
Can you attach a tested patch that implements this change?

Thanks!
Comment 2 vladius 2021-02-10 09:00:30 UTC 
Created attachment 4789 [details]
Robust Clang and libc detection.

I'm now successfully detecting the presence of the libc under Clang with the following changes:
Comment 3 vladius 2021-02-10 09:01:11 UTC 
Added a patch.
Comment 4 Ozkan Sezer 2021-02-10 12:03:50 UTC 
(In reply to vladius from comment #2)
> Created attachment 4789 [details]
> Robust Clang and libc detection.
> 
> I'm now successfully detecting the presence of the libc under Clang with the
> following changes:

This patch touches things it is not supposed to,  e.g.: all
changes after about line 400.
Comment 5 vladius 2021-02-10 13:11:47 UTC 
(In reply to Ozkan Sezer from comment #4)
> (In reply to vladius from comment #2)
> > Created attachment 4789 [details]
> > Robust Clang and libc detection.
> > 
> > I'm now successfully detecting the presence of the libc under Clang with the
> > following changes:
> 
> This patch touches things it is not supposed to,  e.g.: all
> changes after about line 400.

You're right. Seems like I've done something wrong. Not quite used to Mercurial as of now.
Attaching the correct patch now.
Comment 6 vladius 2021-02-10 13:14:13 UTC 
Created attachment 4791 [details]
NEW Robust Clang and libc detection.

Together with a patch from this issue https://bugzilla.libsdl.org/show_bug.cgi?id=5539
Clang now should compile correctly on Windows via CMake.