libsdl2: fails to build due to unknown builtin '__builtin_bswap16'

[mrkapqa]

hello,

on mountain lion building of mpv fails with error here

--->  Attempting to fetch SDL2-2.0.16.tar.gz from http://distfiles.macports.org/libsdl2
--->  Verifying checksums for libsdl2                                                
--->  Extracting libsdl2
--->  Configuring libsdl2
Warning: Configuration logfiles contain indications of -Wimplicit-function-declaration; check that features were not accidentally disabled:
  _m_prefetch: found in SDL2-2.0.16/config.log
--->  Building libsdl2
Error: Failed to build libsdl2: command execution failed 
Error: See /opt/local/var/macports/logs/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_devel_libsdl2/libsdl2/main.log for details.
Error: Follow https://guide.macports.org/#project.tickets if you believe there is a bug.
Error: Processing of port mpv failed

[kencu (Ken)]

error: use of unknown builtin '__builtin_bswap16'

it built on 10.6.8, so forcing a newer clang on the several failing systems should do it.

[mrkapqa]

çkencu, please let me know which is the proper route for installing clang, as i have installed only xcode 4.6.3 for mountain lion 10.8; xcode 5.0 and xcode 5.0.2 is no longer downloadable it seems on the applesite (gives me "forbidden") and xcode 5.1.1 requires 10.8.4.

[kencu (Ken)]

according to <​https://packages.macports.org/libsdl2/> everything from 10.7 thru 10.11 failed.

so we need to blacklist the clangs up to what is in 10.11, and that should do it.

Josh is around. Probably already working on it.

[kencu (Ken)]

if you do this, it should work until he fixes it:

sudo port clean libsdl2
sudo port install clang-9.0
sudo port install libsdl2 configure.compiler=macports-clang-9.0

[jmroot (Joshua Root)]

​https://github.com/libsdl-org/SDL/pull/4639

[jmroot (Joshua Root)]

In 4d5a9a89c4246c19c1dde2530f167ec9c028fa0c/macports-ports (master):

libsdl2: fix build on older systems

Closes: #63360