meson: other ports can't build universal

[ryandesign (Ryan Carsten Schmidt)]

babl @0.1.82_0 can't build with the universal variant on macOS High Sierra:

:info:build ../babl-0.1.82/babl/babl-extension.c:201:3: error: use of undeclared identifier 'HLIB'
:info:build   HLIB  dl_handle = NULL;
:info:build   ^
:info:build ../babl-0.1.82/babl/babl-extension.c:206:3: error: use of undeclared identifier 'dl_handle'
:info:build   dl_handle = dlopen (path, RTLD_NOW);
:info:build   ^
:info:build ../babl-0.1.82/babl/babl-extension.c:206:15: error: implicit declaration of function 'dlopen' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
:info:build   dl_handle = dlopen (path, RTLD_NOW);
:info:build               ^
:info:build ../babl-0.1.82/babl/babl-extension.c:207:8: error: use of undeclared identifier 'dl_handle'
:info:build   if (!dl_handle)
:info:build        ^
:info:build ../babl-0.1.82/babl/babl-extension.c:209:43: error: implicit declaration of function 'dlerror' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
:info:build       babl_log ("dlopen() failed:\n\t%s", dlerror ());
:info:build                                           ^
:info:build ../babl-0.1.82/babl/babl-extension.c:212:34: error: implicit declaration of function 'dlsym' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
:info:build   init = (BablExtensionInitFunc) dlsym (dl_handle, "init");
:info:build                                  ^
:info:build ../babl-0.1.82/babl/babl-extension.c:212:41: error: use of undeclared identifier 'dl_handle'
:info:build   init = (BablExtensionInitFunc) dlsym (dl_handle, "init");
:info:build                                         ^
:info:build ../babl-0.1.82/babl/babl-extension.c:216:7: error: implicit declaration of function 'dlclose' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
:info:build       dlclose (dl_handle);
:info:build       ^
:info:build ../babl-0.1.82/babl/babl-extension.c:216:16: error: use of undeclared identifier 'dl_handle'
:info:build       dlclose (dl_handle);
:info:build                ^
:info:build ../babl-0.1.82/babl/babl-extension.c:220:47: error: use of undeclared identifier 'dl_handle'
:info:build   destroy = (BablExtensionDestroyFunc) dlsym (dl_handle, "destroy");
:info:build                                               ^
:info:build ../babl-0.1.82/babl/babl-extension.c:222:28: error: use of undeclared identifier 'dl_handle'
:info:build                            dl_handle,
:info:build                            ^
:info:build ../babl-0.1.82/babl/babl-extension.c:229:16: error: use of undeclared identifier 'dl_handle'
:info:build       dlclose (dl_handle);
:info:build                ^
:info:build 12 errors generated.

I believe the reason why these things cannot be found is that the right header has not been included because meson incorrectly determined that the header did not exist:

:info:configure Has header "stdatomic.h" : NO 
:info:configure Has header "dlfcn.h" : NO 

The reason why meson didn't detect these headers is that it incorrectly used -arch flags when doing so: from meson-log.txt:

Running compile:
Working directory:  /opt/local/var/macports/build/_Users_rschmidt_macports_macports-ports-ryandesign-fork_graphics_babl/babl/work/build/meson-private/tmpoi5rwtan
Command line:  ccache /usr/bin/clang -I/opt/local/include /opt/local/var/macports/build/_Users_rschmidt_macports_macports-ports-ryandesign-fork_graphics_babl/babl/work/build/meson-private/tmpoi5rwtan/testfile.c -pipe -E -P -Os -Werror=implicit-function-declaration -arch x86_64 -arch i386 -P -O0 

Code:
 
        #ifdef __has_include
         #if !__has_include("dlfcn.h")
          #error "Header 'dlfcn.h' could not be found"
         #endif
        #else
         #include <dlfcn.h>
        #endif
Compiler stdout:
 
Compiler stderr:
 clang: error: cannot use 'cpp-output' output with multiple -arch options

Has header "dlfcn.h" : NO 

I believe it is a defect in meson that it is using -arch flags for these tests. autoconf does not have this defect.

When not building universal, the configure output is:

Has header "stdatomic.h" : YES
Has header "dlfcn.h" : YES

and the build succeeds.

P.S: @SoapZA please log in to MacPorts Trac so that your GitHub handle is available for auto-completion in the assignment and Cc fields.

[kencu (Ken)]

Known issue with meson, may or may not ever be fixed upstream. They are aware, Jeremy opened an issue months ago about this.

For now, you’re in luck that I at least made the muniversal PG work correctly.

That may be all we ever get for this, but time will tell.

[ryandesign (Ryan Carsten Schmidt)]

So the meson portgroup should include the muniversal portgroup so that all meson-using ports are fixed? or what?

[kencu (Ken)]

I am not at this point able to say if every port that builds with meson cannot build universal without the muniversal PG. It might be so, but I haven't verified that.

Jeremy's upstream issue <​https://github.com/mesonbuild/meson/issues/8206>.