[MacPorts] #63467: opencv4: Add a universal variant

[MacPorts]

#63467: opencv4: Add a universal variant
--------------------------+----------------------
  Reporter:  MarkCallow   |      Owner:  stromnov
      Type:  enhancement  |     Status:  assigned
  Priority:  Normal       |  Milestone:
 Component:  ports        |    Version:
Resolution:               |   Keywords:
      Port:  opencv4      |
--------------------------+----------------------

Comment (by MarkCallow):

 I found the Portfile in my installation in
 `/opt/local/var/macports/sources/rsync.macports.org/release/tarballs/ports/graphics/opencv4`
 and changed `universal_variant   no` to `universal_variant   yes`. The
 build fails while compiling gmake.


 {{{
 :info:build /usr/bin/clang -DHAVE_CONFIG_H -I. -I../src
 -I/opt/local/include
 -isysroot/Library/Developer/CommandLineTools/SDKs/MacOSX11.sdk  -pipe -Os
 -isysroot/Library/Developer/CommandLineTools/SDKs/MacOSX11.sdk -arch arm64
 -arch x86_64 -c -o fnmatch.o fnmatch.c
 :info:build In file included from basename-lgpl.c:23:
 :info:build In file included from ./string.h:41:
 :info:build In file included from
 /Library/Developer/CommandLineTools/SDKs/MacOSX11.sdk/usr/include/string.h:152:
 :info:build
 /Library/Developer/CommandLineTools/SDKs/MacOSX11.sdk/usr/include/sys/_types/_ssize_t.h:31:33:
 error: cannot combine with previous 'type-name' declaration specifier
 :info:build typedef __darwin_ssize_t        ssize_t;
 :info:build                                 ^
 :info:build ../src/config.h:1079:17: note: expanded from macro 'ssize_t'
 :info:build #define ssize_t int
 :info:build                 ^
 :info:build In file included from fnmatch.c:34:
 :info:build In file included from ./string.h:41:
 :info:build In file included from
 /Library/Developer/CommandLineTools/SDKs/MacOSX11.sdk/usr/include/string.h:152:
 :info:build
 /Library/Developer/CommandLineTools/SDKs/MacOSX11.sdk/usr/include/sys/_types/_ssize_t.h:31:33:
 error: cannot combine with previous 'type-name' declaration specifier
 :info:build typedef __darwin_ssize_t        ssize_t;
 :info:build                                 ^
 :info:build ../src/config.h:1079:17: note: expanded from macro 'ssize_t'
 :info:build #define ssize_t int
 :info:build                 ^
 :info:build 1 error generated.

 }}}


 I am surprised because I expect gmake is a dependency of quite a few
 ports. The issue most likely is that there is a config macro controlling
 some cpu-specific behaviour but since both architectures are being
 compiled in a single call to clang only one set of macros can be defined.
 For universal builds to work cpu-specific behaviour needs to be controlled
 using compiler pre-defined macros.

 It looks like I will have to abandon plans for a universal build and make
 2 cpu-specific builds instead.

-- 
Ticket URL: <https://trac.macports.org/ticket/63467#comment:4>
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