[MacPorts] #64412: mariadb-10.6/7 fails to build on Mojave 10.14.6

[MacPorts]

#64412: mariadb-10.6/7 fails to build on Mojave 10.14.6
----------------------------------------+----------------------------
  Reporter:  ArtKoKo                    |      Owner:  michaelld
      Type:  defect                     |     Status:  assigned
  Priority:  Normal                     |  Milestone:
 Component:  ports                      |    Version:  2.7.1
Resolution:                             |   Keywords:  mariadb mojave
      Port:  mariadb-10.6 mariadb-10.7  |
----------------------------------------+----------------------------

Comment (by outis):

 The code generating the error (in 'server-
 mariadb-10.7.1/storage/innobase/include/fil0fil.h') is:

 {{{
 #if defined __clang_major__ && __clang_major__ < 10
   /* Only clang-10 introduced support for asm goto */
   return n_pending.fetch_or(STOPPING, std::memory_order_relaxed) &
 STOPPING;
 #elif defined __GNUC__ && (defined __i386__ || defined __x86_64__)
   static_assert(STOPPING == 1U << 31, "compatibility");
   __asm__ goto("lock btsl $31, %0\t\njnc %l1" : : "m" (n_pending)
                : "cc", "memory" : not_stopped);
   return true;
 not_stopped:
   return false;
 #elif defined _MSC_VER && (defined _M_IX86 || defined _M_IX64)
 }}}

 On my own system (which is experiencing this issue), the version info for
 clang++ used in the build is:
 {{{
 Apple LLVM version 10.0.1 (clang-1001.0.46.4)
 Target: x86_64-apple-darwin18.7.0
 Thread model: posix
 InstalledDir:
 /Applications/Devel/Mac/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin
 }}}

 It appears that even though the MariaDB code contends that clang++ 10.+
 supports asm goto, the Apple version (a least) does not. LLVM's related
 [https://bugs.llvm.org/show_bug.cgi?id=9295 bug report] and
 [https://releases.llvm.org/9.0.0/tools/clang/docs/ReleaseNotes.html#c
 -language-changes-in-clang clang 9's release notes] both say initial
 support was created for version 9, which supports MariaDB's statement (I
 couldn't find anything in the v10.0.0 documents that confirmed whether
 full support was available). This could be considered a MariaDB bug, but
 only if they offer support for MacOS. Whether or not it is, a fix in
 macports would be quite useful (and could always be pushed upstream).

-- 
Ticket URL: <https://trac.macports.org/ticket/64412#comment:1>
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