[MacPorts] #60698: mod_gnutls: error: use of unknown builtin '__builtin_add_overflow'

[MacPorts]

#60698: mod_gnutls: error: use of unknown builtin '__builtin_add_overflow'
-------------------------------------------------+-------------------------
 Reporter:  ryandesign                           |      Owner:  Schamschula
     Type:  defect                               |     Status:  assigned
 Priority:  Normal                               |  Milestone:
Component:  ports                                |    Version:  2.6.2
 Keywords:  yosemite mavericks mountainlion      |       Port:  mod_gnutls
  lion                                           |
-------------------------------------------------+-------------------------
 [https://build.macports.org/builders/ports-10.10_x86_64-builder/builds/117391/steps
 /install-port/logs/stdio mod_gnutls doesn't build] on 10.7 thru 10.10
 inclusive:

 {{{
 gnutls_sni.c:48:9: warning: implicit declaration of function 'bswap_16' is
 invalid in C99 [-Wimplicit-function-declaration]
     u = bswap_16(u);
         ^
 gnutls_io.c:624:16: error: use of unknown builtin '__builtin_add_overflow'
 [-Wimplicit-function-declaration]
             && __builtin_add_overflow(readbytes, 0, &len))
                ^
 gnutls_ocsp.c:476:9: error: use of unknown builtin
 '__builtin_add_overflow' [-Wimplicit-function-declaration]
     if (__builtin_add_overflow(fplen, 0, &fingerprint.size))
         ^
 1 error generated.
 make[1]: *** [mod_gnutls_la-gnutls_io.lo] Error 1
 }}}

 It
 [https://build.macports.org/builders/ports-10.6_x86_64-builder/builds/25738/steps
 /install-port/logs/stdio does build on 10.6] using clang 9 so adding
 `compiler.blacklist-append {clang < 800}` could be one solution. However
 if the code can be fixed to work with old compilers that would be
 preferable.

-- 
Ticket URL: <https://trac.macports.org/ticket/60698>
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