AC_COMPILE_IFELSE only tries to compile a `*.c' to a `*.o'. The
Solaris Studio 12.1 through 12.5 compilers see the
`-fvisibility=hidden' flag, but ignore it with a warning of:
cc: Warning: Option -fvisibility=hidden passed to ld,
if ld is invoked, ignored otherwise
AC_LINK_IFELSE does the compile and then tries to link the result,
at which point the Solaris linker will issue an error:
ld: fatal: option '-fvisibility=hidden' is incompatible with
building a dynamic executable
If we don't use AC_LINK_IFELSE to catch the error, then configure
will fail further tests which attempt to link, such as those testing
dependencies like `libbz2'.
Also, don't try adding `-fvisibility' if we have already added
`-xldscope', just use one of them, since Sun Studio 12 and earlier
compilers only issue a warning, and don't try passing through to the
linker to generate an error, so AC_LINK_IFELSE doesn't catch them.
Tested on Solaris 11.4 beta with compiler versions:
Sun Studio 8 (Sun C 5.5)
Sun Studio 10 (Sun C 5.7)
Sun Studio 11 (Sun C 5.8)
Sun Studio 12 (Sun C 5.9)
Sun Studio 12.1 (Sun C 5.10)
Oracle Solaris Studio 12.2 (Sun C 5.11)
Oracle Solaris Studio 12.3 (Sun C 5.12)
Oracle Solaris Studio 12.4 (Sun C 5.13)
Oracle Developer Studio 12.5 (Sun C 5.14)
Oracle Developer Studio 12.6 (Sun C 5.15)
gcc 5.5.0
gcc 7.3.0
and verified the libfreetype.so.6 generated by each of those
compilers exported the same set of symbols.
* builds/unix/configure.raw: Implement it.
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