I can't find any evidence of that. The gfortran 4.3 release notes strongly imply it doesn't:
"Support for backtraces on glibc-based systems via the -fbacktrace option is now implemented. On all systems, a coredump can be generated for errors in the run-time library using `-fdump-core`."
The GCC suite has a pretty clear history of not being dependent on glibc, and some searching brings up no mention of it requiring glibc, and a few mentions of people clearly building it without glibc.
'I have been attempting unsuccessfully to try the latest gfortran snapshot executables...The reason for the problem is that they require the bleeding-edge
version of GLIBC to run:'
key excerpt being: 'One problem is that the functions csqrt, csqrtf, csqrtl of libm (glibc) which are used by gcc4 are still buggy for x86_64 architectures...'
Your first link is about gfortran executables for Linux (specifically a specific snapshot build, not the source code itself), not OS X. Your second one is about glibc systems, not OS X, is over six years old, and complains simply about buggy functions in glibc -- what is it that makes you think using glibc would solve a glibc problem?
Neither of these in any way imply a general dependency on glibc. On the contrary, the second one implies you'd have more luck without it, if the issue were still extant -- which it's not, the bugs were closed out six years ago.
First: Yep, there's not much available about compiling gfortran for osx. The link does show an example of gfortran requiring glibc - which is the point you were disagreeing with.
Second: just another example (by descending order of googleableness) of the main gcc requiring glibc.
Quite possibly there is an osx (or other bsd) specific c library that can substitute for glibc, but I did not find it, and gfortran will complain without it.
'what is it that makes you think using glibc would solve a glibc problem?'
Eh? I used glibc to solve a 'missing glibc' problem. I then had other problems with glibc which I attempted to solve.
You're not understanding. The first example "requires glibc" because the binaries were linked against glibc, just like they'd be linked against OS X's libc if they'd been built for OS X.
The second example is, again, an issue of gcc being built against glibc. You can build it against any libc you want, but when built against glibc, the resulting binaries are obviously going to use glibc.
You appear to have a fundamental misunderstanding of the difference between the requirements of source code, and the requirements of the binaries built from them. The latter are not the same as the former, and will vary depending on how you built the source code.
And when I just built gfortran, it didn't complain about the lack of glibc at all. If yours was complaining, I think you must have configured something incorrectly, though it escapes me what that could be.
"Support for backtraces on glibc-based systems via the -fbacktrace option is now implemented. On all systems, a coredump can be generated for errors in the run-time library using `-fdump-core`."
The GCC suite has a pretty clear history of not being dependent on glibc, and some searching brings up no mention of it requiring glibc, and a few mentions of people clearly building it without glibc.