Previously we would truncate tm.tm_year for any time_t corresponding to
a year that does not fit in int. This issue was discovered because it
caused the bash-static build to fail when linking with LLD.
As reported by Rafael Espíndola:
Configure has
AC_FUNC_MKTIME
which expands to a test of mktime that fails with the freebsd
implementation. Given that, bash compiles a mktime.o file that
defines just mktime and uses localtime. That goes in a .a file
that is before libc.
The freebsd libc defines mktime in localtime.o, which also defines
localtime among other functions.
When lld sees an undefined reference to mktime from libc, it uses
the bash provided one and then tries to find a definition of
localtime. It is found on libc's localtime.o, but now we have a
duplicated error.
The reason it works with bfd is that bash doesn't use mktime
directly and the undefined reference from libc is resolved to the
libc implementation. It would also fail to link if bash itself
directly used mktime.
The bash-static configure test verifies that, for many values of t, either
localtime(t) returns NULL or mktime(localtime(t)) == t. This test failed
when localtime returned a truncated tm_year.
This was fixed in tzcode in 2004 but has persisted in our tree since
rS2708.
Reported by: Rafael Espíndola
Reviewed by: bapt
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D9534
26ab9a178c