POSIX: delete the L_tmpnam and L_tmpname symbols

The history here is relatively complicated.

The L_tmpname symbol is neither specified by POSIX or defined by traditional
Unix system; it's simply a typo for L_tmpnam, first introduced in Perl 5.0.

Commit 33f01dd10fdacfa5ccb83c4f933cacb0f65b707e (part of Perl 5.6) added
support for L_tmpnam, treating L_tmpname as a back-compat synonym. However,
no version of Perl has ever made L_tmpnam exportable, even at explicit
request; using that symbol has always required using its fully-qualified
POSIX::L_tmpnam name.

During the 5.8 development cycle, an apparently-unintended consequence of
various improvements to the way that POSIX.pm generates and exports constants
meant that L_tmpname stopped working. It continued to be exportable, but
trying to use the constant yielded an exception saying "Your vendor has not
defined POSIX macro L_tmpname". (This isn't exactly incorrect, of course: no
vendor defines the macro L_tmpname!)

At this point, therefore, there seems little benefit in trying to resurrect
support for the L_tmpname typo: it's impossible for any program running on
5.8.0 or later to have successfully used it.

There's perhaps an argument for making L_tmpnam exportable at this point,
since it does work when called by its full-qualified name. One option would
be to add it to @EXPORT_OK; but that is explicitly counselled against by the
POSIX.pm comments summarising the policy on symbol exports, which recommend
adding a new export tag instead. In this case, the obvious tag to use is
:stdio_h (which already exists), since the C-level symbol is provided by the
<stdio.h> header.

However, that doesn't seem worth it to me. The only possible use of L_tmpnam
is to create a buffer of a size suitable for passing to the tmpnam() C
function (which is presumably why nobody's noticed in the last fifteen years
that the symbol isn't actually exported). Furthermore, the POSIX.pm wrapper
for tmpnam() itself was deleted by 19fc2965b60669d7bc25548edb32e3cdd86a68de,
a few days ago, so merely deleting this additional symbol seems correct.

2 files changed, 3 insertions, 2 deletions

diff --git a/ext/POSIX/t/export.t b/ext/POSIX/t/export.t
index f82a5919fe..5f71b32bb7 100644
--- a/ext/POSIX/t/export.t
+++ b/ext/POSIX/t/export.t
@@ -49,7 +49,7 @@ my %expect = (
             LC_CTYPE LC_MESSAGES LC_MONETARY LC_NUMERIC LC_TIME LDBL_DIG
             LDBL_EPSILON LDBL_MANT_DIG LDBL_MAX LDBL_MAX_10_EXP
             LDBL_MAX_EXP LDBL_MIN LDBL_MIN_10_EXP LDBL_MIN_EXP LINK_MAX
-            LONG_MAX LONG_MIN L_ctermid L_cuserid L_tmpname MAX_CANON
+            LONG_MAX LONG_MIN L_ctermid L_cuserid MAX_CANON
             MAX_INPUT MB_CUR_MAX MB_LEN_MAX NAME_MAX NCCS NDEBUG
             NGROUPS_MAX NOFLSH NULL OPEN_MAX OPOST O_ACCMODE O_APPEND
             O_CREAT O_EXCL O_NOCTTY O_NONBLOCK O_RDONLY O_RDWR O_TRUNC
@@ -148,7 +148,7 @@ my %expect = (
             localtime log mkdir nice open opendir pipe printf rand
             read readdir rename rewinddir rmdir sin sleep sprintf sqrt
             srand stat system time times umask unlink utime wait
-            waitpid write
+            waitpid write L_tmpnam
         ),
         # this stuff was added in 5.21
         # (though an oversight meant that lround wasn't listed here
diff --git a/ext/POSIX/t/unimplemented.t b/ext/POSIX/t/unimplemented.t
index 9a03a75265..6ee85f683d 100644
--- a/ext/POSIX/t/unimplemented.t
+++ b/ext/POSIX/t/unimplemented.t
@@ -88,6 +88,7 @@ foreach ([atexit => 'C-specific: use END {} instead'],
 	 [vfprintf => 'C-specific, stopped'],
 	 [vprintf => 'C-specific, stopped'],
 	 [vsprintf => 'C-specific, stopped'],
+	 [L_tmpnam => 'C-specific, stopped'],
 	) {
     my ($func, $action) = @$_;
     my $expect = ref $action