Absorb -D_USE_32BIT_TIME_T switch from Perl, if relevant.

Commit 3c163a7fc's original choice to ignore all #define symbols whose
names begin with underscore turns out to be too simplistic.  On Windows,
some Perl installations are built with -D_USE_32BIT_TIME_T, and we must
absorb that or we get the wrong result for sizeof(PerlInterpreter).

This effectively re-reverts commit ef58b87df, which injected that symbol
in a hacky way, making it apply to all of Postgres not just PL/Perl.
More significantly, it did so on *all* 32-bit Windows builds, even when
the Perl build to be used did not select this option; so that it fails
to work properly with some newer Perl builds.

By making this change, we would be introducing an ABI break in 32-bit
Windows builds; but fortunately we have not used type time_t in any
exported Postgres APIs in a long time.  So it should be OK, both for
PL/Perl itself and for third-party extensions, if an extension library
is built with a different _USE_32BIT_TIME_T setting than the core code.

Patch by me, based on research by Ashutosh Sharma and Robert Haas.
Back-patch to all supported branches, as commit 3c163a7fc was.

Discussion: https://postgr.es/m/CANFyU97OVQ3+Mzfmt3MhuUm5NwPU=-FtbNH5Eb7nZL9ua8=rcA@mail.gmail.com

3 files changed, 7 insertions, 17 deletions

diff --git a/src/tools/msvc/MSBuildProject.pm b/src/tools/msvc/MSBuildProject.pm
index e1c8d81549b..ec7de131156 100644
--- a/src/tools/msvc/MSBuildProject.pm
+++ b/src/tools/msvc/MSBuildProject.pm
@@ -63,21 +63,16 @@ EOF
   </PropertyGroup>
 EOF
 
-	# We have to use this flag on 32 bit targets because the 32bit perls
-	# are built with it and sometimes crash if we don't.
-	my $use_32bit_time_t =
-	  $self->{platform} eq 'Win32' ? '_USE_32BIT_TIME_T;' : '';
-
 	$self->WriteItemDefinitionGroup(
 		$f, 'Debug',
-		{   defs    => "_DEBUG;DEBUG=1;$use_32bit_time_t",
+		{   defs    => "_DEBUG;DEBUG=1",
 			opt     => 'Disabled',
 			strpool => 'false',
 			runtime => 'MultiThreadedDebugDLL' });
 	$self->WriteItemDefinitionGroup(
 		$f,
 		'Release',
-		{   defs    => "$use_32bit_time_t",
+		{   defs    => "",
 			opt     => 'Full',
 			strpool => 'true',
 			runtime => 'MultiThreadedDLL' });
diff --git a/src/tools/msvc/Mkvcbuild.pm b/src/tools/msvc/Mkvcbuild.pm
index d7b64a4046e..109b3ee5633 100644
--- a/src/tools/msvc/Mkvcbuild.pm
+++ b/src/tools/msvc/Mkvcbuild.pm
@@ -145,14 +145,15 @@ sub mkvcbuild
 		my @perl_embed_ccflags;
 		foreach my $f (split(" ",$Config{ccflags}))
 		{
-			if ($f =~ /^-D[^_]/)
+			if ($f =~ /^-D[^_]/ ||
+			    $f =~ /^-D_USE_32BIT_TIME_T/)
 			{
 				$f =~ s/\-D//;
 				push(@perl_embed_ccflags, $f);
 			}
 		}
 
-		# XXX this probably is redundant now?
+		# Also, a hack to prevent duplicate definitions of uid_t/gid_t
 		push(@perl_embed_ccflags, 'PLPERL_HAVE_UID_GID');
 
 		foreach my $f (@perl_embed_ccflags)
diff --git a/src/tools/msvc/VCBuildProject.pm b/src/tools/msvc/VCBuildProject.pm
index 335a1f016d5..f4059872ac6 100644
--- a/src/tools/msvc/VCBuildProject.pm
+++ b/src/tools/msvc/VCBuildProject.pm
@@ -33,15 +33,9 @@ sub WriteHeader
  <Configurations>
 EOF
 
-	# We have to use this flag on 32 bit targets because the 32bit perls
-	# are built with it and sometimes crash if we don't.
-	my $use_32bit_time_t =
-	  $self->{platform} eq 'Win32' ? '_USE_32BIT_TIME_T;' : '';
-
-
 	$self->WriteConfiguration(
 		$f, 'Debug',
-		{   defs     => "_DEBUG;DEBUG=1;$use_32bit_time_t",
+		{   defs     => "_DEBUG;DEBUG=1",
 			wholeopt => 0,
 			opt      => 0,
 			strpool  => 'false',
@@ -49,7 +43,7 @@ EOF
 	$self->WriteConfiguration(
 		$f,
 		'Release',
-		{   defs     => "$use_32bit_time_t",
+		{   defs     => "",
 			wholeopt => 0,
 			opt      => 3,
 			strpool  => 'true',