Re: lang/perl5 on VAX wants NaNs and infinities

On Mon, 2024-12-30 21:13:50 +0100, Jan-Benedict Glaw <[email protected]> wrote:
> On Sat, 2024-12-28 16:01:50 +0000, John Klos <[email protected]> wrote:
> > Perl is now at version 5.40.0. This new version fails to compile because it
> > wants to use NV_INF and NV_NAN.
> > 
> > What's the best way to fix this?
> 
> 
> Seems this came with
> 
> commit 5fdf6e90221900a85cd3091bd2755e41fc230d4d
> Author: Paul Evans <[email protected]>
> Date:   Mon Jan 22 22:29:39 2024 +0000
> 
>     Add builtin::inf and builtin::nan
> 
> 
> https://github.com/Perl/perl5/commit/5fdf6e90221900a85cd3091bd2755e41fc230d4d
> 
> As there is configury available for some aspects of FP NANs / INFs, I
> think that this was just an oversight and not a design decision to
> drop anything except IEEE math.  Cf. d_double_style_vax,
> d_double_has_inf and d_double_has_nan.
> 
> For now, I just started a build with reverting that patch. Let's see
> where this takes us to...

With the following patch, Perl 5.40 successfully built (though I
didn't play with the Perl interpreter as I'm by no means a Perl guy):

# cat ${LOCALPATCHES}/lang/perl5/patch-infnan
--- builtin.c~jb        2024-12-31 11:11:52.361258111 +0000
+++ builtin.c   2024-12-31 11:14:00.911496537 +0000
@@ -90,31 +90,9 @@
     XSRETURN_NO;
 }   

-XS(XS_builtin_inf);
-XS(XS_builtin_inf)
-{
-    dXSARGS;
-    if(items)
-        croak_xs_usage(cv, "");
-    EXTEND(SP, 1);
-    XSRETURN_NV(NV_INF);
-}
- 
-XS(XS_builtin_nan);
-XS(XS_builtin_nan)
-{
-    dXSARGS;
-    if(items)
-        croak_xs_usage(cv, "");
-    EXTEND(SP, 1);
-    XSRETURN_NV(NV_NAN);
-}
- 
 enum {
     BUILTIN_CONST_FALSE,
     BUILTIN_CONST_TRUE,
-    BUILTIN_CONST_INF,
-    BUILTIN_CONST_NAN,
 };
  
 static OP *ck_builtin_const(pTHX_ OP *entersubop, GV *namegv, SV *ckobj)
@@ -135,8 +113,6 @@
     switch(builtin->ckval) {
         case BUILTIN_CONST_FALSE: constval = &PL_sv_no; break;
         case BUILTIN_CONST_TRUE:  constval = &PL_sv_yes; break;
-        case BUILTIN_CONST_INF:   constval = newSVnv(NV_INF); break;
-        case BUILTIN_CONST_NAN:   constval = newSVnv(NV_NAN); break;
         default:
             DIE(aTHX_ "panic: unrecognised builtin_const value %" IVdf,
                       builtin->ckval);
@@ -546,8 +522,6 @@
     /* constants */
     { "true",  SHORTVER(5,39), &XS_builtin_true,   &ck_builtin_const, BUILTIN_CONST_TRUE,  false },
     { "false", SHORTVER(5,39), &XS_builtin_false,  &ck_builtin_const, BUILTIN_CONST_FALSE, false },
-    { "inf",        NO_BUNDLE, &XS_builtin_inf,    &ck_builtin_const, BUILTIN_CONST_INF,   true },
-    { "nan",        NO_BUNDLE, &XS_builtin_nan,    &ck_builtin_const, BUILTIN_CONST_NAN,   true },
  
     /* unary functions */
     { "is_bool",         NO_BUNDLE, &XS_builtin_func1_scalar, &ck_builtin_func1, OP_IS_BOOL,    true  },
--- lib/builtin.pm~jb   2024-12-31 11:14:13.181519277 +0000
+++ lib/builtin.pm      2024-12-31 11:15:10.461625395 +0000
@@ -18,7 +18,6 @@
  
     use builtin qw(
         true false is_bool
-        inf nan
         weaken unweaken is_weak
         blessed refaddr reftype
         created_as_string created_as_number
@@ -146,22 +145,6 @@
 This function used to be named C<isbool>. A compatibility alias is provided
 currently but will be removed in a later version.
  
-=head2 inf
- 
-    $num = inf;
- 
-This function is currently B<experimental>.
- 
-Returns the floating-point infinity value.
- 
-=head2 nan
- 
-    $num = nan;
- 
-This function is currently B<experimental>.
- 
-Returns the floating-point "Not-a-Number" value.
- 
 =head2 weaken
  
     weaken($ref);
--- lib/builtin.t~jb    2024-12-31 11:15:23.441649432 +0000
+++ lib/builtin.t       2024-12-31 11:15:59.891716916 +0000
@@ -51,25 +51,6 @@
     is(prototype(\&builtin::is_bool), '$', 'is_bool prototype');
 }
  
-# float constants
-{
-    use builtin qw( inf nan );
- 
-    ok(inf, 'inf is true');
-    ok(inf > 1E10, 'inf is bigger than 1E10');
-    ok(inf == inf, 'inf is equal to inf');
-    ok(inf == inf + 1, 'inf is equal to inf + 1');
- 
-    # Invoke the real XSUB
-    my $inf = ( \&builtin::inf )->();
-    ok($inf == $inf + 1, 'inf returned by real xsub');
- 
-    ok(nan != nan, 'NaN is not equal to NaN');
- 
-    my $nan = ( \&builtin::nan )->();
-    ok($nan != $nan, 'NaN returned by real xsub');
-}
- 
 # weakrefs
 {
     use builtin qw( is_weak weaken unweaken );





With that, we can start guarding these pieces with d_double_style_vax,
d_double_has_inf and d_double_has_nan. But maybe somebody else should
work on that? Did anybody already open a bug report upstream? I'd like
to not open multiple tickets, that won't help at all I guess...

MfG, JBG

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