Make use VERSION also load feature.pm

p4raw-id: //depot/perl@30446

diff --git a/MANIFEST b/MANIFEST
index b70220b..02a5fb5 100644 (file)
--- a/MANIFEST
+++ b/MANIFEST
@@ -3391,6 +3391,7 @@ t/lib/dprof/test8_t               Perl code profiler tests
 t/lib/dprof/test8_v            Perl code profiler tests
 t/lib/dprof/V.pm               Perl code profiler tests
 t/lib/feature/err              Tests for enabling/disabling err feature
+t/lib/feature/implicit         Tests for implicit loading of feature.pm
 t/lib/feature/nonesuch         Tests for enabling/disabling nonexistent feature
 t/lib/feature/say              Tests for enabling/disabling say feature
 t/lib/feature/switch           Tests for enabling/disabling switch feature

diff --git a/lib/feature.pm b/lib/feature.pm
index b8256f4..7a88b15 100644 (file)
--- a/lib/feature.pm
+++ b/lib/feature.pm
@@ -18,6 +18,8 @@ my %feature_bundle = (
 $feature_bundle{"5.10"} = $feature_bundle{"5.10.0"};
 #$feature_bundle{"5.10"} = $feature_bundle{sprintf("%vd",$^V)};
 
+$feature_bundle{"5.9.5"} = $feature_bundle{"5.10.0"};
+
 # TODO:
 # - think about versioned features (use feature switch => 2)
 
@@ -113,6 +115,33 @@ which both are equivalent to C<use feature qw(switch say err state)>.
 In the forthcoming 5.10.X perl releases, C<use feature ":5.10"> will be
 equivalent to the latest C<use feature ":5.10.X">.
 
+=head1 IMPLICIT LOADING
+
+There are two ways to load the C<feature> pragma implicitly :
+
+=over 4
+
+=item *
+
+By using the C<-E> switch on the command-line instead of C<-e>. It enables
+all available features in the main compilation unit (that is, the one-liner.)
+
+=item *
+
+By requiring explicitly a minimal Perl version number for your program, with
+the C<use VERSION> construct, and when the version is higher than or equal to
+5.9.5. That is,
+
+    use 5.9.5;
+
+will do an implicit
+
+    use feature ':5.9.5';
+
+and so on.
+
+=back
+
 =cut
 
 sub import {

diff --git a/pod/perlfunc.pod b/pod/perlfunc.pod
index b9e17b9..67e8c1e 100644 (file)
--- a/pod/perlfunc.pod
+++ b/pod/perlfunc.pod
@@ -6815,7 +6815,7 @@ except that Module I<must> be a bareword.
 
 VERSION may be either a numeric argument such as 5.006, which will be
 compared to C<$]>, or a literal of the form v5.6.1, which will be compared
-to C<$^V> (aka $PERL_VERSION.  A fatal error is produced if VERSION is
+to C<$^V> (aka $PERL_VERSION).  A fatal error is produced if VERSION is
 greater than the version of the current Perl interpreter; Perl will not
 attempt to parse the rest of the file.  Compare with L</require>, which can
 do a similar check at run time.
@@ -6833,6 +6833,10 @@ This is often useful if you need to check the current Perl version before
 C<use>ing library modules that have changed in incompatible ways from
 older versions of Perl.  (We try not to do this more than we have to.)
 
+If the specified perl version is greater than or equal to 5.9.5, C<use
+VERSION> will also load the C<feature> pragma and enable all features
+available in the requested version.  See L<feature>.
+
 The C<BEGIN> forces the C<require> and C<import> to happen at compile time.  The
 C<require> makes sure the module is loaded into memory if it hasn't been
 yet.  The C<import> is not a builtin--it's just an ordinary static method

diff --git a/pp_ctl.c b/pp_ctl.c
index 3aecb2d..c9a7f58 100644 (file)
--- a/pp_ctl.c
+++ b/pp_ctl.c
@@ -3102,7 +3102,18 @@ PP(pp_require)
                    SVfARG(vnormal(sv)), SVfARG(vnormal(PL_patchlevel)));
        }
 
-           RETPUSHYES;
+       /* If we request a version >= 5.9.5, load feature.pm with the
+        * feature bundle that corresponds to the required version.
+        * We do this only with use, not require. */
+       if (PL_compcv && vcmp(sv, sv_2mortal(upg_version(newSVnv(5.009005)))) >= 0) {
+           SV *const importsv = vnormal(sv);
+           *SvPVX_mutable(importsv) = ':';
+           ENTER;
+           Perl_load_module(aTHX_ 0, newSVpvs("feature"), NULL, importsv, NULL);
+           LEAVE;
+       }
+
+       RETPUSHYES;
     }
     name = SvPV_const(sv, len);
     if (!(name && len > 0 && *name))

diff --git a/t/lib/feature/implicit b/t/lib/feature/implicit
new file mode 100644 (file)
index 0000000..0632770
--- /dev/null
+++ b/t/lib/feature/implicit
@@ -0,0 +1,62 @@
+Check implicit loading of features with use VERSION.
+
+__END__
+# Standard feature bundle
+use feature ":5.10";
+say "Hello", "world";
+EXPECT
+Helloworld
+########
+# VERSION requirement, dotted notation
+use 5.9.5;
+say "Hello", "world";
+EXPECT
+Helloworld
+########
+# VERSION requirement, v-dotted notation
+use v5.9.5;
+say "Hello", "world";
+EXPECT
+Helloworld
+########
+# VERSION requirement, decimal notation
+use 5.009005;
+say defined $INC{"feature.pm"} ? "Helloworld" : "Good bye";
+EXPECT
+Helloworld
+########
+# VERSION requirement, doesn't load anything for < 5.9.5
+use 5.8.8;
+print "<".$INC{"feature.pm"}.">\n";
+EXPECT
+<>
+########
+# VERSION requirement, doesn't load anything with require
+require 5.9.5;
+print "<".$INC{"feature.pm"}.">\n";
+EXPECT
+<>
+########
+# VERSION requirement in eval {}
+eval {
+    use 5.9.5;
+    say "Hello", "world";
+}
+EXPECT
+Helloworld
+########
+# VERSION requirement in eval ""
+eval q{
+    use 5.9.5;
+    say "Hello", "world";
+}
+EXPECT
+Helloworld
+########
+# VERSION requirement in BEGIN
+BEGIN {
+    use 5.9.5;
+    say "Hello", "world";
+}
+EXPECT
+Helloworld