Merge ea76afd into 24eef90

MANIFEST

@@ -5640,6 +5640,7 @@ t/lib/feature/multidimensional	Tests for enabling/disabling $foo{$x, $y} => $foo
 t/lib/feature/nonesuch		Tests for enabling/disabling nonexistent feature
 t/lib/feature/removed		Tests for enabling/disabling removed feature
 t/lib/feature/say		Tests for enabling/disabling say feature
+t/lib/feature/stringification	Tests for enabling/disabling stringification feature
 t/lib/feature/switch		Tests for enabling/disabling switch feature
 t/lib/h2ph.h			Test header file for h2ph
 t/lib/h2ph.pht			Generated output from h2ph.h by h2ph, for comparison

cop.h

@@ -576,6 +576,8 @@ string C<p>, creating the package if necessary.
 #define CopHINTHASH_get(c)	((COPHH*)((c)->cop_hints_hash))
 #define CopHINTHASH_set(c,h)	((c)->cop_hints_hash = (h))
 
+#define CopFEATURES_setfrom(c, o) ((c)->cop_features = (o)->cop_features)
+
 /*
 =for apidoc Am|SV *|cop_hints_fetch_pvn|const COP *cop|const char *keypv|STRLEN keylen|U32 hash|U32 flags
 

feature.h

@@ -26,10 +26,11 @@
 #define FEATURE_SAY_BIT                  0x0800
 #define FEATURE_SIGNATURES_BIT           0x1000
 #define FEATURE_STATE_BIT                0x2000
-#define FEATURE_SWITCH_BIT               0x4000
-#define FEATURE_TRY_BIT                  0x8000
-#define FEATURE_UNIEVAL_BIT              0x10000
-#define FEATURE_UNICODE_BIT              0x20000
+#define FEATURE_STRINGIFICATION_BIT      0x4000
+#define FEATURE_SWITCH_BIT               0x8000
+#define FEATURE_TRY_BIT                  0x10000
+#define FEATURE_UNIEVAL_BIT              0x20000
+#define FEATURE_UNICODE_BIT              0x40000
 
 #define FEATURE_BUNDLE_DEFAULT	0
 #define FEATURE_BUNDLE_510	1
@@ -159,6 +160,13 @@
 	 FEATURE_IS_ENABLED_MASK(FEATURE_MYREF_BIT) \
     )
 
+#define FEATURE_STRINGIFICATION_IS_ENABLED \
+    ( \
+	CURRENT_FEATURE_BUNDLE <= FEATURE_BUNDLE_527 \
+     || (CURRENT_FEATURE_BUNDLE == FEATURE_BUNDLE_CUSTOM && \
+	 FEATURE_IS_ENABLED_MASK(FEATURE_STRINGIFICATION_BIT)) \
+    )
+
 #define FEATURE_UNICODE_IS_ENABLED \
     ( \
 	(CURRENT_FEATURE_BUNDLE >= FEATURE_BUNDLE_511 && \
@@ -337,6 +345,11 @@ S_magic_sethint_feature(pTHX_ SV *keysv, const char *keypv, STRLEN keylen,
                 mask = FEATURE_STATE_BIT;
                 break;
             }
+            else if (keylen == sizeof("feature_stringification")-1
+                 && memcmp(subf+1, "tringification", keylen - sizeof("feature_")) == 0) {
+                mask = FEATURE_STRINGIFICATION_BIT;
+                break;
+            }
             else if (keylen == sizeof("feature_switch")-1
                  && memcmp(subf+1, "witch", keylen - sizeof("feature_")) == 0) {
                 mask = FEATURE_SWITCH_BIT;

lib/feature.pm

@@ -23,19 +23,20 @@ our %feature = (
     postderef_qq         => 'feature_postderef_qq',
     unicode_eval         => 'feature_unieval',
     declared_refs        => 'feature_myref',
+    stringification      => 'feature_stringification',
     unicode_strings      => 'feature_unicode',
     multidimensional     => 'feature_multidimensional',
     bareword_filehandles => 'feature_bareword_filehandles',
 );
 
 our %feature_bundle = (
-    "5.10"    => [qw(bareword_filehandles indirect multidimensional say state switch)],
-    "5.11"    => [qw(bareword_filehandles indirect multidimensional say state switch unicode_strings)],
-    "5.15"    => [qw(bareword_filehandles current_sub evalbytes fc indirect multidimensional say state switch unicode_eval unicode_strings)],
-    "5.23"    => [qw(bareword_filehandles current_sub evalbytes fc indirect multidimensional postderef_qq say state switch unicode_eval unicode_strings)],
-    "5.27"    => [qw(bareword_filehandles bitwise current_sub evalbytes fc indirect multidimensional postderef_qq say state switch unicode_eval unicode_strings)],
-    "all"     => [qw(bareword_filehandles bitwise current_sub declared_refs evalbytes fc indirect isa multidimensional postderef_qq refaliasing say signatures state switch try unicode_eval unicode_strings)],
-    "default" => [qw(bareword_filehandles indirect multidimensional)],
+    "5.10"    => [qw(bareword_filehandles indirect multidimensional say state stringification switch)],
+    "5.11"    => [qw(bareword_filehandles indirect multidimensional say state stringification switch unicode_strings)],
+    "5.15"    => [qw(bareword_filehandles current_sub evalbytes fc indirect multidimensional say state stringification switch unicode_eval unicode_strings)],
+    "5.23"    => [qw(bareword_filehandles current_sub evalbytes fc indirect multidimensional postderef_qq say state stringification switch unicode_eval unicode_strings)],
+    "5.27"    => [qw(bareword_filehandles bitwise current_sub evalbytes fc indirect multidimensional postderef_qq say state stringification switch unicode_eval unicode_strings)],
+    "all"     => [qw(bareword_filehandles bitwise current_sub declared_refs evalbytes fc indirect isa multidimensional postderef_qq refaliasing say signatures state stringification switch try unicode_eval unicode_strings)],
+    "default" => [qw(bareword_filehandles indirect multidimensional stringification)],
 );
 
 $feature_bundle{"5.12"} = $feature_bundle{"5.11"};
@@ -431,6 +432,17 @@ C<try> are caught by executing the body of the C<catch> block.
 
 For more information, see L<perlsyn/"Try Catch Exception Handling">.
 
+=head2 The 'stringification' feature
+
+This feature enables converting references that have no string
+overloading into strings as described in L<perlref>.  It is enabled by
+default, but can be turned off to disable such conversions.
+
+Disabling this feature does not prevent numeric conversions.
+
+This feature is enabled under this name from Perl 5.34 onwards.  In
+previous versions it was simply on all the time.
+
 =head1 FEATURE BUNDLES
 
 It's possible to load multiple features together, using
@@ -444,64 +456,69 @@ The following feature bundles are available:
   bundle    features included
   --------- -----------------
   :default  indirect multidimensional
-            bareword_filehandles
+            bareword_filehandles stringification
 
   :5.10     bareword_filehandles indirect
-            multidimensional say state switch
+            multidimensional say state stringification
+            switch
 
   :5.12     bareword_filehandles indirect
-            multidimensional say state switch
-            unicode_strings
+            multidimensional say state stringification
+            switch unicode_strings
 
   :5.14     bareword_filehandles indirect
-            multidimensional say state switch
-            unicode_strings
+            multidimensional say state stringification
+            switch unicode_strings
 
   :5.16     bareword_filehandles current_sub evalbytes
             fc indirect multidimensional say state
-            switch unicode_eval unicode_strings
+            stringification switch unicode_eval
+            unicode_strings
 
   :5.18     bareword_filehandles current_sub evalbytes
             fc indirect multidimensional say state
-            switch unicode_eval unicode_strings
+            stringification switch unicode_eval
+            unicode_strings
 
   :5.20     bareword_filehandles current_sub evalbytes
             fc indirect multidimensional say state
-            switch unicode_eval unicode_strings
+            stringification switch unicode_eval
+            unicode_strings
 
   :5.22     bareword_filehandles current_sub evalbytes
             fc indirect multidimensional say state
-            switch unicode_eval unicode_strings
+            stringification switch unicode_eval
+            unicode_strings
 
   :5.24     bareword_filehandles current_sub evalbytes
             fc indirect multidimensional postderef_qq
-            say state switch unicode_eval
-            unicode_strings
+            say state stringification switch
+            unicode_eval unicode_strings
 
   :5.26     bareword_filehandles current_sub evalbytes
             fc indirect multidimensional postderef_qq
-            say state switch unicode_eval
-            unicode_strings
+            say state stringification switch
+            unicode_eval unicode_strings
 
   :5.28     bareword_filehandles bitwise current_sub
             evalbytes fc indirect multidimensional
-            postderef_qq say state switch unicode_eval
-            unicode_strings
+            postderef_qq say state stringification
+            switch unicode_eval unicode_strings
 
   :5.30     bareword_filehandles bitwise current_sub
             evalbytes fc indirect multidimensional
-            postderef_qq say state switch unicode_eval
-            unicode_strings
+            postderef_qq say state stringification
+            switch unicode_eval unicode_strings
 
   :5.32     bareword_filehandles bitwise current_sub
             evalbytes fc indirect multidimensional
-            postderef_qq say state switch unicode_eval
-            unicode_strings
+            postderef_qq say state stringification
+            switch unicode_eval unicode_strings
 
   :5.34     bareword_filehandles bitwise current_sub
             evalbytes fc indirect multidimensional
-            postderef_qq say state switch unicode_eval
-            unicode_strings
+            postderef_qq say state stringification
+            switch unicode_eval unicode_strings
 
   :5.36     bareword_filehandles bitwise current_sub
             evalbytes fc indirect multidimensional

op.c

@@ -9425,6 +9425,7 @@ Perl_newSTATEOP(pTHX_ I32 flags, char *label, OP *o)
     cop->cop_seq = seq;
     cop->cop_warnings = DUP_WARNINGS(PL_curcop->cop_warnings);
     CopHINTHASH_set(cop, cophh_copy(CopHINTHASH_get(PL_curcop)));
+    CopFEATURES_setfrom(cop, PL_curcop);
     if (label) {
 	Perl_cop_store_label(aTHX_ cop, label, strlen(label), utf8);
 

pod/perldiag.pod

@@ -413,6 +413,11 @@ assigning through that reference.  For example
     $r = do {my @a; \$#a};
     $$r = 503
 
+=item Attempt to stringify reference under no feature stringification
+
+(F) You tried to use a reference that has no string overloading in
+string context in lexical context of C<no feature "stringification";>
+
 =item Attempt to use reference as lvalue in substr
 
 (W substr) You supplied a reference as the first argument to substr()

regen/feature.pl

@@ -41,6 +41,7 @@ BEGIN
     multidimensional => 'multidimensional',
     bareword_filehandles => 'bareword_filehandles',
     try             => 'try',
+    stringification => 'stringification',
 );
 
 # NOTE: If a feature is ever enabled in a non-contiguous range of Perl
@@ -50,15 +51,16 @@ BEGIN
 # 5.odd implies the next 5.even, but an explicit 5.even can override it.
 
 # features bundles
-use constant V5_9_5 => sort qw{say state switch indirect multidimensional bareword_filehandles};
+use constant V5_9_5 => sort qw{say state switch indirect multidimensional bareword_filehandles
+                               stringification};
 use constant V5_11  => sort ( +V5_9_5, qw{unicode_strings} );
 use constant V5_15  => sort ( +V5_11, qw{unicode_eval evalbytes current_sub fc} );
 use constant V5_23  => sort ( +V5_15, qw{postderef_qq} );
 use constant V5_27  => sort ( +V5_23, qw{bitwise} );
 
 my %feature_bundle = (
     all     => [ sort keys %feature ],
-    default => [ qw{indirect multidimensional bareword_filehandles} ],
+    default => [ qw{indirect multidimensional bareword_filehandles stringification} ],
     # using 5.9.5 features bundle
     "5.9.5" => [ +V5_9_5 ],
     "5.10"  => [ +V5_9_5 ],
@@ -836,6 +838,17 @@ =head2 The 'try' feature.
 
 For more information, see L<perlsyn/"Try Catch Exception Handling">.
 
+=head2 The 'stringification' feature
+
+This feature enables converting references that have no string
+overloading into strings as described in L<perlref>.  It is enabled by
+default, but can be turned off to disable such conversions.
+
+Disabling this feature does not prevent numeric conversions.
+
+This feature is enabled under this name from Perl 5.34 onwards.  In
+previous versions it was simply on all the time.
+
 =head1 FEATURE BUNDLES
 
 It's possible to load multiple features together, using

sv.c

@@ -31,6 +31,7 @@
 #define PERL_IN_SV_C
 #include "perl.h"
 #include "regcomp.h"
+#include "feature.h"
 #ifdef __VMS
 # include <rms.h>
 #endif
@@ -3105,6 +3106,11 @@ Perl_sv_2pv_flags(pTHX_ SV *const sv, STRLEN *const lp, const U32 flags)
 	    if (lp)
 		*lp = len;
 	    SAVEFREEPV(buffer);
+
+            if (!FEATURE_STRINGIFICATION_IS_ENABLED) {
+                Perl_croak(aTHX_ "Attempt to stringify reference under no feature stringification");
+            }
+
 	    return retval;
 	}
     }

t/lib/feature/stringification

@@ -0,0 +1,29 @@
+Test no feature stringification
+
+__END__
+# NAME simple
+# default on
+my $x = \1;
+my $y = "$x";
+# on in bundles
+use v5.10.0;
+$y = "$x";
+use v5.32.0;
+$y = "$x";
+use feature ":5.32.0"; # feature and use v end up different under the hood.
+$y = "$x";
+no feature "stringification";
+$y = "$x";
+EXPECT
+OPTIONS fatal
+Attempt to stringify reference under no feature stringification at - line 12.
+########
+# NAME overloaded
+package Foo {
+    use overload '""' => sub { "ABC" };
+};
+my $x = bless {}, "Foo";
+no feature "stringification";
+print $x, "\n";
+EXPECT
+ABC