Setting the f flag on length causes the op to be constant folded.

p4raw-id: //depot/perl@33337

diff --git a/opcode.h b/opcode.h
index 82bca2d..65545a4 100644 (file)
--- a/opcode.h
+++ b/opcode.h
@@ -1658,7 +1658,7 @@ EXTCONST U32 PL_opargs[] = {
        0x0001378e,     /* hex */
        0x0001378e,     /* oct */
        0x0001378e,     /* abs */
-       0x0001379c,     /* length */
+       0x0001379e,     /* length */
        0x1322280c,     /* substr */
        0x0022281c,     /* vec */
        0x0122291c,     /* index */

diff --git a/opcode.pl b/opcode.pl
index bcbcbb0..b59af50 100755 (executable)
--- a/opcode.pl
+++ b/opcode.pl
@@ -760,7 +760,7 @@ abs         abs                     ck_fun          fsTu%   S?
 
 # String stuff.
 
-length         length                  ck_lengthconst  isTu%   S?
+length         length                  ck_lengthconst  ifsTu%  S?
 substr         substr                  ck_substr       st@     S S S? S?
 vec            vec                     ck_fun          ist@    S S S
 

diff --git a/t/lib/warnings/7fatal b/t/lib/warnings/7fatal
index dfbb713..6eeac74 100644 (file)
--- a/t/lib/warnings/7fatal
+++ b/t/lib/warnings/7fatal
@@ -285,7 +285,8 @@ time ;
 
 {
     use warnings FATAL => qw(void) ;
-    length "abc" ;
+    $a = "abc";
+    length $a ;
 }
 
 join "", 1,2,3 ;
@@ -293,7 +294,7 @@ join "", 1,2,3 ;
 print "done\n" ;
 EXPECT
 Useless use of time in void context at - line 4.
-Useless use of length in void context at - line 8.
+Useless use of length in void context at - line 9.
 ########
 # TODO ? !$Config{usethreads} && $::UTF8 && ($ENV{PERL_DESTRUCT_LEVEL} || 0) > 1 ? "Parser leaks OPs, which leak shared hash keys" : ''
 
@@ -303,7 +304,8 @@ time ;
 
 {
     use warnings FATAL => qw(void) ;
-    length "abc" ;
+    $a = "abc";
+    length $a ;
 }
 
 join "", 1,2,3 ;
@@ -311,7 +313,7 @@ join "", 1,2,3 ;
 print "done\n" ;
 EXPECT
 Useless use of time in void context at - line 4.
-Useless use of length in void context at - line 8.
+Useless use of length in void context at - line 9.
 ########
 
 use warnings FATAL => 'all';
@@ -362,35 +364,39 @@ Use of uninitialized value $b in scalar chop at - line 7.
 
 use warnings FATAL => 'syntax', NONFATAL => 'void' ;
 
-length "abc";
+$a = "abc";
+length $a;
 print STDERR "The End.\n" ;
 EXPECT
-Useless use of length in void context at - line 4.
+Useless use of length in void context at - line 5.
 The End.
 ########
 
 use warnings FATAL => 'all', NONFATAL => 'void' ;
 
-length "abc";
+$a = "abc";
+length $a;
 print STDERR "The End.\n" ;
 EXPECT
-Useless use of length in void context at - line 4.
+Useless use of length in void context at - line 5.
 The End.
 ########
 
 use warnings FATAL => 'all', NONFATAL => 'void' ;
 
 my $a ; chomp $a;
-length "abc";
+
+$b = "abc" ;
+length $b;
 print STDERR "The End.\n" ;
 EXPECT
-Useless use of length in void context at - line 5.
+Useless use of length in void context at - line 7.
 Use of uninitialized value $a in scalar chomp at - line 4.
 ########
 
 use warnings FATAL => 'void', NONFATAL => 'void' ;
-
-length "abc";
+$a = "abc";
+length $a;
 print STDERR "The End.\n" ;
 EXPECT
 Useless use of length in void context at - line 4.
@@ -399,8 +405,8 @@ The End.
 # TODO ? !$Config{usethreads} && $::UTF8 && ($ENV{PERL_DESTRUCT_LEVEL} || 0) > 1 ? "Parser leaks OPs, which leak shared hash keys" : ''
 
 use warnings NONFATAL => 'void', FATAL => 'void' ;
-
-length "abc";
+$a = "abc";
+length $a;
 print STDERR "The End.\n" ;
 EXPECT
 Useless use of length in void context at - line 4.