new warning "Useless use of sort in scalar context"

Message-ID: <20011119132645.A15034@rafael>

p4raw-id: //depot/perl@13094

diff --git a/op.c b/op.c
index af125aa..6343a03 100644 (file)
--- a/op.c
+++ b/op.c
@@ -1024,6 +1024,9 @@ Perl_scalar(pTHX_ OP *o)
        }
        WITH_THR(PL_curcop = &PL_compiling);
        break;
+    case OP_SORT:
+       if (ckWARN(WARN_VOID))
+           Perl_warner(aTHX_ WARN_VOID, "Useless use of sort in scalar context");
     }
     return o;
 }

diff --git a/pod/perldiag.pod b/pod/perldiag.pod
index a4c6543..aab7831 100644 (file)
--- a/pod/perldiag.pod
+++ b/pod/perldiag.pod
@@ -3844,6 +3844,14 @@ about.
 
 (W) You did C<use re;> without any arguments.   That isn't very useful.
 
+=item Useless use of sort in scalar context
+
+(W void) You used sort in scalar context, as in :
+
+    my $x = sort @y;
+
+This is not very useful, and perl currently optimizes this away.
+
 =item Useless use of %s with no values
 
 (W syntax) You used the push() or unshift() function with no arguments

diff --git a/t/lib/warnings/op b/t/lib/warnings/op
index ab6d773..2fa54b8 100644 (file)
--- a/t/lib/warnings/op
+++ b/t/lib/warnings/op
@@ -36,6 +36,9 @@
        $a ;
        "abc"
 
+     Useless use of sort in scalar context
+       my $x = sort (2,1,3);
+
      Applying %s to %s will act on scalar(%s)
        my $a ; my @a = () ; my %a = () ; my $b = \@a ; my $c = \%a ;
        @a =~ /abc/ ;
@@ -332,6 +335,14 @@ Useless use of getpwnam in void context at - line 52.
 Useless use of getpwuid in void context at - line 53.
 ########
 # op.c
+use warnings 'void' ; close STDIN ;
+my $x = sort (2,1,3);
+no warnings 'void' ;
+$x = sort (2,1,3);
+EXPECT
+Useless use of sort in scalar context at - line 3.
+########
+# op.c
 no warnings 'void' ; close STDIN ;
 1 x 3 ;                        # OP_REPEAT
                        # OP_GVSV