fixup better error reporting of non-scalar vars used as named params

Author: leonerd

pod/perldiag.pod

@@ -248,6 +248,15 @@ sigil; for example:
 
     sub foo ($x, $, $y = 1, @z) {}
 
+=item A named signature parameter must start with '$'
+
+(F) Each subroutine signature parameter declaration that declares a named
+parameter must start with a scalar variable sigil; for example:
+
+    sub foo (:$x, :$y, :$z) {}
+
+Array and hash variables are not permitted as named parameters.
+
 =item A slurpy parameter may not have a default value
 
 (F) Only scalar subroutine signature parameters may have a default value;
@@ -4865,13 +4874,6 @@ C<sysread()>ing a file, or when seeking past the end of a scalar opened
 for I/O (in anticipation of future reads and to imitate the behavior
 with real files).
 
-=item Only a scalar parameter may be named
-
-(F) An attempt was made to use an array or hash variable as a named parameter.
-
-    sub foo (:@name) {...}
-    sub foo (:%name) {...}
-
 =item Only scalar fields can take a :param attribute
 
 (F) You tried to apply the C<:param> attribute to an array or hash field.

t/lib/croak/signatures

@@ -216,6 +216,21 @@ EXPECT
 Illegal operator following parameter in a subroutine signature at - line 2, near "(:$a :"
 syntax error at - line 2, near "(:$a :"
 ########
+sub named (:@x) { }
+EXPECT
+A named signature parameter must start with '$' at - line 2, near "(:@"
+syntax error at - line 2, near ":@x"
+########
+sub named (:%x) { }
+EXPECT
+A named signature parameter must start with '$' at - line 2, near "(:%"
+syntax error at - line 2, near ":%x"
+########
+sub t094_named (:123) { }
+EXPECT
+A named signature parameter must start with '$' at - line 2, near "(:1"
+syntax error at - line 2, near "(:123"
+########
 sub t097 ($a { }) { }
 EXPECT
 Illegal operator following parameter in a subroutine signature at - line 2, near "($a { }"

toke.c

@@ -5508,7 +5508,7 @@ yyl_sigvar(pTHX_ char *s)
             break;
         }
         if (is_named && sigil != '$') {
-            yyerror("Only a scalar parameter may be named");
+            yyerror("A named signature parameter must start with '$'");
             break;
         }
         s = skipspace(s);
@@ -5586,7 +5586,10 @@ yyl_sigvar(pTHX_ char *s)
 
     default:
         PL_in_my = 0;
-        yyerror("A signature parameter must start with '$', '@' or '%'");
+        if(is_named)
+            yyerror("A named signature parameter must start with '$'");
+        else
+            yyerror("A signature parameter must start with '$', '@' or '%'");
         /* very crude error recovery: skip to likely next signature
          * element */
         while (*s && *s != '$' && *s != '@' && *s != '%' && *s != ')')