Allow the \$ proto to accept any scalar lvalue [perl #91846]

This makes the \$ prototype’s parsing the same as the second argument
to read(), making it possible to create a custom myread() function
that has the same syntax.

This is handled in two places in the prototype-parsing code, to avoid
calling scalar() on the op if another character in \[...] will accept
it.  I don’t know what the consequences of that would be.  So it calls
Perl_op_lvalue_flags in the $ case only if it is not inside brackets.
Then in the ] case it checks to see whether there was a $.

OP_READ, not OP_ENTERSUB, is passed as the type to
Perl_op_lvalue_flags, since OP_ENTERSUB would allow sub foo(\$) to
accept an array as an argument.  OP_RECV and OP_SYSREAD would have
worked, too.

1 files changed, 9 insertions, 0 deletions

diff --git a/pod/perldelta.pod b/pod/perldelta.pod
index 751da25964..d4bc3c359e 100644
--- a/pod/perldelta.pod
+++ b/pod/perldelta.pod
@@ -33,6 +33,15 @@ here, but most should go in the L</Performance Enhancements> section.
 You can now limit the size of an array using C<splice(@a,MAX_LEN)> without
 worrying about warnings.
 
+=head2 The C<\$> prototype accepts any scalar lvalue
+
+The C<\$> and C<\[$]> subroutine prototypes now accept any scalar lvalue
+argument.  Previously they only accepted scalars beginning with C<$> and
+hash and array elements.  This change makes them consistent with the way
+the built-in C<read> and C<recv> functions (among others) parse their
+arguments. This means that one can override the built-in functions with
+custom subroutines that parse their arguments the same way.
+
 =head1 Security
 
 XXX Any security-related notices go here.  In particular, any security