[perl #47674] [TODO] :vtable pragma should enable 'self'

[Andrew Whitworth via RT]

With some help from DietCoke, we got most of the problem solved.
However, several tests are failing now, especially those dealing with
overriding the invoke vtable method.

One error specifically caught my eye, from t/pmc/namespace.t:1672:

.sub 'main' :main
    $P0 = newclass 'Override'
    $P1 = new 'Override'
    $P2 = find_method $P1, 'foo'
.end

.namespace [ 'Override' ]

.sub 'find_method' :vtable
    say "Finding method"
.end

With the patch, this test returns an error that we are passing one
parameter, but expecting 0. This is, I assume, desired behavior: We are
passing one parameter (the method name string 'foo'), but 'find_method'
isn't expecting any parameters. Changing the method to this fixes the
problem:

.sub 'find_method' :vtable
  .param string name
  say "Finding method"
.end

I suspect this is desired behavior, because the 'find_method' vtable
method should take the name of the method to find as a parameter
(otherwise, how do you know what to find?)

Some of the other tests deal with object invoking, such as "$P0()". With
the patch, many of these tests are failing because we aren't passing
enough parameters. For instance, the following test is failing because
we are passing 0 parameters, when it expects 1:

.namespace ['Foo']

.sub invoke :vtable
    say "you invoked me!"
    .return()
.end

.sub main :main
    $P0 = newclass "Foo"
    $P1 = new "Foo"
    $P1()
    say "got here"
.end

Changing the invocation to say "$P1($P1)" solves the error, but I doubt
this is desired. The parser is, I assume, trying to suck the object into
the self parameter, but it isn't being passed in the first place. On
invokes, we should be passing the object itself as a "self" parameter,
although I don't know how to make that happen.

On an odd note, generating PASM output of the above example with "$P1()"
and "$P1($P1)" using parrot -o both produce identical PASM files.
Neither generated PASM file executes, they both fail with segmentation
faults. I don't know yet if this is an artifact of the patch, a problem
with the PASM generator, or something else. 

--Andrew Whitworth

Index: compilers/imcc/pcc.c
===================================================================
--- compilers/imcc/pcc.c	(revision 28866)
+++ compilers/imcc/pcc.c	(working copy)
@@ -313,7 +313,8 @@
     SymReg      *regs[2];
 
     /* if this sub is a method, unshift 'self' as first param */
-    if (sub->pcc_sub->pragma & P_METHOD) {
+    if ((sub->pcc_sub->pragma & P_METHOD) ||
+        (IMCC_INFO(interp)->cur_unit->is_vtable_method)) {
         SymReg *self = get_sym(interp, "self");
         if (!self) {
             self       = mk_symreg(interp, "self", 'P');
Index: compilers/imcc/imcc.l
===================================================================
--- compilers/imcc/imcc.l	(revision 28866)
+++ compilers/imcc/imcc.l	(working copy)
@@ -557,7 +557,8 @@
                 (r = IMCC_INFO(interp)->cur_unit->instructions->symregs[0]) &&
                 r->pcc_sub)
             {
-                if ((r->pcc_sub->pragma & P_METHOD) &&
+                if (((r->pcc_sub->pragma & P_METHOD) ||
+                     (IMCC_INFO(interp)->cur_unit->is_vtable_method)) &&
                     !strcmp(yytext, "self")) {
                     valp->sr = mk_ident(interp, "self", 'P');
                     IMCC_INFO(interp)->cur_unit->type |= IMC_HAS_SELF;
Index: t/pmc/namespace.t
===================================================================
--- t/pmc/namespace.t	(revision 28866)
+++ t/pmc/namespace.t	(working copy)
@@ -1679,7 +1679,10 @@
 .namespace [ 'Override' ]
 
 .sub 'find_method' :vtable
-    say "Finding method"
+    .param string name
+    $S0 = "Finding method"
+    $S1 = $S0 . name
+    say $S1
 .end
 CODE
 /Finding method/