code review 812043: gc: add panic and recover (still unimplemented in runtime)

gc: add panic and recover (still unimplemented in runtime)
main semantic change is to enforce single argument to panic.

runtime: change to 1-argument panic.
use String method on argument if it has one.

[rsc, 2010-03-30 08:39:41]

Hello ken2, r (cc: golang-dev@googlegroups.com),

I'd like you to review this change.

[r, 2010-03-30 17:09:52]

http://codereview.appspot.com/812043/diff/2001/3006
File src/cmd/gc/typecheck.c (right):

http://codereview.appspot.com/812043/diff/2001/3006#newcode1034
src/cmd/gc/typecheck.c:1034: yyerror("too many arguments to recover", n->op);
is n->op right to print?

http://codereview.appspot.com/812043/diff/2001/3011
File src/pkg/runtime/print.c (right):

http://codereview.appspot.com/812043/diff/2001/3011#newcode352
src/pkg/runtime/print.c:352: void
could use a one-line introduction

http://codereview.appspot.com/812043/diff/2001/3011#newcode385
src/pkg/runtime/print.c:385: callstring(m->ifn, e.data, &s);
slight change of convention but it seems this should be callString

http://codereview.appspot.com/812043/diff/2001/3011#newcode392
src/pkg/runtime/print.c:392: switch(e.type->kind & ~KindNoPointers) {
what happens if i panic(&integer)?

[rsc, 2010-03-30 17:44:08]

PTAL

> http://codereview.appspot.com/812043/diff/2001/3006#newcode1034
> src/cmd/gc/typecheck.c:1034: yyerror("too many arguments to recover",
> n->op);
> is n->op right to print?

no, it's ignored, deleted.

> http://codereview.appspot.com/812043/diff/2001/3011#newcode352
> src/pkg/runtime/print.c:352: void
> could use a one-line introduction

done

> http://codereview.appspot.com/812043/diff/2001/3011#newcode385
> src/pkg/runtime/print.c:385: callstring(m->ifn, e.data, &s);
> slight change of convention but it seems this should be callString

done

> http://codereview.appspot.com/812043/diff/2001/3011#newcode392
> src/pkg/runtime/print.c:392: switch(e.type->kind & ~KindNoPointers) {
> what happens if i panic(&integer)?

nothing bad - it prints *int(???) as the value.
the KindNoPointers is an informational high bit that
gets set in the type kind to say "this kind of type
never has pointers embedded inside it".  it just gets in
the way here.  (i could take the mask out but
then the case for int would be case KindInt|KindNoPointers.)

russ

[r, 2010-03-30 17:46:32]

LGTM

[rsc, 2010-03-30 17:53:19]

*** Submitted as http://code.google.com/p/go/source/detail?r=62cf91510b15 ***

gc: add panic and recover (still unimplemented in runtime)
main semantic change is to enforce single argument to panic.

runtime: change to 1-argument panic.
use String method on argument if it has one.

R=ken2, r
CC=golang-dev
http://codereview.appspot.com/812043