not ready to be part of the standard build yet; this is just a checkpoint.

R=rsc
DELTA=361  (361 added, 0 deleted, 0 changed)
OCL=30782
CL=30785

R=rsc
APPROVED=rsc
DELTA=95  (40 added, 14 deleted, 41 changed)
OCL=30727
CL=30784

R=ken
OCL=30783
CL=30783

echo back context of call in error if likely to be useful.

For example, if os.Open("/etc/passwd", os.O_RDONLY)
fails with syscall.EPERM, it returns as the os.Error

	&PathError{
		Op: "open",
		Path: "/etc/passwd"
		Error: os.EPERM
	}

which formats as

	open /etc/passwd: permission denied

Not converted:

	datafmt
	go/...
	google/...
	regexp
	tabwriter
	template

R=r
DELTA=1153  (561 added, 156 deleted, 436 changed)
OCL=30738
CL=30781

R=ken
OCL=30760
CL=30779

R=r
DELTA=51  (4 added, 4 deleted, 43 changed)
OCL=30759
CL=30778

R=rsc
DELTA=11  (11 added, 0 deleted, 0 changed)
OCL=30774
CL=30774

package main
type t interface
type t interface{ m(map[t]bool) }
type m map[t] int

making it work without the forward declaration will require a second pass.

R=ken
OCL=30773
CL=30773

R=ken
OCL=30768
CL=30768

const foo = []int{1,2}

x.go:3: expression must be a constant

instead of

x.go:3: fatal error: gettype: addtop

R=ken
OCL=30767
CL=30767

wreck.mtv=; cat x.go
package main
var x = string.Split()
wreck.mtv=; 6g x.go
x.go:2: type string used as expression
x.go:2: undefined DOT Split on string
x.go:3: illegal types for operand: AS
	undefined
wreck.mtv=;

BUG=1938751
R=ken
OCL=30766
CL=30766

func foo(y) { }

was:
x.go:2: NONAME-y G0 u(1) a(1) l(77) x(-1000000000) is not a type

now:
x.go:2: y is not a type

R=ken
OCL=30764
CL=30764

new flag -A enables it during mkbuiltin.
avoids mysterious errors in programs
that refer to any accidentally.

R=ken
OCL=30763
CL=30763

TBR=r
OCL=30757
CL=30757

R=ken
OCL=30593
CL=30756

won't submit unless 30586 goes in.

R=r
DELTA=94  (65 added, 16 deleted, 13 changed)
OCL=30592
CL=30755

Allow indexing of string type, but not pointer to string type.
Do not allow indexing of pointer to map type.

R=r
DELTA=18  (14 added, 0 deleted, 4 changed)
OCL=30586
CL=30754

R=r
DELTA=40  (30 added, 2 deleted, 8 changed)
OCL=30742
CL=30753

R=r
DELTA=19  (0 added, 19 deleted, 0 changed)
OCL=30739
CL=30751

goroutine. arm only.

R=rsc
APPROVED=rsc
DELTA=5  (3 added, 2 deleted, 0 changed)
OCL=30644
CL=30746

R=rsc
APPROVED=rsc
DELTA=976  (164 added, 237 deleted, 575 changed)
OCL=30705
CL=30743

TBR=r
OCL=30741
CL=30741

R=r
DELTA=32  (0 added, 3 deleted, 29 changed)
OCL=30718
CL=30725

R=rsc
APPROVED=r
DELTA=131  (39 added, 10 deleted, 82 changed)
OCL=30669
CL=30723

R=r
OCL=30719
CL=30719

R=austin
DELTA=352  (67 added, 196 deleted, 89 changed)
OCL=30694
CL=30713

and return the number of bytes copied.

R=r
DELTA=18  (6 added, 0 deleted, 12 changed)
OCL=30693
CL=30712

R=rsc
APPROVED=rsc
DELTA=8  (0 added, 0 deleted, 8 changed)
OCL=30692
CL=30695

R=rsc
APPROVED=rsc
DELTA=722  (722 added, 0 deleted, 0 changed)
OCL=30660
CL=30691

Request".
Use chunked Transfer-Encoding for all POSTs.
Implement chunked reading.
Change http.Request.write to be HTTP/1.1 only.

R=rsc
APPROVED=rsc
DELTA=178  (123 added, 26 deleted, 29 changed)
OCL=30563
CL=30673

R=r
DELTA=69  (37 added, 3 deleted, 29 changed)
OCL=30661
CL=30667

errors introduced in CL 30601

R=austin
DELTA=6  (3 added, 0 deleted, 3 changed)
OCL=30663
CL=30665

do not bother warning about marks left
on stack after syntax errors.

leave OCONV nodes in tree to avoid type errors
arising from multiple walks.

R=ken
OCL=30639
CL=30662

R=rsc
DELTA=7  (5 added, 0 deleted, 2 changed)
OCL=30657
CL=30659

R=rsc
DELTA=9  (0 added, 0 deleted, 9 changed)
OCL=30658
CL=30658

- morestack and gosave/gogo/gocall support
- memclr and memset from inferno
- bugfixes in _rt0_arm

R=rsc
APPROVED=rsc
DELTA=304  (174 added, 36 deleted, 94 changed)
OCL=30636
CL=30642

R=rsc
DELTA=61  (48 added, 0 deleted, 13 changed)
OCL=30616
CL=30619

so implement the check manually.
sigh.

R=r
DELTA=17  (6 added, 0 deleted, 11 changed)
OCL=30606
CL=30612

because Url.Path already starts with one.
Avoid crashing in Request.ParseForm if there is no body.

R=rsc
APPROVED=rsc
DELTA=5  (4 added, 0 deleted, 1 changed)
OCL=30552
CL=30607

R=r
DELTA=7  (6 added, 0 deleted, 1 changed)
OCL=30596
CL=30605