When a line directive was encountered we would push a new 'z' entry into
the history to indicate the start of new file attributation, and a 'Z'
entry to change line numbering.  However we didn't pop the 'z' entry, so
we were actually corrupting the history stack.  The most obvious
occurance of this was in the code that build the symbol tables for the
DWARF information - where an internal stack in the linker would overflow
when more than a few line directives were encountered in a single stack
(Issue 1878).  So now we pop the 'z' entry when we encounter the end of
the file that the directive was in, which maintains the history stack
integrity.

Also, although new 'z' entries for new files had relative paths
expanded, the same was not done for line directives.  Now we do it for
line directives also - so that the now correct DWARF information has the
full path available.

Fixes #1878.

R=rsc
CC=golang-dev
https://golang.org/cl/4938042

Add -V flag to 6c command line to keep them fixed.

R=ken2
CC=golang-dev
https://golang.org/cl/4930046

Introduce extra scope for the variable declared by a
TypeSwitchGuard so that it doesn't conflict with vars
declared by the initial SimpleStmt of a type switch.

This is a replacement for CL 4896053 which caused
a build breakage.

Also:
- explicitly detect type switches (as opposed to detecting
  expression switches and then do extra testing for type switches)
- fix all outstanding TODOs in parser.go
- ran all tests

R=rsc
CC=golang-dev
https://golang.org/cl/4914044

This adds http.MaxBytesReader, similar to io.LimitReader,
but specific to http, and for preventing a class of DoS
attacks.

This also makes the 10MB ParseForm limit optional (if
not already set by a MaxBytesReader), documents it,
and also adds "PUT" as a valid verb for parsing forms
in the request body.

Improves issue 2093 (DoS protection)
Fixes #2165 (PUT form parsing)

R=golang-dev, adg
CC=golang-dev
https://golang.org/cl/4921049

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/4937047

Make the stack traces more readable for new
Go programmers while preserving their utility for old hands.

- Change status number [4] to string.
- Elide frames in runtime package (internal details).
- Swap file:line and arguments.
- Drop 'created by' for main goroutine.
- Show goroutines in order of allocation:
  implies main goroutine first if nothing else.

There is no option to get the extra frames back.
Uncomment 'return 1' at the bottom of symtab.c.

$ 6.out
throw: all goroutines are asleep - deadlock!

goroutine 1 [chan send]:
main.main()
       /Users/rsc/g/go/src/pkg/runtime/x.go:22 +0x8a

goroutine 2 [select (no cases)]:
main.sel()
       /Users/rsc/g/go/src/pkg/runtime/x.go:11 +0x18
created by main.main
       /Users/rsc/g/go/src/pkg/runtime/x.go:19 +0x23

goroutine 3 [chan receive]:
main.recv(0xf8400010a0, 0x0)
       /Users/rsc/g/go/src/pkg/runtime/x.go:15 +0x2e
created by main.main
       /Users/rsc/g/go/src/pkg/runtime/x.go:20 +0x50

goroutine 4 [chan receive (nil chan)]:
main.recv(0x0, 0x0)
       /Users/rsc/g/go/src/pkg/runtime/x.go:15 +0x2e
created by main.main
       /Users/rsc/g/go/src/pkg/runtime/x.go:21 +0x66
$

$ 6.out index
panic: runtime error: index out of range

goroutine 1 [running]:
main.main()
        /Users/rsc/g/go/src/pkg/runtime/x.go:25 +0xb9
$

$ 6.out nil
panic: runtime error: invalid memory address or nil pointer dereference
[signal 0xb code=0x1 addr=0x0 pc=0x22ca]

goroutine 1 [running]:
main.main()
        /Users/rsc/g/go/src/pkg/runtime/x.go:28 +0x211
$

$ 6.out panic
panic: panic

goroutine 1 [running]:
main.main()
        /Users/rsc/g/go/src/pkg/runtime/x.go:30 +0x101
$

R=golang-dev, qyzhai, n13m3y3r, r
CC=golang-dev
https://golang.org/cl/4907048

The Go version has 64 character long section names; originally,
in Plan 9, the limit was 16.  To provide compatibility, this
change allows the input length to be either the target length
or the earlier option.	The section name is extended with spaces
where required.

This has been tested to work without regressions in the
Go environment, testing the older alternative has not been
possible yet.

R=rsc
CC=golang-dev
https://golang.org/cl/4650071

Add support for syscalls on openbsd amd64. This is based on the
existing freebsd amd64 implementation.

R=mikioh.mikioh, rsc, yourcomputerpal
CC=golang-dev
https://golang.org/cl/4798060

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/4832047

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/4901054

The EXTERN lines in elf.h already define these.
That's not a problem for most C compilers, but
apparently it is for some copies of the OS X linker.

Fixes #2167.

R=golang-dev, iant
CC=golang-dev
https://golang.org/cl/4936044

from others (such as title) during escaping.

R=r, mikesamuel, dsymonds
CC=golang-dev
https://golang.org/cl/4919042

ast.FilterFile(src, ast.IsExported) has the same
effect as ast.FileExports(src) with this change.

1st step towards removing FileExports - it is
just a special case of FilterFile with this CL.

Added corresponding test.

R=r
CC=golang-dev
https://golang.org/cl/4938041

Fixes #2173.

R=r, rsc
CC=golang-dev
https://golang.org/cl/4941044

R=golang-dev, gri
CC=golang-dev
https://golang.org/cl/4710047

R=golang-dev, gri
CC=golang-dev
https://golang.org/cl/4938045

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/4937045

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/4930044

R=r
CC=golang-dev
https://golang.org/cl/4925041

maketables.go/tables.go
- Properly set combinesForward flag for JamoL and JamoV.
- Fixed Printf bug.
composition.go
- Make insertString use the same control flow as insert.
- Better Hangul and non-Hangul mixing.
forminfo.go
- Fixed bug in compBoundaryBefore that affected a few esoteric cases.
- Buffer overflow now tested in normalize_test.go (other CL).

R=r
CC=golang-dev
https://golang.org/cl/4924041

No external changes.

R=nigeltao
CC=golang-dev
https://golang.org/cl/4940042

R=rsc, r
CC=golang-dev
https://golang.org/cl/4921047

Fixes #2171

This is the real change.

R=adg
CC=golang-dev, r, rsc
https://golang.org/cl/4943041

It was ill-conceived and can be resurrected if needed.

R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/4930043

R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/4921045

R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/4921044

R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/4919044

R=golang-dev, dsymonds, r
CC=golang-dev
https://golang.org/cl/4918043

It's not even using vectors - the references are just examples.

R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/4938043

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/4921041

R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/4932044

R=rsc, gri
CC=golang-dev
https://golang.org/cl/4935046

R=adg, rsc, tarmigan+golang
CC=golang-dev
https://golang.org/cl/4807048

Also update the big example to the new template system.
There are a number of other examples that should be
extracted; this CL serves as an introduction to the
approach.

R=golang-dev, adg
CC=golang-dev
https://golang.org/cl/4923043

Trivial change: just fix the import.

R=golang-dev, adg
CC=golang-dev
https://golang.org/cl/4937043

- templates should be read before any handlers are started
- for app engine use, must use underlying file system to read templates

R=r
CC=golang-dev
https://golang.org/cl/4928042

In the process, rewrite index.go to use slices instead
of vectors, rewrite for-loops into range loops, and
generally simplify code (this code was written before
the launch of go and showed its age).

Also, fix a wrong import in appinit.go.

No significant performance changes (improvements);
most of time is spent elsewhere (measured on an stand-
alone MacBook Pro with SSD disk, running standard
godoc settings: godoc -v -http=:7777 -index).

R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/4875056

R=rsc, r
CC=golang-dev
https://golang.org/cl/4894057

R=golang-dev, dsymonds, r
CC=golang-dev, mikesamuel
https://golang.org/cl/4918041

R=golang-dev
CC=golang-dev
https://golang.org/cl/4873058