- simplified assignment checking by removing duplicate code
- implemented field lookup (methods, structs, embedded fields)
- importing methods (not just parsing them)
- type-checking functions and methods
- typechecking more statements (inc/dec, select, return)
- tracing support for easier debugging
- handling nil more correctly (comparisons)
- initial support for [...]T{} arrays
- initial support for method expressions
- lots of bug fixes

All packages under pkg/go as well as pkg/exp/types typecheck
now with pkg/exp/gotype applied to them; i.e., a significant
amount of typechecking works now (several statements are not
implemented yet, but handling statements is almost trivial in
comparison with typechecking expressions).

R=rsc
CC=golang-dev
https://golang.org/cl/6768063

Use wrapper functions to tell scheduler what we are doing.

With this patch, and a separate patch to the go tool, all the
cgo tests pass with gccgo.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/6812058

* Use -fgo-pkgpath and -gccgopkgpath rather than -fgo-prefix
  and -gccgoprefix.
* Define GOPKGPATH when compiling .c or .s files for gccgo.
* Use -fgo-relative-import-path.
* Produce .o files for gccgo, not .[568] files.
* Pass -E when linking if using cgo.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/6820064

This supports writing different .c/.s code when using gccgo.

R=golang-dev, dsymonds, iant, rsc
CC=golang-dev
https://golang.org/cl/6823055

The idea is to (1) process ninit of all nodes,
and (2) put instrumentation of ninit into the nodes themselves (not the top-level statement ninit).
Fixes #4304.

R=golang-dev, rsc
CC=golang-dev, lvd
https://golang.org/cl/6818049

When local declarations needed unexported types, these could
be missing in the export data.

Fixes build with -gcflags -lll, except for exp/gotype.

R=golang-dev, rsc, lvd
CC=golang-dev
https://golang.org/cl/6813067

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/6612064

Fixes #4323.

R=rsc, lvd, golang-dev
CC=golang-dev
https://golang.org/cl/6815061

Helps with issue 2703.

R=dave, minux.ma, rsc
CC=golang-dev
https://golang.org/cl/5536078

This should make the compiler emit errors specific to the bounds checking instead of overflow errors on the underlying types.

Updates #4232.

R=rsc
CC=golang-dev
https://golang.org/cl/6783054

This is an attempt at making the interaction between
these three constructs clearer. Specifically:

- return statements terminate a function, execute deferred
  functions, return to the caller, and then execution
  continues after the call

- panic calls terminate a function, execute deferred
  functions, return to the caller, and then re-panic

- deferred functions are executed before a function _returns_
  to its caller

The hope is that with this change it becomes clear when a
deferred function is executed (when a function returns),
and when it is not (when a program exits).

R=r, rsc, iant, ken, iant
CC=golang-dev
https://golang.org/cl/6736071

The 'type' field of Itab will be used by the garbage collector.

R=rsc
CC=golang-dev
https://golang.org/cl/6815059

Incorrect cast was causing panics when
calling String() on dnsMsg with dnsRR_A
answers.

R=golang-dev, dave, rsc
CC=golang-dev
https://golang.org/cl/6818043

R=golang-dev
CC=golang-dev, remyoudompheng, rsc
https://golang.org/cl/6780059

Plan 9 and Go's lib9/fmt disagree on whether %#x includes the 0x prefix
when printing 0, because ANSI C gave bad advice long ago.

Avoiding that case makes binaries compiled on different systems compatible.

R=ken2
CC=akumar, golang-dev
https://golang.org/cl/6814066

This caused more problems than it was worth.

Fixes #4301.
Fixes #4317.

R=golang-dev, minux.ma, rsc
CC=golang-dev
https://golang.org/cl/6818076

The move to 64-bit ints in 6g made componentgen ineffective.
In componentgen, the code already selects which values it can handle.

On amd64:
benchmark                 old ns/op    new ns/op    delta
BenchmarkBinaryTree17    9477970000   9582314000   +1.10%
BenchmarkFannkuch11      5928750000   5255080000  -11.36%
BenchmarkGobDecode         37103040     31451120  -15.23%
BenchmarkGobEncode         16042490     16844730   +5.00%
BenchmarkGzip             811337400    741373600   -8.62%
BenchmarkGunzip           197928700    192844500   -2.57%
BenchmarkJSONEncode       224164100    140064200  -37.52%
BenchmarkJSONDecode       258346800    231829000  -10.26%
BenchmarkMandelbrot200      7561780      7601615   +0.53%
BenchmarkParse             12970340     11624360  -10.38%
BenchmarkRevcomp         1969917000   1699137000  -13.75%
BenchmarkTemplate         296182000    263117400  -11.16%

R=nigeltao, dave, daniel.morsing
CC=golang-dev
https://golang.org/cl/6821052

R=golang-dev, minux.ma
CC=golang-dev
https://golang.org/cl/6811059

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/6826044

defined by the PLTE chunk. Such pixels decode to opaque black,
which matches what libpng does.

Fixes #4319.

On my reading, the PNG spec isn't clear whether palette index values
outside of those defined by the PLTE chunk is an error, and if not,
what to do.

Libpng 1.5.3 falls back to opaque black. png_set_PLTE says:

/* Changed in libpng-1.2.1 to allocate PNG_MAX_PALETTE_LENGTH instead
 * of num_palette entries, in case of an invalid PNG file that has
 * too-large sample values.
 */
png_ptr->palette = (png_colorp)png_calloc(png_ptr,
        PNG_MAX_PALETTE_LENGTH * png_sizeof(png_color));

ImageMagick 6.5.7 returns an error:

$ convert -version
Version: ImageMagick 6.5.7-8 2012-08-17 Q16 http://www.imagemagick.org
Copyright: Copyright (C) 1999-2009 ImageMagick Studio LLC
Features: OpenMP
$ convert packetloss.png x.bmp
convert: Invalid colormap index `packetloss.png' @ image.c/SyncImage/3849.

R=r
CC=golang-dev
https://golang.org/cl/6822065

Fixes #4297.

R=golang-dev, gri
CC=golang-dev
https://golang.org/cl/6817045

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/6815062

Fixes #4324.

R=r
CC=golang-dev
https://golang.org/cl/6822062

Fixes #1390.

R=golang-dev, minux.ma, adg, agl
CC=golang-dev
https://golang.org/cl/6631044

Fixes #4314.

R=r, rsc
CC=golang-dev
https://golang.org/cl/6822059

Fixes #2874.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/6820068

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/6812060

Fixes build, too.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/6775088

R=r, mpvl
CC=golang-dev
https://golang.org/cl/6818067

Tailorings are represented by removing and reinserting entries from a linked list.
After all tailorings are done, missing weights are computed and verified.
This implementation assumes that entries that are used in expansions are not
reinserted at a later point.  This considerably simplifies the implementation.

R=r
CC=golang-dev
https://golang.org/cl/6739052

incremental comparisons. Instead, processing is now done directly on colElems.
As a result, the size of the weights array is now reduced by 75%.
Details:
- Primary value of type 1 colElem is shifted by 1 bit so that primaries
  of all types can be compared without shifting.
- Quaternary values are now stored in the colElem itself. This is possible
  as quaternary values other than 0 or maxQuaternary are only needed when other
  values are ignored.
- Simplified processWeights by removing cases that are needed for ICU but not
  for us (our CJK primary values fit in a single value).

R=r
CC=golang-dev
https://golang.org/cl/6817054

R=r
CC=golang-dev
https://golang.org/cl/6727049

I fixed a bug in gccgo that was causing it to only give an
error for the first package that was imported and not used.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/6813058

As discussed in the following thread:
https://groups.google.com/forum/?fromgroups=#!topic/golang-dev/emeJffxWhVo

This is required to enable applications such as `less` to use something
other than stdin as the controlling terminal.

R=dave, iant
CC=bradfitz, golang-dev
https://golang.org/cl/6785057

R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/6775083

It is common to close network connection while another goroutine is
blocked reading on another goroutine. This sequence corresponds to
windows calls to WSARecv to start io, followed by GetQueuedCompletionStatus
that blocks until io completes, and, finally, closesocket called from
another thread. We were expecting that closesocket would unblock
GetQueuedCompletionStatus, and it does, but not always
(http://code.google.com/p/go/issues/detail?id=4170#c5). Also that sequence
results in connection is being reset.

This CL inserts CancelIo between GetQueuedCompletionStatus and closesocket,
and waits for both WSARecv and GetQueuedCompletionStatus to complete before
proceeding to closesocket.  This seems to fix both connection resets and
issue 4170. It also makes windows code behave similar to unix version.

Unfortunately, CancelIo needs to be called on the same thread as WSARecv.
So we have to employ strategy we use for connections with deadlines to
every connection now. It means, there are 2 unavoidable thread switches
for every io. Some newer versions of windows have new CancelIoEx api that
doesn't have these drawbacks, and this CL uses this capability when available.
As time goes by, we should have less of CancelIo and more of CancelIoEx
systems. Computers with CancelIoEx are also not affected by issue 4195 anymore.

Fixes #3710
Fixes #3746
Fixes #4170
Partial fix for issue 4195

R=golang-dev, mikioh.mikioh, bradfitz, rsc
CC=golang-dev
https://golang.org/cl/6604072

benchmark                     old ns/op    new ns/op    delta
BenchmarkDecodeBaseline         3155638      2783998  -11.78%
BenchmarkDecodeProgressive      4008088      3660310   -8.68%

R=r, bradfitz
CC=golang-dev
https://golang.org/cl/6775072

Fixes #4296.

R=golang-dev, alex.brainman
CC=golang-dev
https://golang.org/cl/6815044

Keys use ==; values use deep equality. Also remove the word 'member'.
Fixes #4258.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/6812055

Remove trailing whitespace in comments.
No other changes.

R=r
CC=golang-dev
https://golang.org/cl/6815053