This makes os_test.TestStartProcess test from os package pass.

R=paulzhol, r2, r
CC=golang-dev
https://golang.org/cl/4385052

R=agl1
CC=golang-dev
https://golang.org/cl/4376049

Fixes #1683

R=agl1
CC=golang-dev, rsc
https://golang.org/cl/4367049

R=agl1
CC=golang-dev
https://golang.org/cl/4367051

Fixes #1649.

R=rsc, adg
CC=golang-dev
https://golang.org/cl/4343056

R=adg
CC=golang-dev
https://golang.org/cl/4385051

Fixes #1678.

R=adg, rsc
CC=golang-dev
https://golang.org/cl/4372047

The ld time was dominated by symbol table processing, so
  * increase hash table size
  * emit fewer symbols in gc (just 1 per string, 1 per type)
  * add read-only lookup to avoid creating spurious symbols
  * add linked list to speed whole-table traversals

Breaks dwarf generator (no idea why), so disable dwarf.

Reduces time for 6l to link godoc by 25%.

R=ken2
CC=golang-dev
https://golang.org/cl/4383047

Note that declarations.golden is not using spaces for alignment (so
that the alignment tabs are visible) which is why this change affects
the test cases significantly. gofmt uses spaces for alignment (by default)
and only tabs for indentation.

gofmt -w src misc (no changes)

Fixes #1673.

R=iant
CC=golang-dev
https://golang.org/cl/4388044

"%#v" of a structure with *big.Int's tends to crash a lot otherwise.

R=golang-dev, gri
CC=golang-dev
https://golang.org/cl/4382044

Rewrite MOVB with less expensive
instruction when possible.

Suggested by atomic symbol.

benchmark                                        old ns/op    new ns/op    delta
crc32.BenchmarkCrc32KB                               13066         3942  -69.83%
crc64.BenchmarkCrc64KB                                8780         5949  -32.24%
lzw.BenchmarkDecoder1e4                             771224       636538  -17.46%
lzw.BenchmarkDecoder1e5                            7101218      6096634  -14.15%
lzw.BenchmarkDecoder1e6                           69762020     60789400  -12.86%
lzw.BenchmarkEncoder1e4                             707968       638812   -9.77%
lzw.BenchmarkEncoder1e5                            6567122      5965552   -9.16%
lzw.BenchmarkEncoder1e6                           65006000     58911680   -9.38%
utf8_test.BenchmarkRuneCountTenASCIIChars              166          165   -0.60%
utf8_test.BenchmarkRuneCountTenJapaneseChars           246          258   +4.88%
utf8_test.BenchmarkEncodeASCIIRune                      13           10  -23.08%
utf8_test.BenchmarkEncodeJapaneseRune                   37           16  -56.76%
utf8_test.BenchmarkDecodeASCIIRune                      23           21   -8.70%
utf8_test.BenchmarkDecodeJapaneseRune                   58           32  -44.83%

R=ken2
CC=golang-dev
https://golang.org/cl/4381045

Fixes #1670.

R=ken2
CC=golang-dev
https://golang.org/cl/4386045

R=rsc
CC=golang-dev
https://golang.org/cl/4271080

R=r
CC=golang-dev
https://golang.org/cl/4380043

R=ken2
CC=golang-dev, mikkel
https://golang.org/cl/4384048

Quiets the pop-up boxes on OS X.

R=bradfitzgo, r2
CC=golang-dev
https://golang.org/cl/4387042

In the current codereview, if a patch was written against
a version of a file that had subsequently been edited,
hg clpatch would fail, even if the patch and the edits were
in different parts of the file.  In this situation the reviewer
typically wrote back saying "please hg sync and hg mail
to update the patch".

This change rewrites the patch automatically, using the
same transformation that hg sync + hg mail would.

If the interim changes (since the patch was created)
affect the same line ranges as the patch, clpatch will
still refuse to apply it.  But this CL should make
of the trivial conflicts we see just go away.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/4377046

R=rsc, brainman, rh, r2
CC=golang-dev
https://golang.org/cl/4366045

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/4353043

R=gri
CC=golang-dev
https://golang.org/cl/4343047

  * add -diff command line option
  * use scoping information in refersTo, isPkgDot, isPtrPkgDot.
  * add new scoping-based helpers countUses, rewriteUses, assignsTo, isTopName.
  * rename rewrite to walk, add walkBeforeAfter.
  * add toy typechecker, a placeholder for go/types

R=gri
CC=golang-dev
https://golang.org/cl/4285053

Type is now an interface that implements all the possible type methods.
Instead of a type switch on a reflect.Type t, switch on t.Kind().
If a method is invoked on the wrong kind of type (for example,
calling t.Field(0) when t.Kind() != Struct), the call panics.

There is one method renaming: t.(*ChanType).Dir() is now t.ChanDir().

Value is now a struct value that implements all the possible value methods.
Instead of a type switch on a reflect.Value v, switch on v.Kind().
If a method is invoked on the wrong kind of value (for example,
calling t.Recv() when t.Kind() != Chan), the call panics.

Since Value is now a struct, not an interface, its zero value
cannot be compared to nil.  Instead of v != nil, use v.IsValid().
Instead of other uses of nil as a Value, use Value{}, the zero value.

Many methods have been renamed, most due to signature conflicts:

           OLD                          NEW

    v.(*ArrayValue).Elem             v.Index
    v.(*BoolValue).Get               v.Bool
    v.(*BoolValue).Set               v.SetBool
    v.(*ChanType).Dir                v.ChanDir
    v.(*ChanValue).Get               v.Pointer
    v.(*ComplexValue).Get            v.Complex
    v.(*ComplexValue).Overflow       v.OverflowComplex
    v.(*ComplexValue).Set            v.SetComplex
    v.(*FloatValue).Get              v.Float
    v.(*FloatValue).Overflow         v.OverflowFloat
    v.(*FloatValue).Set              v.SetFloat
    v.(*FuncValue).Get               v.Pointer
    v.(*InterfaceValue).Get          v.InterfaceData
    v.(*IntValue).Get                v.Int
    v.(*IntValue).Overflow           v.OverflowInt
    v.(*IntValue).Set                v.SetInt
    v.(*MapValue).Elem               v.MapIndex
    v.(*MapValue).Get                v.Pointer
    v.(*MapValue).Keys               v.MapKeys
    v.(*MapValue).SetElem            v.SetMapIndex
    v.(*PtrValue).Get                v.Pointer
    v.(*SliceValue).Elem             v.Index
    v.(*SliceValue).Get              v.Pointer
    v.(*StringValue).Get             v.String
    v.(*StringValue).Set             v.SetString
    v.(*UintValue).Get               v.Uint
    v.(*UintValue).Overflow          v.OverflowUint
    v.(*UintValue).Set               v.SetUint
    v.(*UnsafePointerValue).Get      v.Pointer
    v.(*UnsafePointerValue).Set      v.SetPointer

Part of the motivation for this change is to enable a more
efficient implementation of Value, one that does not allocate
memory during most operations.  To reduce the size of the CL,
this CL's implementation is a wrapper around the old API.
Later CLs will make the implementation more efficient without
changing the API.

Other CLs to be submitted at the same time as this one
add support for this change to gofix (4343047) and update
the Go source tree (4353043).

R=gri, iant, niemeyer, r, rog, gustavo, r2
CC=golang-dev
https://golang.org/cl/4281055

Rewrite only if we understood all the flags we saw.

R=r
CC=golang-dev
https://golang.org/cl/4376046

R=golang-dev, peterGo, rsc1
CC=Joe Poirier, golang-dev
https://golang.org/cl/4370048

R=rsc
CC=golang-dev
https://golang.org/cl/4369050

R=rsc
CC=golang-dev
https://golang.org/cl/4358043

This CL defines a new, more Go-like representation of
Go types (different structs for different types as
opposed to a single Type node). It also implements
an ast.Importer for object/archive files generated
by the gc compiler tool chain. Besides the individual
type structs, the main difference is the handling of
named types: In the old world, a named type had a
non-nil *Object pointer but otherwise looked no
different from other types. In this new model, named
types have their own representation types.Name. As
a result, resolving cycles is a bit simpler during
construction, at the cost of having to deal with
types.Name nodes explicitly later. It remains to be
seen if this is a good approach. Nevertheless, code
involving types reads more nicely and benefits from
full type checking. Also, the representation seems
to more closely match the spec wording.

Credits: The original version of the gc importer was
written by Evan Shaw (chickencha@gmail.com). The new
version in this CL is based largely on Evan's original
code but contains bug fixes, a few simplifications,
some restructuring, and was adjusted to use the
new type hierarchy. I have added a comprehensive test
that imports all packages found under $GOROOT/pkg (with
a 3s time-out to limit the run-time of the test). Run
gotest -v for details.

The original version of ExportData (exportdata.go) was
written by Russ Cox (rsc@golang.org). The current version
is returning the internal buffer positioned at the beginning
of the export data instead of printing the export data to
stdout.

With the new types package, the existing in-progress
typechecker package is deprecated. I will delete it
once all functionality has been brought over.

R=eds, rog, rsc
CC=golang-dev
https://golang.org/cl/4314054

R=rsc
CC=golang-dev
https://golang.org/cl/4373048

A codewalk through a simple program that illustrates several aspects of Go functions: function objects, higher-order functions, variadic functions, tail recursion, etc.  The example program simulates the game of Pig, a dice game with simple rules but a nontrivial solution.

R=adg, rsc, iant2, r
CC=golang-dev
https://golang.org/cl/4306045

R=golang-dev, rsc1
CC=golang-dev
https://golang.org/cl/4366043

R=golang-dev, rsc1
CC=golang-dev, vcc
https://golang.org/cl/4374044

Thanks to fhs.

R=golang-dev, r2
CC=ality, fhs, golang-dev
https://golang.org/cl/4375044

Fixes #1674.

R=ken2
CC=golang-dev
https://golang.org/cl/4368057

TBR=r
CC=golang-dev
https://golang.org/cl/4380042

R=r
CC=golang-dev
https://golang.org/cl/4386042

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/4368050

Fixes #1658.

R=rsc
CC=golang-dev
https://golang.org/cl/4344066

Fixes #1559.

R=rsc
CC=golang-dev, peterGo, rog
https://golang.org/cl/4356046

I love Python.  Write once, crash anywhere.

TBR=r
CC=golang-dev
https://golang.org/cl/4382043

Right now if a Go developer makes a patch on one machine
and then clpatches it onto another machine, changes
subsequently made to the description are kept only
locally, under the assumption that you are running
clpatch because someone else wrote the CL, so you
don't have permission to update the web.

This change makes clpatch discard the "this was a
clpatch" information from the metadata when you
clpatch your own CLs from one machine to another.

This should eliminate some confusion (for example
in CL 4314054) but will no doubt introduce other
confusion.

R=golang-dev, r2
CC=golang-dev
https://golang.org/cl/4387041