Motivations:
 - Simpler UI. Previous API proved a bit awkward for practical purposes.
 - Iter is often used in cases where one want to be able to bail out early.
   The old implementaton had too much look-ahead to be efficient.
Disadvantages:
 - ASCII performance is bad. This is unavoidable for tiny iterations.
   Example is included to show how to work around this.

Description:
Iter now iterates per boundary/segment. It returns a slice of bytes that
either points to the input bytes, the internal decomposition strings,
or the small internal buffer that each iterator has. In many cases, copying
bytes is avoided.
The method Seek was added to support jumping around the input without
having to reinitialize.

Details:
 - Table adjustments: some decompositions exist of multiple segments.
   Decompositions that are of this type are now marked so that Iter can
   handle them separately.
 - The old iterator had a different next function for different normal forms
   that was assigned to a function pointer called by Next.
   The new iterator uses this mechanism to switch between different modes
   for handling different type of input as well.  This greatly improves
   performance for Hangul and ASCII. It is also used for multi-segment
   decompositions.
 - input is now a struct of sting and []byte, instead of an interface.
   This simplifies optimizing the ASCII case.

R=rsc
CC=golang-dev
https://golang.org/cl/6873072

the need to decompose characters for the majority of cases.  This considerably
speeds up collation while increasing the table size minimally.

To detect non-normalized strings, rather than relying on exp/norm, the table
now includes CCC information. The inclusion of this information does not
increase table size.

DETAILS
 - Raw collation elements are now a struct that includes the CCC, rather
   than a slice of ints.
 - Builder now ensures that NFD and NFC counterparts are included in the table.
   This also fixes a bug for Korean which is responsible for most of the growth
   of the table size.
 - As there is no more normalization step, code should now handle both strings
   and byte slices as input. Introduced source type to facilitate this.

NOTES
 - This change does not handle normalization correctly entirely for contractions.
   This causes a few failures with the regtest. table_test.go contains a few
   uncommented tests that can be enabled once this is fixed.  The easiest is to
   fix this once we have the new norm.Iter.
 - Removed a test cases in table_test that covers cases that are now guaranteed
   to not exist.

R=rsc, mpvl
CC=golang-dev
https://golang.org/cl/6971044

Currently it silently "succeeds" saying that it run 0 tests
if there are compilations errors.
With this change it fails and outputs the compilation error.

R=golang-dev, remyoudompheng
CC=golang-dev
https://golang.org/cl/7002058

Fixes #4578.

R=dvyukov, golang-dev
CC=golang-dev
https://golang.org/cl/7005050

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/7000045

NO_PROXY="example.com" should match "foo.example.com", just
the same as NO_PROXY=".example.com".  This is what curl and
Python do.

Fixes #4574

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/7005049

Not programming in Go anymore:
have to clear fields in local variables.

R=ken2
CC=golang-dev
https://golang.org/cl/7002053

Fixes #4070.

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/7004050

Before this CL, defining the variable worked fine, but then when
the implicit package-level init func was created, that caused a
name collision and a confusing error about the redeclaration.

Also add a test for issue 3705 (func init() needs body).

Fixes #4517.

R=ken2
CC=golang-dev
https://golang.org/cl/7008045

R=remyoudompheng
CC=golang-dev
https://golang.org/cl/7002052

An error during the compilation can be more precise
than an error at link time.

For 'func init', the error happens always: you can't forward
declare an init func because the name gets mangled.

For other funcs, the error happens only with the special
(and never used by hand) -= flag, which tells 6g the
package is pure go.

The go command now passes -= for pure Go packages.

Fixes #3705.

R=ken2
CC=golang-dev
https://golang.org/cl/6996054

Ordinary variable load was assumed to be not worth saving,
but not if one of the function calls later might change
its value.

Fixes #4313.

R=ken2
CC=golang-dev
https://golang.org/cl/6997047

The array skips the first TOKSTART entries.

Fixes #4410.

R=golang-dev, ken2, ken
CC=golang-dev
https://golang.org/cl/6999054

Fixes #3996.

R=ken2
CC=golang-dev
https://golang.org/cl/7001052

When we release memory to the OS, if the OS doesn't want us
to release it (for example, because the program executed
mlockall(MCL_FUTURE)), madvise will fail. Ignore the failure
instead of crashing.

Fixes #3435.

R=ken2
CC=golang-dev
https://golang.org/cl/6998052

benchmark             old ns/op    new ns/op    delta
BenchmarkDefer              165          113  -31.52%
BenchmarkDefer10            155          103  -33.55%
BenchmarkDeferMany          216          158  -26.85%

benchmark            old allocs   new allocs    delta
BenchmarkDefer                1            0  -100.00%
BenchmarkDefer10              1            0  -100.00%
BenchmarkDeferMany            1            0  -100.00%

benchmark             old bytes    new bytes    delta
BenchmarkDefer               64            0  -100.00%
BenchmarkDefer10             64            0  -100.00%
BenchmarkDeferMany           64           66    3.12%

Fixes #2364.

R=ken2
CC=golang-dev
https://golang.org/cl/7001051

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/6971048

Close the read side of the pipe.
Fixes #4551.

R=rsc
CC=golang-dev
https://golang.org/cl/6962049

Fixes #3887.

R=golang-dev, daniel.morsing, remyoudompheng, rsc
CC=golang-dev
https://golang.org/cl/6997045

Fixes #4581.

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/7000052

Any flag.Value that has an IsBoolFlag method that returns true
will be treated as a bool flag type during parsing.

Fixes #4262.

R=bradfitz, rsc
CC=golang-dev
https://golang.org/cl/6944064

The patch makes the compile user an ordinary package-local
symbol for the name of embedded fields of builtin type.

This is incompatible with the fix delivered for issue 2687
(revision 3c060add43fb) but fixes it in a different way, because
the explicit symbol on the field makes the typechecker able to
find it in lookdot.

Fixes #3552.

R=lvd, rsc, daniel.morsing
CC=golang-dev
https://golang.org/cl/6866047

The typechecking code was doing an extra, unnecessary
indirection.

Fixes #4458.

R=golang-dev, daniel.morsing, rsc
CC=golang-dev
https://golang.org/cl/6998051

Fixes #4470.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/6949073

Replacement for GOEXPERIMENT=zerostack, easier to use.
Does not require a separate toolchain.

R=ken2
CC=golang-dev
https://golang.org/cl/6996051

remove zerostack compiler experiment; will do at link time instead

««« original CL description
cmd/gc: add GOEXPERIMENT=zerostack to clear stack on function entry

This is expensive but it might be useful in cases where
people are suffering from false positives during garbage
collection and are willing to trade the CPU time for getting
rid of the false positives.

On the other hand it only eliminates false positives caused
by other function calls, not false positives caused by dead
temporaries stored in the current function call.

The 5g/6g/8g changes were pulled out of the history, from
the last time we needed to do this (to work around a goto bug).
The code in go.h, lex.c, pgen.c is new but tiny.

R=ken2
CC=golang-dev
https://golang.org/cl/6938073
»»»

R=ken2
CC=golang-dev
https://golang.org/cl/7002051

When using subexpressions ($1) as replacements, when they either don't exist or values weren't found causes a panic.
This patch ensures that the match location isn't -1, to prevent out of bounds errors.
Fixes #3816.

R=franciscossouza, rsc
CC=golang-dev
https://golang.org/cl/6931049

Generated by addca.

R=gobot
CC=golang-dev
https://golang.org/cl/7007051

EDE2 is a rare DES mode that can be implemented with crypto/des, but
it's somewhat non-obvious so this CL adds an example of doing so.

Fixes #3537.

R=golang-dev, adg
CC=golang-dev
https://golang.org/cl/6721056

Fixes #4579.

R=golang-dev, minux.ma
CC=golang-dev
https://golang.org/cl/7000051

Fixes #4562.

R=ken2
CC=golang-dev
https://golang.org/cl/7008044

Fixes #3559.

This makes Marshal handle fields marked ",any" instead of ignoring
them. That makes Marshal more symmetrical with Unmarshal, which seems
to have been a design goal.

Note some test cases were changed, because this patch changes
marshalling behavior. I think the previous behavior was buggy, but
there's still a backward-compatibility question to consider.

R=rsc
CC=golang-dev, n13m3y3r
https://golang.org/cl/6938068

R=golang-dev, minux.ma
CC=golang-dev
https://golang.org/cl/7003049

Also restore the smallintconst case for binary ops.

Fixes #3835.

R=daniel.morsing, rsc
CC=golang-dev
https://golang.org/cl/6999043

Most benchmarks are within the 3% margin of error. This code path is quite common in the fmt package.

linux/arm, Freescale iMX.53 (cortex-a8)

fmt:
benchmark                      old ns/op    new ns/op    delta
BenchmarkSprintfEmpty                925          785  -15.14%
BenchmarkSprintfString              5050         5039   -0.22%
BenchmarkSprintfInt                 4425         4406   -0.43%
BenchmarkSprintfIntInt              5802         5762   -0.69%
BenchmarkSprintfPrefixedInt         7029         6541   -6.94%
BenchmarkSprintfFloat              10278        10083   -1.90%
BenchmarkManyArgs                  18558        17606   -5.13%
BenchmarkScanInts               15592690     15415360   -1.14%
BenchmarkScanRecursiveInt       25155020     25050900   -0.41%

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/6921056

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/6996046

Taken from upstream pprof.

Fixes #4564.

R=golang-dev, minux.ma
CC=golang-dev
https://golang.org/cl/6952045

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/6997043

Fixes #4557.

R=dave, rsc
CC=golang-dev
https://golang.org/cl/6946078

This disables checks for limited address space
and unlimited stack. They are not required for Go.
Fixes #4577.

R=golang-dev, iant
CC=golang-dev, kamil.kisiel, minux.ma
https://golang.org/cl/7003045