gccgo_install.html: the 4.9 release series supports Go 1.2

LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://codereview.appspot.com/163760043
spec: minimal documention of unsafe.Pointer conversions

Per suggestion from rsc as a result of the dicussion of
(abandoned) CL 153110044.

Fixes issue 7192.

LGTM=r, rsc, iant
R=r, rsc, iant, ken
CC=golang-codereviews
https://codereview.appspot.com/163050043
encoding/csv: for Postgres, unquote empty strings, quote \.

In theory both of these lines encode the same three fields:

        a,,c
        a,"",c

However, Postgres defines that when importing CSV, the unquoted
version is treated as NULL (missing), while the quoted version is
treated as a string value (empty string). If the middle field is supposed to
be an integer value, the first line can be imported (NULL is okay), but
the second line cannot (empty string is not).

Postgres's import command (COPY FROM) has an option to force
the unquoted empty to be interpreted as a string but it does not
have an option to force the quoted empty to be interpreted as a NULL.

From http://www.postgresql.org/docs/9.0/static/sql-copy.html:

        The CSV format has no standard way to distinguish a NULL
        value from an empty string. PostgreSQL's COPY handles this
        by quoting. A NULL is output as the NULL parameter string
        and is not quoted, while a non-NULL value matching the NULL
        parameter string is quoted. For example, with the default
        settings, a NULL is written as an unquoted empty string,
        while an empty string data value is written with double
        quotes (""). Reading values follows similar rules. You can
        use FORCE_NOT_NULL to prevent NULL input comparisons for
        specific columns.

Therefore printing the unquoted empty is more flexible for
imports into Postgres than printing the quoted empty.

In addition to making the output more useful with Postgres, not
quoting empty strings makes the output smaller and easier to read.
It also matches the behavior of Microsoft Excel and Google Drive.

Since we are here and making concessions for Postgres, handle this
case too (again quoting the Postgres docs):

        Because backslash is not a special character in the CSV
        format, \., the end-of-data marker, could also appear as a
        data value. To avoid any misinterpretation, a \. data value
        appearing as a lone entry on a line is automatically quoted
        on output, and on input, if quoted, is not interpreted as
        the end-of-data marker. If you are loading a file created by
        another application that has a single unquoted column and
        might have a value of \., you might need to quote that value
        in the input file.

Fixes issue 7586.

LGTM=bradfitz
R=bradfitz
CC=golang-codereviews
https://codereview.appspot.com/164760043
doc/go1.4: encoding/csv

CC=golang-codereviews
https://codereview.appspot.com/162140043
cmd/gc: synthesize zeroed value for non-assignment context

CL 157910047 introduced code to turn a node representing
a zeroed composite literal into N, the nil Node* pointer
(which represents any zero, not the Go literal nil).

That's great for assignments like x = T{}, but it doesn't work
when T{} is used in a value context like T{}.v or x == T{}.
Fix those.

Should have no effect on performance; confirmed.
The deltas below are noise (compare ns/op):

benchmark                          old ns/op      new ns/op      delta
BenchmarkBinaryTree17              2902919192     2915228424     +0.42%
BenchmarkFannkuch11                2597417605     2630363685     +1.27%
BenchmarkFmtFprintfEmpty           73.7           74.8           +1.49%
BenchmarkFmtFprintfString          196            199            +1.53%
BenchmarkFmtFprintfInt             213            217            +1.88%
BenchmarkFmtFprintfIntInt          336            356            +5.95%
BenchmarkFmtFprintfPrefixedInt     289            294            +1.73%
BenchmarkFmtFprintfFloat           415            416            +0.24%
BenchmarkFmtManyArgs               1281           1271           -0.78%
BenchmarkGobDecode                 10271734       10307978       +0.35%
BenchmarkGobEncode                 8985021        9079442        +1.05%
BenchmarkGzip                      410233227      412266944      +0.50%
BenchmarkGunzip                    102114554      103272443      +1.13%
BenchmarkHTTPClientServer          45297          44993          -0.67%
BenchmarkJSONEncode                19499741       19498489       -0.01%
BenchmarkJSONDecode                76436733       74247497       -2.86%
BenchmarkMandelbrot200             4273814        4307292        +0.78%
BenchmarkGoParse                   4024594        4028937        +0.11%
BenchmarkRegexpMatchEasy0_32       131            135            +3.05%
BenchmarkRegexpMatchEasy0_1K       328            333            +1.52%
BenchmarkRegexpMatchEasy1_32       115            117            +1.74%
BenchmarkRegexpMatchEasy1_1K       931            948            +1.83%
BenchmarkRegexpMatchMedium_32      216            217            +0.46%
BenchmarkRegexpMatchMedium_1K      72669          72857          +0.26%
BenchmarkRegexpMatchHard_32        3818           3809           -0.24%
BenchmarkRegexpMatchHard_1K        121398         121945         +0.45%
BenchmarkRevcomp                   613996550      615145436      +0.19%
BenchmarkTemplate                  93678525       93267391       -0.44%
BenchmarkTimeParse                 414            411            -0.72%
BenchmarkTimeFormat                396            399            +0.76%


Fixes issue 8947.

LGTM=r
R=r, dave
CC=golang-codereviews
https://codereview.appspot.com/162130043
net/http/pprof: run GC for /debug/pprof/heap?gc=1

We force runtime.GC before WriteHeapProfile with -test.heapprofile.
Make it possible to do the same with the HTTP interface.

Some servers only run a GC every few minutes.
On such servers, the heap profile will be a few minutes stale,
which may be too old to be useful.

Requested by private mail.

LGTM=dvyukov
R=dvyukov
CC=golang-codereviews
https://codereview.appspot.com/161990043
unsafe: document that unsafe programs are not protected
The compatibility guideline needs to be clear about this even
though it means adding a clause that was not there from the
beginning. It has always been understood, so this isn't really
a change in policy, just in its expression.

LGTM=bradfitz, gri, rsc
R=golang-codereviews, bradfitz, gri, rsc
CC=golang-codereviews
https://codereview.appspot.com/162060043
doc/go1.4.txt: unsafe is outside go1 compatibility guarantees

CC=golang-codereviews
https://codereview.appspot.com/164770043
cmd/go: add bzr support for vcs root checking

Complements the logic introduced in CL 147170043.

LGTM=rsc
R=rsc, gustavo
CC=golang-codereviews
https://codereview.appspot.com/147240043
cmd/go: pass $CGO_LDFLAGS to linker with the "gccgo" toolchain.

LGTM=iant
R=iant, minux
CC=golang-codereviews, golang-dev
https://codereview.appspot.com/157460043

Committer: Ian Lance Taylor <iant@golang.org>
doc/go_faq.html: fix a couple of nits
Wrong article, one stylistic point that bothers someone (but not me).

LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://codereview.appspot.com/156680043
misc/makerelease/windows: fix 404 help URL in installer

ARPHELPLINK yields 404; update the URL.

While here, also prefix the ARPREADME and ARPURLINFOABOUT URL's with the HTTP scheme to make 'em clickable links in the Add or Remove Programs listing.

LGTM=adg
R=golang-codereviews
CC=adg, golang-codereviews
https://codereview.appspot.com/154580045

Committer: Andrew Gerrand <adg@golang.org>
net: if a DNS lookup times out, forget that it is in flight

Before this CL, if the system resolver does a very slow DNS
lookup for a particular host, all subsequent requests for that
host will hang waiting for that lookup to complete.  That is
more or less expected when Dial is called with no deadline.
When Dial has a deadline, though, we can accumulate a large
number of goroutines waiting for that slow DNS lookup.  Try to
avoid this problem by restarting the DNS lookup when it is
redone after a deadline is passed.

This CL also avoids creating an extra goroutine purely to
handle the deadline.

No test because we would have to simulate a slow DNS lookup
followed by a fast DNS lookup.

Fixes issue 8602.

LGTM=bradfitz
R=bradfitz, mikioh.mikioh
CC=golang-codereviews, r, rsc
https://codereview.appspot.com/154610044
runtime: fix endianness assumption when decoding ftab

The ftab ends with a half functab record consisting only of
the 'entry' field followed by a uint32 giving the offset of
the next table.  Previously, symtabinit assumed it could read
this uint32 as a uintptr.  Since this is unsafe on big endian,
explicitly read the offset as a uint32.

LGTM=rsc
R=rsc
CC=golang-codereviews
https://codereview.appspot.com/157660043
[dev.power64] all: merge default into dev.power64

LGTM=rsc
R=rsc
CC=golang-codereviews
https://codereview.appspot.com/164110043
[dev.power64] liblink: fix lost branch target

A recent commit lost the branch target in the really-big-stack
case of splitstack, causing an infinite loop stack preempt
case.  Revive the branch target.

LGTM=rsc
R=rsc
CC=golang-codereviews
https://codereview.appspot.com/157790044
[dev.power64] runtime: power64 fixes and ports of changes

Fix include paths that got moved in the great pkg/ rename.  Add
missing runtime/arch_* files for power64.  Port changes that
happened on default since branching to
runtime/{asm,atomic,sys_linux}_power64x.s (precise stacks,
calling convention change, various new and deleted functions.
Port struct renaming and fix some bugs in
runtime/defs_linux_power64.h.

LGTM=rsc
R=rsc, dave
CC=golang-codereviews
https://codereview.appspot.com/161450043