Fixes #18550

Change-Id: Ia08d0ef6964216fcc14fa63c2ba378d68daa2c02
Reviewed-on: https://go-review.googlesource.com/34917Reviewed-by: Chris Broadfoot <cbro@golang.org>

Rule 9 arguably doesn't make sense for IPv4 addresses, and so far it
has only caused problems (#13283, #18518). Disable it until we hear
from users that actually want/need it.

Fixes #18518.

Change-Id: I7b0dd75d03819cab8e0cd4c29f0c1dc8d2e9c179
Reviewed-on: https://go-review.googlesource.com/34914Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

CALLPART of STRUCTLIT did not check for incomplete initialization
of struct; modify PTRLIT treatment to force zeroing.

Test for structlit, believe this might have also failed for
arraylit.

Fixes #18410.

Change-Id: I511abf8ef850e300996d40568944665714efe1fc
Reviewed-on: https://go-review.googlesource.com/34622
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

Updates #18294.

Change-Id: Ib6b84243a15ed921cc8960e5fa355fd7594181e6
Reviewed-on: https://go-review.googlesource.com/34821Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

To implement the blocking of a select, a goroutine builds a list of
offers to communicate (pseudo-g's, aka sudog), one for each case,
queues them on the corresponding channels, and waits for another
goroutine to complete one of those cases and wake it up. Obviously it
is not OK for two other goroutines to complete multiple cases and both
wake the goroutine blocked in select. To make sure that only one
branch of the select is chosen, all the sudogs contain a pointer to a
shared (single) 'done uint32', which is atomically cas'ed by any
interested goroutines. The goroutine that wins the cas race gets to
wake up the select. A complication is that 'done uint32' is stored on
the stack of the goroutine running the select, and that stack can move
during the select due to stack growth or stack shrinking.

The relevant ordering to block and unblock in select is:

	1. Lock all channels.
	2. Create list of sudogs and queue sudogs on all channels.
	3. Switch to system stack, mark goroutine as asleep,
	   unlock all channels.
	4. Sleep until woken.
	5. Wake up on goroutine stack.
	6. Lock all channels.
	7. Dequeue sudogs from all channels.
	8. Free list of sudogs.
	9. Unlock all channels.

There are two kinds of stack moves: stack growth and stack shrinking.
Stack growth happens while the original goroutine is running.
Stack shrinking happens asynchronously, during garbage collection.

While a channel listing a sudog is locked by select in this process,
no other goroutine can attempt to complete communication on that
channel, because that other goroutine doesn't hold the lock and can't
find the sudog. If the stack moves while all the channel locks are
held or when the sudogs are not yet or no longer queued in the
channels, no problem, because no goroutine can get to the sudogs and
therefore to selectdone. We only need to worry about the stack (and
'done uint32') moving with the sudogs queued in unlocked channels.

Stack shrinking can happen any time the goroutine is stopped.
That code already acquires all the channel locks before doing the
stack move, so it avoids this problem.

Stack growth can happen essentially any time the original goroutine is
running on its own stack (not the system stack). In the first half of
the select, all the channels are locked before any sudogs are queued,
and the channels are not unlocked until the goroutine has stopped
executing on its own stack and is asleep, so that part is OK. In the
second half of the select, the goroutine wakes up on its own goroutine
stack and immediately locks all channels. But the actual call to lock
might grow the stack, before acquiring any locks. In that case, the
stack is moving with the sudogs queued in unlocked channels. Not good.
One goroutine has already won a cas on the old stack (that goroutine
woke up the selecting goroutine, moving it out of step 4), and the
fact that done = 1 now should prevent any other goroutines from
completing any other select cases. During the stack move, however,
sudog.selectdone is moved from pointing to the old done variable on
the old stack to a new memory location on the new stack. Another
goroutine might observe the moved pointer before the new memory
location has been initialized. If the new memory word happens to be
zero, that goroutine might win a cas on the new location, thinking it
can now complete the select (again). It will then complete a second
communication (reading from or writing to the goroutine stack
incorrectly) and then attempt to wake up the selecting goroutine,
which is already awake.

The scribbling over the goroutine stack unexpectedly is already bad,
but likely to go unnoticed, at least immediately. As for the second
wakeup, there are a variety of ways it might play out.

* The goroutine might not be asleep.
That will produce a runtime crash (throw) like in #17007:

	runtime: gp: gp=0xc0422dcb60, goid=2299, gp->atomicstatus=8
	runtime:  g:  g=0xa5cfe0, goid=0,  g->atomicstatus=0
	fatal error: bad g->status in ready

Here, atomicstatus=8 is copystack; the second, incorrect wakeup is
observing that the selecting goroutine is in state "Gcopystack"
instead of "Gwaiting".

* The goroutine might be sleeping in a send on a nil chan.
If it wakes up, it will crash with 'fatal error: unreachable'.

* The goroutine might be sleeping in a send on a non-nil chan.
If it wakes up, it will crash with 'fatal error: chansend:
spurious wakeup'.

* The goroutine might be sleeping in a receive on a nil chan.
If it wakes up, it will crash with 'fatal error: unreachable'.

* The goroutine might be sleeping in a receive on a non-nil chan.
If it wakes up, it will silently (incorrectly!) continue as if it
received a zero value from a closed channel, leaving a sudog queued on
the channel pointing at that zero vaue on the goroutine's stack; that
space will be reused as the goroutine executes, and when some other
goroutine finally completes the receive, it will do a stray write into
the goroutine's stack memory, which may cause problems. Then it will
attempt the real wakeup of the goroutine, leading recursively to any
of the cases in this list.

* The goroutine might have been running a select in a finalizer
(I hope not!) and might now be sleeping waiting for more things to
finalize. If it wakes up, as long as it goes back to sleep quickly
(before the real GC code tries to wake it), the spurious wakeup does
no harm (but the stack was still scribbled on).

* The goroutine might be sleeping in gcParkAssist.
If it wakes up, that will let the goroutine continue executing a bit
earlier than we would have liked. Eventually the GC will attempt the
real wakeup of the goroutine, leading recursively to any of the cases
in this list.

* The goroutine cannot be sleeping in bgsweep, because the background
sweepers never use select.

* The goroutine might be sleeping in netpollblock.
If it wakes up, it will crash with 'fatal error: netpollblock:
corrupted state'.

* The goroutine might be sleeping in main as another thread crashes.
If it wakes up, it will exit(0) instead of letting the other thread
crash with a non-zero exit status.

* The goroutine cannot be sleeping in forcegchelper,
because forcegchelper never uses select.

* The goroutine might be sleeping in an empty select - select {}.
If it wakes up, it will return to the next line in the program!

* The goroutine might be sleeping in a non-empty select (again).
In this case, it will wake up spuriously, with gp.param == nil (no
reason for wakeup), but that was fortuitously overloaded for handling
wakeup due to a closing channel and the way it is handled is to rerun
the select, which (accidentally) handles the spurious wakeup
correctly:

	if cas == nil {
		// This can happen if we were woken up by a close().
		// TODO: figure that out explicitly so we don't need this loop.
		goto loop
	}

Before looping, it will dequeue all the sudogs on all the channels
involved, so that no other goroutine will attempt to wake it.
Since the goroutine was blocked in select before, being blocked in
select again when the spurious wakeup arrives may be quite likely.
In this case, the spurious wakeup does no harm (but the stack was
still scribbled on).

* The goroutine might be sleeping in semacquire (mutex slow path).
If it wakes up, that is taken as a signal to try for the semaphore
again, not a signal that the semaphore is now held, but the next
iteration around the loop will queue the sudog a second time, causing
a cycle in the wakeup list for the given address. If that sudog is the
only one in the list, when it is eventually dequeued, it will
(due to the precise way the code is written) leave the sudog on the
queue inactive with the sudog broken. But the sudog will also be in
the free list, and that will eventually cause confusion.

* The goroutine might be sleeping in notifyListWait, for sync.Cond.
If it wakes up, (*Cond).Wait returns. The docs say "Unlike in other
systems, Wait cannot return unless awoken by Broadcast or Signal,"
so the spurious wakeup is incorrect behavior, but most callers do not
depend on that fact. Eventually the condition will happen, attempting
the real wakeup of the goroutine and leading recursively to any of the
cases in this list.

* The goroutine might be sleeping in timeSleep aka time.Sleep.
If it wakes up, it will continue running, leaving a timer ticking.
When that time bomb goes off, it will try to ready the goroutine
again, leading to any one of the cases in this list.

* The goroutine cannot be sleeping in timerproc,
because timerproc never uses select.

* The goroutine might be sleeping in ReadTrace.
If it wakes up, it will print 'runtime: spurious wakeup of trace
reader' and return nil. All future calls to ReadTrace will print
'runtime: ReadTrace called from multiple goroutines simultaneously'.
Eventually, when trace data is available, a true wakeup will be
attempted, leading to any one of the cases in this list.

None of these fatal errors appear in any of the trybot or dashboard
logs. The 'bad g->status in ready' that happens if the goroutine is
running (the most likely scenario anyway) has happened once on the
dashboard and eight times in trybot logs. Of the eight, five were
atomicstatus=8 during net/http tests, so almost certainly this bug.
The other three were atomicstatus=2, all near code in select,
but in a draft CL by Dmitry that was rewriting select and may or may
not have had its own bugs.

This bug has existed since Go 1.4. Until then the select code was
implemented in C, 'done uint32' was a C stack variable 'uint32 done',
and C stacks never moved. I believe it has become more common recently
because of Brad's work to run more and more tests in net/http in
parallel, which lengthens race windows.

The fix is to run step 6 on the system stack,
avoiding possibility of stack growth.

Fixes #17007 and possibly other mysterious failures.

Change-Id: I9d6575a51ac96ae9d67ec24da670426a4a45a317
Reviewed-on: https://go-review.googlesource.com/34835
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Austin Clements <austin@google.com>

This adds high-level descriptions of the scheduler structures, the
user and system stacks, error handling, and synchronization.

Change-Id: I1eed97c6dd4a6e3d351279e967b11c6e64898356
Reviewed-on: https://go-review.googlesource.com/34290Reviewed-by: Rick Hudson <rlh@golang.org>

The comment describing the overall GC algorithm at the top of mgc.go
has gotten woefully out-of-date (and was possibly never
correct/complete). Update it to reflect the current workings of the
GC and the set of phases that we now divide it into.

Change-Id: I02143c0ebefe9d4cd7753349dab8045f0973bf95
Reviewed-on: https://go-review.googlesource.com/34711Reviewed-by: Rick Hudson <rlh@golang.org>

If one of the c.Get(ts.URL) results in an error, the child goroutine
calls t.Errorf, but the test goroutine gets stuck waiting for <-gotReqCh,
so the test hangs and the program is eventually killed (after 10 minutes!).
Whatever might have been printed to t.Errorf is never seen.
Adjust test so that the test fails cleanly in this case.

Still trying to debug why c.Get might fail.
It seems to have something to do with occasional connection
failures on macOS Sierra.

Change-Id: Ia797787bd51ea7cd6deb1192aec89c331c4f2c48
Reviewed-on: https://go-review.googlesource.com/34836
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Currently, the check for legal pointers in stack copying uses
_PageSize (8K) as the minimum legal pointer. By default, Linux won't
let you map under 64K, but

1) it's less clear what other OSes allow or will allow in the future;

2) while mapping the first page is a terrible idea, mapping anywhere
above that is arguably more justifiable;

3) the compiler only assumes the first physical page (4K) is never
mapped.

Make the runtime consistent with the compiler and more robust by
changing the bad pointer check to use 4K as the minimum legal pointer.

This came out of discussions on CLs 34663 and 34719.

Change-Id: Idf721a788bd9699fb348f47bdd083cf8fa8bd3e5
Reviewed-on: https://go-review.googlesource.com/34890
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>

Change-Id: I1c2e17b25ca91be37a18c47e70678c3753070fb8
Reviewed-on: https://go-review.googlesource.com/34827Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>

We cannot assume that the platform running documentation service is
the target platform.

Change-Id: I241ed6f8778169faac9ef49e11dcd40f7422cccc
Reviewed-on: https://go-review.googlesource.com/34750
Run-TryBot: Mikio Hara <mikioh.mikioh@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

Fixes #18392.

Avoid nil dereferencing n.Right when dealing with non-existent
self referenced interface methods e.g.
type A interface{
  Fn(A.Fn)
}

Instead, infer the symbol name from n.Sym itself.

Change-Id: I60d5f8988e7318693e5c8da031285d8d7347b771
Reviewed-on: https://go-review.googlesource.com/34817
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

Change-Id: I184c86edaaaa71c26bc7360c8b995015f30fe137
Reviewed-on: https://go-review.googlesource.com/34819Reviewed-by: Russ Cox <rsc@golang.org>

Be consistent on whether the http proxy environment variables are
respected regardless of whether -insecure is used.

Updates #18519

Change-Id: Ib157eaacfd342dd3bfcd03e64da18c98c609cae3
Reviewed-on: https://go-review.googlesource.com/34818
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

This change uses runtime.support_bmi2 as an additional condition
to examine the usability of AVX2 version algorithm, fixes
the crash on the platfrom which supports AVX2 but not support BMI2.

Fixes #18512

Change-Id: I408c0844ae2eb242dacf70cb9e8cec1b8f3bd941
Reviewed-on: https://go-review.googlesource.com/34851Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

The existing implementations on AMD64 only detects AVX2 usability,
when they also contains BMI (bit-manipulation instructions).
These instructions crash the running program as 'unknown instructions'
on the architecture, e.g. i3-4000M, which supports AVX2 but not
support BMI.

This change added the detections for BMI1 and BMI2 to AMD64 runtime with
two flags as the result, `support_bmi1` and `support_bmi2`,
in runtime/runtime2.go. It also completed the condition to run AVX2 version
in packages crypto/sha1 and crypto/sha256.

Fixes #18512

Change-Id: I917bf0de365237740999de3e049d2e8f2a4385ad
Reviewed-on: https://go-review.googlesource.com/34850Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

When I wrote the lines

	bin/
	pkg/

I was trying to match just the top-level bin and pkg directories, and I put the
final slash in because 'git help gitignore' says:

       o   If the pattern does not contain a slash /, Git treats it as a shell
           glob pattern and checks for a match against the pathname relative
           to the location of the .gitignore file (relative to the toplevel of
           the work tree if not from a .gitignore file).

       o   Otherwise, Git treats the pattern as a shell glob suitable for
           consumption by fnmatch(3) with the FNM_PATHNAME flag: wildcards in
           the pattern will not match a / in the pathname. For example,
           "Documentation/*.html" matches "Documentation/git.html" but not
           "Documentation/ppc/ppc.html" or
           "tools/perf/Documentation/perf.html".

Putting a trailing slash was my way of opting in to the "rooted path" semantics
without looking different from the surrounding rooted paths like "src/go/build/zcgo.go".

But HA HA GIT FOOLED YOU! above those two bullets the docs say:

       o   If the pattern ends with a slash, it is removed for the purpose of
           the following description, ...

Change all the patterns to use a leading slash for "rooted" behavior.

This bit me earlier today because I had a perfectly reasonable source
code directory go/src/cmd/go/testdata/src/empty/pkg that was
not added by 'git add empty'.

Change-Id: I6f8685b3c5be22029c33de9ccd735487089a1c03
Reviewed-on: https://go-review.googlesource.com/34832Reviewed-by: Ian Lance Taylor <iant@golang.org>

Fixes #18500

Change-Id: I4dddd1b99aecf86b9431b0c14f452152dff9b95a
Reviewed-on: https://go-review.googlesource.com/34816Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Fixes #18494

Change-Id: I8a190acae6d5f1d20d4e4e4547d84e10e8a7fe68
Reviewed-on: https://go-review.googlesource.com/34793Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>

Fixes #18506

Change-Id: I6b0b107296311178938609e878e1ef47a30a463f
Reviewed-on: https://go-review.googlesource.com/34814Reviewed-by: Ian Lance Taylor <iant@golang.org>

Fixes #18447

Change-Id: I5d60c3632a5ce625d3bac9d85533ce689e301707
Reviewed-on: https://go-review.googlesource.com/34813Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

No test because in practice these errors never occur.

Change-Id: I11c77893ae931fc621c98920cba656790d18ed93
Reviewed-on: https://go-review.googlesource.com/34811
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Fixes #18486.

Change-Id: I359dc4169e04b4123bd41679ea939b06fa754ac2
Reviewed-on: https://go-review.googlesource.com/34830
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

For #18496.

Change-Id: I50ced7c9f0fe5d9c627eef1f59a7f73be742e04c
Reviewed-on: https://go-review.googlesource.com/34831
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Otherwise 64k pages don't map correctly.

Fixes #18408.

Change-Id: I85f56682531566d1ff5c655640cd58509514aee8
Reviewed-on: https://go-review.googlesource.com/34629
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>

Android on ChromeOS uses a restrictive seccomp filter that blocks
sched_getaffinity, leading this code to index a slice by -errno.

Change-Id: Iec09a4f79dfbc17884e24f39bcfdad305de75b37
Reviewed-on: https://go-review.googlesource.com/34794Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>

Given
	var t struct{ lock sync.Mutex }
	var fntab []func(t)
	f(a(), b(&t), c(), fntab[0](t))

Before:
	function call copies lock value: struct{lock sync.Mutex} contains sync.Mutex

After:
	call of fntab[0] copies lock value: struct{lock sync.Mutex} contains sync.Mutex

This will make diagnosis easier when there are multiple function calls per line.

Change-Id: I9881713c5671b847b84a0df0115f57e7cba17d72
Reviewed-on: https://go-review.googlesource.com/34730Reviewed-by: Ian Lance Taylor <iant@golang.org>

Change-Id: Ia97d770cd942a49a34c733643ced7490fc31c736
Reviewed-on: https://go-review.googlesource.com/34795
Run-TryBot: Michael Munday <munday@ca.ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

Change-Id: I9e37aece5ace374e89bee70962a19f76ae3266bc
Reviewed-on: https://go-review.googlesource.com/34646
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Fixes misc/cgo/testsigfwd, enabled for mips{,le} with the next commit
(https://golang.org/cl/34646).

Change-Id: I2bec894b0492fd4d84dd73a4faa19eafca760107
Reviewed-on: https://go-review.googlesource.com/34645Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Clean up the phrasing a little bit, make the comment fit in 80
characters, and fix the spelling of "guard."

Change-Id: I688a3e760b8d67ea83830635f64dff04dd9a5911
Reviewed-on: https://go-review.googlesource.com/34792Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Previously Tx.done was being set in close, but in a Tx
rollback and Commit are the real closing methods,
and Tx.close is just a helper common to both. Prior to this
change a multiple rollback statements could be called, one
would enter close and begin closing it while the other was
still in rollback breaking it. Fix that by setting done
in rollback and Commit, not in Tx.close.

Fixes #18429

Change-Id: Ie274f60c2aa6a4a5aa38e55109c05ea9d4fe0223
Reviewed-on: https://go-review.googlesource.com/34716Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

It doesn't work if the package name includes a '.' or a non-ASCII
character (or '%', '"', or a control character).  See #16710 and CL 31970.

Update #18246.

Change-Id: I1487f462a3dc7b0016fce3aa1ea6239b226e6e39
Reviewed-on: https://go-review.googlesource.com/34791Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Updates http2 to x/net/http2 git rev 8fd7f25 for:

    http2: clear WriteTimeout in Server
    https://golang.org/cl/34724

And un-skip the new test. (The new test is a slow test, anyway, so
won't affect builders or all.bash, but I verified it now passes.)

Updates #18437

Change-Id: Ia91ae702edfd23747a9d6b61da284a5a957bfed3
Reviewed-on: https://go-review.googlesource.com/34729
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
Reviewed-by: Kale B <kale@lemnisys.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Current handling of WriteTimeout for http2 does not
extend the timeout on new streams. Disable the WriteTimeout
in http2 for 1.8 release.

Updates #18437

Change-Id: I20480432ab176f115464434645defb56ebeb6ece
Reviewed-on: https://go-review.googlesource.com/34723Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Avoid potential race conditions by clarifying to implemntors of the
ReverseProxy interface, the lifetime of provided http.Request structs.

Fixes #18456
Change-Id: I46aa60322226ecc3a0d30fa1ef108e504171957a
Reviewed-on: https://go-review.googlesource.com/34720Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Remove unneeded second colon.

Remove unneeded space at the beginning of a line (before a tab).

Regenerate alldocs.go with mkalldocs.sh.

Updates https://golang.org/cl/28783.
Updates https://golang.org/cl/29650.
Fixes #18448.

Change-Id: I1830136a2b760827d4cec565744807a0fd147584
Reviewed-on: https://go-review.googlesource.com/34718Reviewed-by: Rob Pike <r@golang.org>

Fixes #6772.

Lock-in test for invalid range loop: repeated variables in range declaration.

Change-Id: I37dd8b1cd7279abe7810deaf8a5d485c5c3b73ca
Reviewed-on: https://go-review.googlesource.com/34714Reviewed-by: Keith Randall <khr@golang.org>

This is a follow-up for https://golang.org/cl/24340.

Updates #14664.
Fixes #18374.

Change-Id: I2831556a9014d30ec70d5f91943d18c33db5b390
Reviewed-on: https://go-review.googlesource.com/34630Reviewed-by: Rob Pike <r@golang.org>
Run-TryBot: Rob Pike <r@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Change-Id: Iae8cdcd84e9b5f5d7c698abc6da3fc2af0ef839a
Reviewed-on: https://go-review.googlesource.com/34710Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>