On Go 1.11.x, if one ran 'go build' on a main package within a module,
while a needed vcs program like git was missing, a confusing error would
show up:

	build testmod: cannot find module for path rsc.io/quote

The error should instead point at the source of the problem, which is
the missing vcs program. Thankfully, Go 1.12 doesn't have this bug, even
though it doesn't seem like the bug was fixed directly and
intentionally.

To ensure that this particular edge case isn't broken again, add a
regression test. Piggyback on mod_vcs_missing, since it already requires
a missing vcs program and network access.

I double-checked that Go 1.11 fails this test via /usr/bin/go, which is
1.11.3 on my system:

	$ PATH=~/tip/bin go test -v -run Script/mod_vcs_missing
	[...]
	> exec /usr/bin/go build
	[stderr]
	build m: cannot find module for path launchpad.net/gocheck

Fixes #28948.

Change-Id: Iff1bcf77d9f7c11d15935cb87d6f58d7981d33d2
Reviewed-on: https://go-review.googlesource.com/c/155537
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>

This appears to have been an oversight and/or
left over from development.

Setting the genfile means that extra sanity
checks are executed when regenerating SSA files.
They already pass.

Change-Id: Icc01ecf85020d3d51355e8bccfbc521b52371747
Reviewed-on: https://go-review.googlesource.com/c/154459
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Keith Randall <khr@golang.org>

If someone takes a pointer to a zero-sized stack variable, it can
be incorrectly interpreted as a pointer to the next object in the
stack frame. To avoid this, add some padding after zero-sized variables.

We only need to pad if the next variable in memory (which is the
previous variable in the order in which we allocate variables to the
stack frame) has pointers. If the next variable has no pointers, it
won't hurt to have a pointer to it.

Because we allocate all pointer-containing variables before all
non-pointer-containing variables, we should only have to pad once per
frame.

Fixes #24993

Change-Id: Ife561cdfdf964fdbf69af03ae6ba97d004e6193c
Reviewed-on: https://go-review.googlesource.com/c/155698
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Method expressions where the method is implicitly declared have no
line number. The Error method of the built-in error type is one such
method.  We leave the line number at the use of the method expression
in this case.

Fixes #29389

Change-Id: I29c64bb47b1a704576abf086599eb5af7b78df53
Reviewed-on: https://go-review.googlesource.com/c/155639
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

Fixes #29383

Change-Id: I0fb2929863e153b96d32d851e25e536231e4ae65
Reviewed-on: https://go-review.googlesource.com/c/155638
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>

Fixes #27808

Change-Id: Ia643d51004c47953642a2ba41dfed281f1112be6
Reviewed-on: https://go-review.googlesource.com/c/155637Reviewed-by: Bryan C. Mills <bcmills@google.com>

When "go list" is invoked with -find, it clears the list of imports
for each package matched on the command line. This affects action IDs,
since they incorporate dependencies' action IDs. Consequently, the
build triggered by -compiled won't find sources cached by
"go build".

We can still safely cache compiled sources from multiple runs of
"go list -find -compiled" though, since cgo generated sources are not
affected by imported dependencies. This change adds a second look into
the cache in this situation.

Fixes #29371

Change-Id: Ia0ae5a403ab5d621feaa16f521e6a65ac0ae6d9a
Reviewed-on: https://go-review.googlesource.com/c/155481Reviewed-by: Bryan C. Mills <bcmills@google.com>

When building runtime/internal/atomic, the toolchain writes a symabis2
file. This file is read back in, filtered, and appended to the symabis
file. This breaks with -n, since the symabis2 file is never written.

With this change, when -n is used, an equivalent "grep" command is
printed instead. The output for -x is unchanged.

Fixes #29346

Change-Id: Id25e06e06364fc6689e71660d000f09c649c4f0c
Reviewed-on: https://go-review.googlesource.com/c/155480Reviewed-by: Bryan C. Mills <bcmills@google.com>
Run-TryBot: Bryan C. Mills <bcmills@google.com>

This change splits a testprog out of TestLockOSThreadExit and makes it
its own test. Then, this change makes the testprog exit prematurely with
a special message if unshare fails with EPERM because not all of the
builders allow the user to call the unshare syscall.

Also, do some minor cleanup on the TestLockOSThread* tests.

Fixes #29366.

Change-Id: Id8a9f6c4b16e26af92ed2916b90b0249ba226dbe
Reviewed-on: https://go-review.googlesource.com/c/155437
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Updates #26650

Change-Id: I0ec070127dcacc7fc68dd5baf125eb762e1ea846
Reviewed-on: https://go-review.googlesource.com/c/155038Reviewed-by: Bryan C. Mills <bcmills@google.com>

It was possible that

    var X interface{} = 'x'

could cause a compilation failure due to having not calculated rune's
width yet. typecheck.go normally calculates the width of things, but
it doesn't for implicit conversions to default type. We already
compute the width of all of the standard numeric types in universe.go,
but we failed to calculate it for the rune alias type. So we could
later crash if the code never otherwise explicitly mentioned 'rune'.

While here, explicitly compute widths for 'byte' and 'error' for
consistency.

Fixes #29350.

Change-Id: Ifedd4899527c983ee5258dcf75aaf635b6f812f8
Reviewed-on: https://go-review.googlesource.com/c/155380Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Robert Griesemer <gri@golang.org>

I was confused by the juxtaposition of os.Interrupt docs, which are
"guaranteed to exist on all platforms" in one sentence and then
"not implemented" in the next sentence. Reading the code reveals
"not implemented" refers specifically to the implementation of
os.Process.Signal on Windows, not to the os.Interrupt variable itself.
Reword the doc to make this distinction clearer.

Fixes #27854.

Change-Id: I5fe7cddea61fa1954cef2006dc51b8fa8ece4d6e
Reviewed-on: https://go-review.googlesource.com/c/137336Reviewed-by: Alex Brainman <alex.brainman@gmail.com>

Extended precision math/bits functions are unsigned.

Change-Id: Ic1633e9c367fc3d5a80bc503008f035db4e78945
Reviewed-on: https://go-review.googlesource.com/c/155379Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Change-Id: I84b74bc96516033bbf4a01f9aa81fe60d5a41355
Reviewed-on: https://go-review.googlesource.com/c/155317Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Fixes #28699

Change-Id: Ic340c3171bb7d91d8cb9553967c2b51e7d9daba8
Reviewed-on: https://go-review.googlesource.com/c/155177Reviewed-by: Bryan C. Mills <bcmills@google.com>

Out-of-bounds reads of globals can happen in dead code. For code
like this:

s := "a"
if len(s) == 3 {
   load s[0], s[1], and s[2]
}

The out-of-bounds loads are dead code, but aren't removed yet
when lowering. We need to not panic when compile-time evaluating
those loads. This can only happen for dead code, so the result
doesn't matter.

Fixes #29215

Change-Id: I7fb765766328b9524c6f2a1e6ab8d8edd9875097
Reviewed-on: https://go-review.googlesource.com/c/154057
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Alberto Donizetti <alb.donizetti@gmail.com>

Currently the link works also with the non-existing GOARCH armd64, but
let's correct in anyhow.

Change-Id: Ida647b8f9dd2f8460b019f5a23759f10a6da8e60
Reviewed-on: https://go-review.googlesource.com/c/155277Reviewed-by: Ian Lance Taylor <iant@golang.org>

Update to x/sys git revision 074acd46bca67915925527c07849494d115e7c43

This fixes TestFormatMessage and TestExample on windows/arm by pulling
in CL 154560 and CL 154817.

Change-Id: Ic6495fe3072b5bcc7ea68efb3f0be5fc1fe4c238
Reviewed-on: https://go-review.googlesource.com/c/155297
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Alex Brainman <alex.brainman@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

Before this CL we accepted timeouts in TestUDPZeroBytePayload to avoid
flakiness and because, according to CL 9194, the test didn't work on
some platforms. On Windows, before CL 132781, the read would always
timeout, and so since the test accepted timeouts it would pass
incorrectly. CL 132781 fixed Windows, and changed the test to not
accept timeouts in the ReadFrom case.

However, the timeout was short, and so on a loaded system the Read
might timeout not due to an error in the code, but just because the
read was not delivered. So ignoring timeouts made the test flaky, as
reported in issue #29225.

This CL tries to get to a better state by increasing the timeout to a
large value and not permitting timeouts at all. If there are systems
where the test fails, we will need to explicitly skip the test on
those systems.

Fixes #29225

Change-Id: I26863369898a69cac866b34fcb5b6ffbffab31f6
Reviewed-on: https://go-review.googlesource.com/c/154759
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Alex Brainman <alex.brainman@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

If TMP environment variable is set to Z:\, TempDir returns Z:.
But Z: refers to current directory on Z:, while Z:\ refers to root
directory on Z:. Adjust TempDir to return Z:\.

Fixes #29291

Change-Id: If04d0c7977a8ac2d9d558307502e81beb68776ef
Reviewed-on: https://go-review.googlesource.com/c/154384
Run-TryBot: Alex Brainman <alex.brainman@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Change-Id: Iaa1468296fbc98389165a152cf8b591216c22489
Reviewed-on: https://go-review.googlesource.com/c/155217Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Tracing uses cputicks() to generate trace event timestamps. cputicks()
is expected to be a high resolution clock source. On Windows/ARM,
call QueryPerformanceCounter() which is the highest resolution clock
source available.

Updates #26148

Change-Id: I987fa556060b3d60c02f07b87b9e6320b9b026e2
Reviewed-on: https://go-review.googlesource.com/c/154762Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

When a locked M has its G exit without calling UnlockOSThread, then
lockedExt on it was getting cleared. Unfortunately, this meant that
during P handoff, if a new M was started, it might get forked (on
most OSs besides Windows) from the locked M, which could have kernel
state attached to it.

To solve this, just don't clear lockedExt. At the point where the
locked M has its G exit, it will also exit in accordance with the
LockOSThread API. So, we can safely assume that it's lockedExt state
will no longer be used. For the case of the main thread where it just
gets wedged instead of exiting, it's probably better for it to keep
the locked marker since it more accurately represents its state.

Fixed #28979.

Change-Id: I7d3d71dd65bcb873e9758086d2cbcb9a06429b0f
Reviewed-on: https://go-review.googlesource.com/c/153078
Run-TryBot: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Austin Clements <austin@google.com>

This change disables the test TestArenaCollision on Darwin in race mode
to deal with the fact that Darwin 10.10 must use MAP_FIXED in race mode
to ensure we retain our heap in a particular portion of the address
space which the race detector needs. The test specifically checks to
make sure a manually mapped region's space isn't re-used, which is
definitely possible with MAP_FIXED because it replaces whatever mapping
already exists at a given address.

This change then also makes it so that MAP_FIXED is only used in race
mode and on Darwin, not all BSDs, because using MAP_FIXED breaks this
test for FreeBSD in addition to Darwin.

Updates #26475.
Fixes #29340.

Change-Id: I1c59349408ccd7eeb30c4bf2593f48316b23ab2f
Reviewed-on: https://go-review.googlesource.com/c/155097
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

This reverts change https://golang.org/cl/154758.

Restore the previous implementations of nanotime and time.now, which
are sufficiently high resolution and more efficient than
QueryPerformanceCounter. The intent of the change was to improve
resolution of tracing timestamps, but the change was overly broad
as it was only necessary to fix cputicks(). cputicks() is fixed in
a subsequent change.

Updates #26148

Change-Id: Ib9883d02fe1af2cc4940e866d8f6dc7622d47781
Reviewed-on: https://go-review.googlesource.com/c/154761Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Change-Id: I767bf77aeab62f2d42239fac9d601a8e04fe860f
Reviewed-on: https://go-review.googlesource.com/c/154957Reviewed-by: Ian Lance Taylor <iant@golang.org>

Fix two typos and don't indent the go vet example.

Change-Id: Iccec56ca5decfbae45547a00115500ed13b703e1
Reviewed-on: https://go-review.googlesource.com/c/154721Reviewed-by: Ian Lance Taylor <iant@golang.org>

This was accidentally broken by CL 127755.

Fixes #29333

Change-Id: I5e92048c64a55c1699d6c38eb4dbbd51c817b820
Reviewed-on: https://go-review.googlesource.com/c/155037
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Change-Id: I3c8ba5fdb05b6b1324648622656cc10071c70a34
Reviewed-on: https://go-review.googlesource.com/c/154997Reviewed-by: Ian Lance Taylor <iant@golang.org>

startpanic_m could be called correctly in a context where there's a
valid G, a valid M, but no P, for example in a signal handler which
panics. Currently, startpanic_m has write barriers enabled because
write barriers are permitted if a G's M is dying. However, all the
current write barrier implementations assume the current G has a P.

Therefore, in this change we disable write barriers in startpanic_m,
remove the only pointer write which clears g.writebuf, and fix up gwrite
to ignore the writebuf if the current G's M is dying, rather than
relying on it being nil in the dying case.

Fixes #26575.

Change-Id: I9b29e6b9edf00d8e99ffc71770c287142ebae086
Reviewed-on: https://go-review.googlesource.com/c/154837
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>

The previous implementation of nanotime and time.now used a time source
that was updated on the system clock tick, which has a maximum
resolution of about 1ms. On 386 and amd64, this time source maps to
the system performance counter, so has much higher resolution.
On ARM, use QueryPerformanceCounter() to get a high resolution timestamp.

Updates #26148

Change-Id: I1abc99baf927a95b472ac05020a7788626c71d08
Reviewed-on: https://go-review.googlesource.com/c/154758Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Change-Id: I4277f4130b460b42c5b51fd5a5e07f6c0e62163b
Reviewed-on: https://go-review.googlesource.com/c/154720Reviewed-by: Ian Lance Taylor <iant@golang.org>

Change-Id: I9a30c76d1299a494cce69b1060156bc2932ac8d5
Reviewed-on: https://go-review.googlesource.com/c/154857Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Dmitri Shuralyov <dmitshur@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Permission bits are most commonly viewed in string form (rwx-- etc) or
in octal form (0755), but the latter is relatively rare in Go.
Demonstrate how to print a FileMode in readable octal format.

Change-Id: I41feb801bcecb5077d4eabafdea27c149fc179a1
Reviewed-on: https://go-review.googlesource.com/c/154423
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

This change makes it so that reserving more of the address space for the
heap calls mmap with MAP_FIXED in race mode. Race mode requires certain
guarantees on where the heap is located in the address space, and on
Darwin 10.10 it appears that the kernel may end up ignoring the hint
quite often (#26475). Using MAP_FIXED is relatively OK in race mode
because nothing else should be mapped in the memory region provided by
the initial hints.

Fixes #26475.

Change-Id: Id7ac1534ee74f6de491bc04441f27dbda09f0285
Reviewed-on: https://go-review.googlesource.com/c/153897Reviewed-by: Austin Clements <austin@google.com>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

When using //line directives and unformatted code it is possible for
positions to repeat. Increment the final column position to avoid that.

Fixes #27350

Change-Id: I2faccc31360075e9814d4a024b0f98b117f8ce97
Reviewed-on: https://go-review.googlesource.com/c/153061
Run-TryBot: Rob Pike <r@golang.org>
Reviewed-by: Rob Pike <r@golang.org>

This ensures that "go test cmd/cover" tests the current cover program,
not the installed cover program.

Change-Id: I58e718ded7eb1cd8da448d0194262209bb025b20
Reviewed-on: https://go-review.googlesource.com/c/153058
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

CL 138675 added the race detector support on Linux/ARM64, but it
didn't enable the race detector tests in cmd/dist (therefore in
all.bash). Enable them.

Updates #28848

Change-Id: I4306dad2fb4167021d568436076b9f535d7f6e07
Reviewed-on: https://go-review.googlesource.com/c/149967
Run-TryBot: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

Change-Id: I598c9a2031001a6780b75c31d9015c880741b170
Reviewed-on: https://go-review.googlesource.com/c/154637Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Also update a Go 1 compatibility promise link to canonical URL.

Updates #27592
Updates #28264

Change-Id: I5994a0a63e0870c1795c65016590dfad829d26a7
Reviewed-on: https://go-review.googlesource.com/c/154618Reviewed-by: Richard Musiol <neelance@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>