Austin Clements [Thu, 12 May 2016 22:10:03 +0000 (18:10 -0400)]
runtime: improve heapBitsSetType documentation
Currently the heapBitsSetType documentation says that there are no
races on the heap bitmap, but that isn't exactly true. There are no
*write-write* races, but there are read-write races. Expand the
documentation to explain this and why it's okay.
Change-Id: Ibd92b69bcd6524a40a9dd4ec82422b50831071ed
Reviewed-on: https://go-review.googlesource.com/23092 Reviewed-by: Rick Hudson <rlh@golang.org>
Austin Clements [Wed, 11 May 2016 18:57:33 +0000 (14:57 -0400)]
runtime: perform publication barrier even for noscan objects
Currently we only execute a publication barrier for scan objects (and
skip it for noscan objects). This used to be okay because GC would
never consult the object itself (so it wouldn't observe uninitialized
memory even if it found a pointer to a noscan object), and the heap
bitmap was pre-initialized to noscan.
However, now we explicitly initialize the heap bitmap for noscan
objects when we allocate them. While the GC will still never consult
the contents of a noscan object, it does need to see the initialized
heap bitmap. Hence, we need to execute a publication barrier to make
the bitmap visible before user code can expose a pointer to the newly
allocated object even for noscan objects.
Tom Bergan [Fri, 13 May 2016 05:03:46 +0000 (22:03 -0700)]
net, net/http: don't trace DNS dials
This fixes change https://go-review.googlesource.com/#/c/23069/, which
assumes all DNS requests are UDP. This is not true -- DNS requests can
be TCP in some cases. See:
https://tip.golang.org/src/net/dnsclient_unix.go#L154
https://en.wikipedia.org/wiki/Domain_Name_System#Protocol_transport
Also, the test code added by the above change doesn't actually test
anything because the test uses a faked DNS resolver that doesn't
actually make any DNS queries. I fixed that by adding another test
that uses the system DNS resolver.
David Crawshaw [Fri, 13 May 2016 16:33:27 +0000 (12:33 -0400)]
reflect: fix method type string
By picking up a spurious tFlagExtraStar, the method type was printing
as unc instead of func.
Updates #15673
Change-Id: I0c2c189b99bdd4caeb393693be7520b8e3f342bf
Reviewed-on: https://go-review.googlesource.com/23103 Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
The commit had a wrong prefix in the description line, probably
misreconginized something. As a result it broke golang.org/x/tools/godoc
and golang.org/x/tools/cmd/godoc like the following:
Brad Fitzpatrick [Thu, 12 May 2016 22:12:11 +0000 (22:12 +0000)]
net, net/http: don't trace UDP dials
The httptrace.ConnectStart and ConnectDone hooks are just about the
post-DNS connection to the host. We were accidentally also firing on
the UDP dials to DNS. Exclude those for now. We can add them back
later as separate hooks if desired. (but they'd only work for pure Go
DNS)
This wasn't noticed earlier because I was developing on a Mac at the
time, which always uses cgo for DNS. When running other tests on
Linux, I started seeing UDP dials.
Emmanuel Odeke [Wed, 11 May 2016 04:28:30 +0000 (21:28 -0700)]
cmd/build: reject non-existant directories in ImportDir
Re-apply @adg's CL https://golang.org/cl/7129048 that was
previously disabled in https://golang.org/cl/7235052 because
it broke `godoc net/http` for go1.1.
Currently `godoc net/http` seems to work fine with this CL.
Fixes #3428.
Change-Id: I7df06df02fd62dededac6ec60bea62561be59cf1
Reviewed-on: https://go-review.googlesource.com/23013
Run-TryBot: Andrew Gerrand <adg@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Andrew Gerrand <adg@golang.org>
Dmitry Vyukov [Tue, 3 May 2016 14:44:25 +0000 (16:44 +0200)]
cmd/trace: split large traces into parts
Trace viewer cannot handle traces larger than 256MB (limit on js string size):
https://github.com/catapult-project/catapult/issues/627
And even that is problematic (chrome hangs and crashes).
Split large traces into 100MB parts. Somewhat clumsy, but I don't see any other
solution (other than rewriting trace viewer). At least it works reliably now.
Fixes #15482
Change-Id: I993b5f43d22072c6f5bd041ab5888ce176f272b2
Reviewed-on: https://go-review.googlesource.com/22731 Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>
Joel Sing [Sun, 8 May 2016 16:13:03 +0000 (02:13 +1000)]
runtime: stop using sigreturn on openbsd/386
In future releases of OpenBSD, the sigreturn syscall will no longer
exist. As such, stop using sigreturn on openbsd/386 and just return
from the signal trampoline (as we already do for openbsd/amd64 and
openbsd/arm).
Change-Id: Ic4de1795bbfbfb062a685832aea0d597988c6985
Reviewed-on: https://go-review.googlesource.com/23024 Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Robert Griesemer [Wed, 11 May 2016 19:40:17 +0000 (12:40 -0700)]
cmd/compile: use ONAME instead of OPACK in binary export format
This is addressing feedback given on golang.org/cl/23052;
we do it in a separate CL to separate the functional from
the rename change.
ONAME was not used in the export data, but it's the natural node op
where we used OPACK instead. Renamed.
Furthermore, OPACK and ONONAME nodes are replaced by the type checker
with ONAME nodes, so OPACK nodes cannot occur when exporting type-checked
code. Removed a special-case for OPACK nodes since they don't appear.
Change-Id: I78b01a1badbf60e9283eaadeca2578a65d28cbd2
Reviewed-on: https://go-review.googlesource.com/23053
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Ian Lance Taylor [Wed, 11 May 2016 16:37:46 +0000 (09:37 -0700)]
cmd/cgo: remove //extern for check functions in gccgo Go prologue
The //extern comments are incorrect and cause undefined symbol
errorswhen building cgo code with -compiler=gccgo. The code is already
designed to use weak references, and that support relies on the cgo
check functions being treated as local functions.
Change-Id: Ib38a640cc4ce6eba74cfbf41ba7147ec88769ec0
Reviewed-on: https://go-review.googlesource.com/23014
Run-TryBot: Ian Lance Taylor <iant@golang.org> Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Mikio Hara [Wed, 11 May 2016 04:04:22 +0000 (13:04 +0900)]
net: fix nits found by vet
Change-Id: I323231f31c4e1e7415661ebd943a90b2f1e9da1c
Reviewed-on: https://go-review.googlesource.com/23020 Reviewed-by: Ian Lance Taylor <iant@golang.org>
Robert Griesemer [Wed, 11 May 2016 00:06:19 +0000 (17:06 -0700)]
go/importer: use correct path when checking if package was already imported
The importer uses a global (shared) package map across multiple imports
to determine if a package was imported before. That package map is usually
indexed by package (import) path ('id' in this code). However, the binary
importer was using the incoming (possibly unclean) path.
Fixes #15517.
Change-Id: I0c32a708dfccf345e0353fbda20ad882121e437c
Reviewed-on: https://go-review.googlesource.com/23012
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Alex Brainman [Thu, 7 Apr 2016 05:12:32 +0000 (15:12 +1000)]
runtime: make mksyscall_windows.go flags do what they say they do
The -systemdll and -xsys flags generate broken code in some situations
(see issue for details). Fix all that.
This CL only fixes bugs in existing code, but I have more changes comming:
golang.org/x/sys/windows is not the only package that uses mksyscall_windows.go.
golang.org/x/exp/shiny and github.com/derekparker/delve do too. I also have
few personal packages that use mksyscall_windows.go. None of those packages
are aware of new -xsys flag. I would like to change mksyscall_windows.go, so
external packages do not need to use -xsys flag. I would love to get rid of
-xsys flag altogether, but I don't see how it is possible. So I will, probably,
replace -xsys with a flag that means opposite to -xsys, and use new flag
everywhere in standard libraries. Flag name suggestions are welcome.
-systemdll flag makes users code more "secure". I would like to make -systemdll
behaviour a default for all mksyscall_windows.go users. We use that already in
standard library. If we think "secure" is important, we should encourage it in
all users code. If mksyscall_windows.go user insist on using old code, provide
-use_old_loaddll (need good name here) flag for that. So -systemdll flag will
be replaced with -use_old_loaddll.
Ian Lance Taylor [Tue, 10 May 2016 21:27:32 +0000 (14:27 -0700)]
os/user: don't create C function mygetgrouplist
Instead of exporting the C function mygetgrouplist as a global symbol to
conflict with other symbols of the same name, use trivial Go code and a
static C function.
Change-Id: I98dd667814d0a0ed8f7b1d4cfc6483d5a6965b26
Reviewed-on: https://go-review.googlesource.com/23008
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
David du Colombier [Tue, 19 Apr 2016 18:59:03 +0000 (20:59 +0200)]
os: add TestReadAtOffset
In the Plan 9 kernel, there used to be a bug in the implementation of
the pread syscall, where the channel offset was erroneously updated after
calling pread on a file.
This test verifies that ReadAt is behaving as expected.
Fixes #14534.
Change-Id: Ifc9fd40a1f94879ee7eb09b2ffc369aa2bec2926
Reviewed-on: https://go-review.googlesource.com/22244
Run-TryBot: David du Colombier <0intro@gmail.com> Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This change makes encoding and decoding support integer types in map
keys, converting to/from JSON string keys.
JSON object keys are still sorted lexically, even though the keys may be
integer strings.
For backwards-compatibility, the existing Text(Un)Marshaler support for
map keys (added in CL 20356) does not take precedence over the default
encoding for string types. There is no such concern for integer types,
so integer map key encoding is only used as a fallback if the map key
type is not a Text(Un)Marshaler.
Tilman Dilo [Mon, 9 May 2016 21:37:07 +0000 (23:37 +0200)]
crypto/cipher: execute AES-GCM decryption example
The decryption example for AES-GCM was not executed, hiding the fact
that the provided ciphertext could not be authenticated.
This commit adds the required output comment, replaces the ciphertext
with a working example, and removes an unnecessary string conversion
along the way.
Brad Fitzpatrick [Mon, 9 May 2016 17:21:11 +0000 (17:21 +0000)]
time: don't depend on the io package
The time package has never depended on the io package until
a recent change during Go 1.7 to use the io.Seek* constants.
The go/build dependency check didn't catch this because "time" was
allowed to depend on meta package group "L0", which included "io".
Adding the "io" package broke one of Dmitry's tools. The tool is
fixable, but it's also not necessary for us to depend on "io" at all
for some constants. Mirror the constants instead, and change
deps_test.go to prevent an io dependency in the future.
Change-Id: I74325228565279a74fa4a2f419643f5710e3e09f
Reviewed-on: https://go-review.googlesource.com/22960
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org>
Address two documentation issues:
1) Document that the GZIP and ZLIB footer is only verified when the
reader has been fully consumed.
2) The zlib reader is guaranteed to not read past the EOF if the
input io.Reader is also a io.ByteReader. This functionality was
documented in the flate and gzip packages but not on zlib.
David Chase [Sat, 7 May 2016 00:05:02 +0000 (17:05 -0700)]
cmd/compile: correct sparseSet probes in regalloc to avoid index error
In regalloc, a sparse map is preallocated for later use by
spill-in-loop sinking. However, variables (spills) are added
during register allocation before spill sinking, and a map
query involving any of these new variables will index out of
bounds in the map.
To fix:
1) fix the queries to use s.orig[v.ID].ID instead, to ensure
proper indexing. Note that s.orig will be nil for values
that are not eligible for spilling (like memory and flags).
2) add a test.
Fixes #15585.
Change-Id: I8f2caa93b132a0f2a9161d2178320d5550583075
Reviewed-on: https://go-review.googlesource.com/22911 Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
cmd/compile: add -linkobj flag to allow writing object file in two parts
This flag is experimental and the semantics may change
even after Go 1.7 is released. There are no changes to code
not using the flag.
The first part is for reading by future compiles.
The second part is for reading by the final link step.
Splitting the file this way allows distributed build systems
to ship the compile-input part only to compile steps and
the linker-input part only to linker steps.
The first part is basically just the export data,
and the second part is basically everything else.
The overall files still have the same broad structure,
so that existing tools will work with both halves.
It's just that various pieces are empty in the two halves.
This also copies the two bits of data the linker needed from
export data into the object header proper, so that the linker
doesn't need any export data at all. That eliminates a TODO
that was left for switching to the binary export data.
(Now the linker doesn't need to know about the switch.)
The default is still to write out a combined output file.
Nothing changes unless you pass -linkobj to the compiler.
There is no support in the go command for -linkobj,
since the go command doesn't copy objects around.
The expectation is that other build systems (like bazel, say)
might take advantage of this.
The header adjustment and the option for the split output
was intended as part of the zip archives, but the zip archives
have been cut from Go 1.7. Doing this to the current archives
both unblocks one step in the switch to binary export data
and enables alternate build systems to experiment with the
new flag using the Go 1.7 release.
Change-Id: I8b6eab25b8a22b0a266ba0ac6d31e594f3d117f3
Reviewed-on: https://go-review.googlesource.com/22500
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org> Reviewed-by: Robert Griesemer <gri@golang.org>
Dmitry Vyukov [Mon, 9 May 2016 13:11:24 +0000 (15:11 +0200)]
runtime/race: deflake test
The test sometimes fails on builders.
The test uses sleeps to establish the necessary goroutine
execution order. If sleeps undersleep/oversleep
the race is still reported, but it can be reported when the
main test goroutine returns. In such case test driver
can't match the race with the test and reports failure.
Wait for both test goroutines to ensure that the race
is reported in the test scope.
Joel Sing [Sat, 7 May 2016 15:27:45 +0000 (01:27 +1000)]
cmd/link: specify correct size for dynamic symbols in 386 elf output
Currently 386 ELF binaries are generated with dynamic symbols that have
a size of zero bytes, even though the symbol in the symbol table has
the correct size. Fix this by specifying the correct size when creating
dynamic symbols.
Issue found on OpenBSD -current, where ld.so is now producing link
warnings due to mismatched symbol sizes.
Fixes #15593.
Change-Id: Ib1a12b23ff9159c61ac980bf48a983b86f3df256
Reviewed-on: https://go-review.googlesource.com/22912 Reviewed-by: Minux Ma <minux@golang.org>
Run-TryBot: Minux Ma <minux@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Robert Griesemer [Fri, 6 May 2016 01:03:59 +0000 (18:03 -0700)]
cmd/compile: add and enable (internal) option to only track named types
The new export format keeps track of all types that are exported.
If a type is seen that was exported before, only a reference to
that type is emitted. The importer maintains a list of all the
seen types and uses that list to resolve type references.
The existing compiler infrastructure's invariants assumes that
only named types are referred to before they are fully set up.
Referring to unnamed incomplete types causes problems. One of
the issues was #15548.
Added a new internal flag 'trackAllTypes' to enable/disable
this type tracking. With this change only named types are
tracked.
Verified that this fix also addresses #15548, even w/o the
prior fix for that issue (in fact that prior fix is turned
off if trackAllTypes is disabled because it's not needed).
Elias Naur [Sat, 7 May 2016 05:24:39 +0000 (07:24 +0200)]
cmd/go: add -shared to darwin/arm{,64} default build mode
Buildmode c-archive now supports position independent code for
darwin/arm (in addition to darwin/arm64). Make PIC (-shared) the
default for both platforms in the default buildmode.
Without this change, gomobile will go install the standard library
into its separate package directory without PIC support.
Also add -shared to darwin/arm64 in buildmode c-archive, for
symmetry (darwin/arm64 always generates position independent code).
Fixes #15519
Change-Id: If27d2cbea8f40982e14df25da2703cbba572b5c6
Reviewed-on: https://go-review.googlesource.com/22920 Reviewed-by: David Crawshaw <crawshaw@golang.org>
Run-TryBot: David Crawshaw <crawshaw@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Tal Shprecher [Thu, 5 May 2016 22:14:08 +0000 (15:14 -0700)]
cmd/compile: properly handle map assignments for OAS2DOTTYPE
The boolean destination in an OAS2DOTTYPE expression craps out during
compilation when trying to assign to a map entry because, unlike slice entries,
map entries are not directly addressable in memory. The solution is to
properly order the boolean destination node so that map entries are set
via autotmp variables.
Fixes #14678
Change-Id: If344e8f232b5bdac1b53c0f0d21eeb43ab17d3de
Reviewed-on: https://go-review.googlesource.com/22833 Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Elias Naur [Wed, 9 Mar 2016 09:00:12 +0000 (10:00 +0100)]
runtime: use entire address space on 32 bit
In issue #13992, Russ mentioned that the heap bitmap footprint was
halved but that the bitmap size calculation hadn't been updated. This
presents the opportunity to either halve the bitmap size or double
the addressable virtual space. This CL doubles the addressable virtual
space. On 32 bit this can be tweaked further to allow the bitmap to
cover the entire 4GB virtual address space, removing a failure mode
if the kernel hands out memory with a too low address.
First, fix the calculation and double _MaxArena32 to cover 4GB virtual
memory space with the same bitmap size (256 MB).
Then, allow the fallback mode for the initial memory reservation
on 32 bit (or 64 bit with too little available virtual memory) to not
include space for the arena. mheap.sysAlloc will automatically reserve
additional space when the existing arena is full.
Finally, set arena_start to 0 in 32 bit mode, so that any address is
acceptable for subsequent (additional) reservations.
Before, the bitmap was always located just before arena_start, so
fix the two places relying on that assumption: Point the otherwise unused
mheap.bitmap to one byte after the end of the bitmap, and use it for
bitmap addressing instead of arena_start.
With arena_start set to 0 on 32 bit, the cgoInRange check is no longer a
sufficient check for Go pointers. Introduce and call inHeapOrStack to
check whether a pointer is to the Go heap or stack.
While we're here, remove sysReserveHigh which seems to be unused.
Brad Fitzpatrick [Fri, 6 May 2016 18:46:35 +0000 (18:46 +0000)]
net: skip more flaky net tests on flaky net builders
e.g. https://storage.googleapis.com/go-build-log/9b937dd8/linux-arm_df54a25a.log
Change-Id: Ic5864c7bd840b4f0c6341f919fcbcd5c708b14e7
Reviewed-on: https://go-review.googlesource.com/22881 Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Ian Lance Taylor [Fri, 6 May 2016 18:32:18 +0000 (11:32 -0700)]
misc/cgo/testcarchive: avoid possible pthread_create race
The old code assumed that the thread ID set by pthread_create would be
available in the newly created thread. While that is clearly true
eventually, it is not necessarily true immediately. Rather than try to
pass down the thread ID, just call pthread_self in the created thread.
Fixes #15576 (I hope).
Change-Id: Ic07086b00e4fd5676c04719a299c583320da64a1
Reviewed-on: https://go-review.googlesource.com/22880
Run-TryBot: Ian Lance Taylor <iant@golang.org> Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Brad Fitzpatrick [Fri, 6 May 2016 18:21:22 +0000 (18:21 +0000)]
net/http: wait longer for subprocess to startup in test
Might deflake the occasional linux-amd64-race failures.
Change-Id: I273b0e32bb92236168eb99887b166e079799c1f1
Reviewed-on: https://go-review.googlesource.com/22858 Reviewed-by: Ian Lance Taylor <iant@golang.org>
Brad Fitzpatrick [Fri, 6 May 2016 16:07:11 +0000 (16:07 +0000)]
os: rename remaining four os1_*.go files to os_*.go
Change-Id: Ice9c234960adc7857c8370b777a0b18e29d59281
Reviewed-on: https://go-review.googlesource.com/22853 Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Brad Fitzpatrick [Fri, 6 May 2016 16:24:57 +0000 (16:24 +0000)]
net: ignore network failures on some builders
We run the external network tests on builders, but some of our
builders have less-than-ideal DNS connectivity. This change continues
to run the tests on all builders, but marks certain builders as flaky
(network-wise), and only validates their DNS results if they got DNS
results.
Change-Id: I826dc2a6f6da55add89ae9c6db892b3b2f7b526b
Reviewed-on: https://go-review.googlesource.com/22852 Reviewed-by: Ian Lance Taylor <iant@golang.org>
Brad Fitzpatrick [Fri, 6 May 2016 16:06:02 +0000 (16:06 +0000)]
runtime: delete empty files
I meant to delete these in CL 22850, actually.
Change-Id: I0c286efd2b9f1caf0221aa88e3bcc03649c89517
Reviewed-on: https://go-review.googlesource.com/22851 Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Embed noLock struct into the following types, so `go vet -copylocks` catches
their copying additionally to types containing sync.Mutex:
- sync.Cond
- sync.WaitGroup
- sync.Pool
- atomic.Value
Richard Miller [Fri, 6 May 2016 13:21:52 +0000 (14:21 +0100)]
syscall,os,net: don't use ForkLock in plan9
This is the follow-on to CL 22610: now that it's the child instead of
the parent which lists unwanted fds to close in syscall.StartProcess,
plan9 no longer needs the ForkLock to protect the list from changing.
The readdupdevice function is also now unused and can be removed.
Change-Id: I904c8bbf5dbaa7022b0f1a1de0862cd3064ca8c7
Reviewed-on: https://go-review.googlesource.com/22842 Reviewed-by: David du Colombier <0intro@gmail.com>
Run-TryBot: David du Colombier <0intro@gmail.com> Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Robert Griesemer [Fri, 6 May 2016 00:46:58 +0000 (17:46 -0700)]
test: update test for issue 15548
Accidentally checked in the version of file c.go that doesn't
exhibit the bug - hence the test was not testing the bug fix.
Double-checked that this version exposes the bug w/o the fix.
Change-Id: Ie4dc455229d1ac802a80164b5d549c2ad4d971f5
Reviewed-on: https://go-review.googlesource.com/22837
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Minux Ma <minux@golang.org>
Brad Fitzpatrick [Fri, 6 May 2016 00:52:37 +0000 (17:52 -0700)]
cmd/go: fail with nice error message on bad GOOS/GOARCH pair
Fixes #12272
Change-Id: I2115ec62ed4061084c482eb385a583a1c1909888
Reviewed-on: https://go-review.googlesource.com/22838 Reviewed-by: Ian Lance Taylor <iant@golang.org> Reviewed-by: Minux Ma <minux@golang.org>