This change fixes problems with thread-locked goroutines using
newcoro/coroswitch/etc. Currently, the coro paths do not consider
thread-locked goroutines at all and can quickly result in broken
scheduler state or lost/leaked goroutines.
One possible fix to these issues is to fall back on goroutine+channel
semantics, but that turns out to be fairly complicated to implement and
results in significant performance cliffs. More complex thread-lock
state donation tricks also result in some fairly complicated state
tracking that doesn't seem worth it given the use-cases of iter.Pull
(and even then, there will be performance cliffs).
This change implements a much simpler, but more restrictive semantics.
In particular, thread-lock state is tied to the coro at the first call
to newcoro (i.e. iter.Pull). From then on, the invariant is that if the
coro has any thread-lock state *or* a goroutine calling into coroswitch
has any thread-lock state, that the full gamut of thread-lock state must
remain the same as it was when newcoro was called (the full gamut
meaning internal and external lock counts as well as the identity of the
thread that was locked to).
This semantics allows the common cases to be always fast, but comes with
a non-orthogonality caveat. Specifically, when iter.Pull is used in
conjunction with thread-locked goroutines, complex cases (passing next
between goroutines or passing yield between goroutines) are likely to
fail. Simple cases, where any number of iter.Pull iterators are used in
a straightforward way (nested, in series, etc.) from the same
goroutine, will work and will be guaranteed to be fast regardless of
thread-lock state.
This is a compromise for the near-term and we may consider lifting the
restrictions imposed by this CL in the future.
Fixes#65889.
Fixes#65946.
Change-Id: I3fb5791e36a61f5ded50226a229a79d28739b24e
Reviewed-on: https://go-review.googlesource.com/c/go/+/583675
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Austin Clements <austin@google.com>
This change moves the v2 tracer into the trace directory.
Updates #67367
Change-Id: I3657b4227002cb00fdf29c797434800ea796715e
Reviewed-on: https://go-review.googlesource.com/c/go/+/584538
Reviewed-by: Michael Knyszek <mknyszek@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
This CL implements the new sync/atomic AND and OR apis as well as their race
counterparts.
Fixes#61395
Change-Id: I294eefe4b3ac27bc4ed237edcbfa88a8c646d86f
GitHub-Last-Rev: f174297007
GitHub-Pull-Request: golang/go#64331
Reviewed-on: https://go-review.googlesource.com/c/go/+/544455
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Auto-Submit: Austin Clements <austin@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Keith Randall <khr@google.com>
This change removes unused parts of the v1 tracer in preperation of
the move of the v2 tracer into the trace package.
Updates #67367
Change-Id: I3e53a8afdef72dc90c2d5b514380d1077d284bc7
Reviewed-on: https://go-review.googlesource.com/c/go/+/584537
Reviewed-by: Michael Knyszek <mknyszek@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
CL 586095 wasn't needed because setting the GODEBUG value was just moved
lower in CL 563137. Now we set it twice. Remove the second set so that
it's only set once.
Change-Id: I4a830977833b007e996d0ccaec705a1da4631e6c
Reviewed-on: https://go-review.googlesource.com/c/go/+/586477
Reviewed-by: Sam Thanawalla <samthanawalla@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
This change removes the old trace code and replaces it with the new tracer.
It does the following:
- Moves the contents of the v2 directory into the parent trace directory.
- Combines the old tracer main file with the new main file.
- Replaces any existing files with the corresponding v2 files.
- Removes any unused files.
Updates #67367
Change-Id: I2237920e13588258a2442b639d562cf7f8a8e944
Reviewed-on: https://go-review.googlesource.com/c/go/+/584536
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
CL 585358 adds restrictions to disallow pull-only linknames
(currently off by default). Currently, there are quite some pull-
only linknames in user code in the wild. In order not to break
those, we add push linknames to allow them to be pulled. This CL
includes linknames found in a large code corpus (thanks Matthew
Dempsky and Michael Pratt for the analysis!), that are not
currently linknamed.
Updates #67401.
Change-Id: I32f5fc0c7a6abbd7a11359a025cfa2bf458fe767
Reviewed-on: https://go-review.googlesource.com/c/go/+/586137
Reviewed-by: Russ Cox <rsc@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Port CL 577616 from types2 to go/types allows us
to re-enable these tests.
Fixes#66859.
Fixes#67436.
Updates #50259.
Updates #65294.
Change-Id: I573e51cf16546ac1c115beac5322b51dd998c881
Reviewed-on: https://go-review.googlesource.com/c/go/+/586236
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Robert Griesemer <gri@google.com>
Reviewed-by: Alan Donovan <adonovan@google.com>
Reviewed-by: Robert Griesemer <gri@google.com>
CL 546676 inadvertently changed the error returned when reading
from the body of a canceled request. Fix it.
Rework various request cancelation tests to exercise all three ways
of canceling a request.
Fixes#67439
Change-Id: I14ecaf8bff9452eca4a05df923d57d768127a90c
Cq-Include-Trybots: luci.golang.try:gotip-linux-amd64-longtest,gotip-linux-amd64-longtest-race
Reviewed-on: https://go-review.googlesource.com/c/go/+/586315
Auto-Submit: Damien Neil <dneil@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Jonathan Amsterdam <jba@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Avoid creating duplicate usages of ANDCCconst. This is preparation for
a patch to reintroduce ANDconst to simplify the lower pass while
treating ANDCCconst like other *CC* ssa opcodes.
Also, move many of the similar rules wich retarget ANDCCconst users
to the flag result to a common rule for all compares against zero.
Change-Id: Ida86efe17ff413cb82c349d8ef69d2899361f4c0
Reviewed-on: https://go-review.googlesource.com/c/go/+/585400
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Lynn Boger <laboger@linux.vnet.ibm.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Use Process.handle field to store pidfd, and make use of it. Only use
pidfd functionality if all the needed syscalls are available.
1. Add/use pidfdWorks, which checks that all needed pidfd-related
functionality works.
2. os.StartProcess: obtain the pidfd from the kernel, if possible, using
the functionality added by CL 520266. Note we could not modify
syscall.StartProcess to return pidfd directly because it is a public
API and its callers do not expect it, so we have to use ensurePidfd
and getPidfd.
3. (*Process).Kill: use pidfdSendSignal, if available and the pidfd is
known. Otherwise, fall back to the old implementation.
4. (*Process).Wait: use pidfdWait, if available, otherwise fall back to
using waitid/wait4. This is more complicated than expected due to
struct siginfo_t idiosyncrasy.
NOTE pidfdSendSignal and pidfdWait are used without a race workaround
(blockUntilWaitable and sigMu, added by CL 23967) because with pidfd,
PID recycle issue doesn't exist (IOW, pidfd, unlike PID, is guaranteed
to refer to one particular process) and thus the race doesn't exist
either.
Rework of CL 528438 (reverted in CL 566477 because of #65857).
For #62654.
Updates #13987.
Change-Id: If5ef8920bd8619dc428b6282ffe4fb8c258ca224
Reviewed-on: https://go-review.googlesource.com/c/go/+/570036
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Kirill Kolyshkin <kolyshkin@gmail.com>
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Auto-Submit: Cherry Mui <cherryyz@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
Change-Id: I60a9abe72f786e18a59339df271c5521d2d1cda2
Reviewed-on: https://go-review.googlesource.com/c/go/+/555155
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Mauri de Souza Meneguzzo <mauri870@gmail.com>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
This patch removes redundant guards for the crash stack feature, as all
supported Go architectures now have a crash stack implementation.
Change-Id: I7ffb61c57955778d687073418130b2aaab0ff183
GitHub-Last-Rev: 6ff56d6420
GitHub-Pull-Request: golang/go#67202
Reviewed-on: https://go-review.googlesource.com/c/go/+/583416
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
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Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Run-TryBot: Mauri de Souza Meneguzzo <mauri870@gmail.com>
Add the go telemetry command to support setting and viewing the
telemetry mode. Also add the non-settable GOTELEMETRY and GOTELEMETRYDIR
variables to go env, which contain the mode and telemetry dir.
For #67111
Change-Id: Id7e89cefe30acfe3d865fa467315fe7cda975de9
Reviewed-on: https://go-review.googlesource.com/c/go/+/584535
Reviewed-by: Robert Findley <rfindley@google.com>
Reviewed-by: Sam Thanawalla <samthanawalla@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
While at it, slightly improve documentation and code.
Also, add additional test cases for #66561.
Updates #66561.
Fixes#67027.
Change-Id: I682b0e9227e065d6bbd199871c2e1ecff13edc66
Reviewed-on: https://go-review.googlesource.com/c/go/+/580937
Reviewed-by: Robert Griesemer <gri@google.com>
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Reviewed-by: Robert Findley <rfindley@google.com>
Auto-Submit: Robert Griesemer <gri@google.com>
We haven't called tlsrsakex.Value() yet at this point if we're using
FIPS, like if CipherSuites != nil. This adds needFIPS as a gate next to
CipherSuites != nil. FIPS specifies suites that would be skipped if
tlsarsakex were set.
Fixes#65991
Change-Id: I8070d8f43f27c04067490af8cc7ec5e787f2b9bd
Reviewed-on: https://go-review.googlesource.com/c/go/+/582315
Reviewed-by: Filippo Valsorda <filippo@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
TryBot-Bypass: Filippo Valsorda <filippo@golang.org>
Auto-Submit: Filippo Valsorda <filippo@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
In case of a RSA-PSS algorithm, the hashFunc of CreateCertificateRequest
is embedded in a rsa.PSSOptions struct. Given to key.Sign(), this will
generate a proper RSA-PSS signature.
Pasted from the RSA-PSS handling code in CreateCertificate().
Fixes#45990Fixes#65074
Change-Id: I8475afa79d8add107f092cc2871d38300e7b3903
GitHub-Last-Rev: 63fb0214c3
GitHub-Pull-Request: golang/go#55153
Reviewed-on: https://go-review.googlesource.com/c/go/+/431916
Auto-Submit: Filippo Valsorda <filippo@golang.org>
Reviewed-by: Filippo Valsorda <filippo@golang.org>
TryBot-Bypass: Filippo Valsorda <filippo@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Alex Scheel <alex.scheel@hashicorp.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
context.Context parameters are commonly named ctx, not cxt.
Change-Id: Icaadbcd38b054694959e5e8a058552a3e54be6d4
Reviewed-on: https://go-review.googlesource.com/c/go/+/586016
Auto-Submit: Tobias Klauser <tobias.klauser@gmail.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
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Reviewed-by: Damien Neil <dneil@google.com>
A follow-up for the recent CL 585017.
Change-Id: I9faaff7fdf62fc931fc7f64dbe238de277280730
GitHub-Last-Rev: 468d60c396
GitHub-Pull-Request: golang/go#67425
Reviewed-on: https://go-review.googlesource.com/c/go/+/586035
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Auto-Submit: Keith Randall <khr@golang.org>
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Once yield returns false, ast.Preorder must not call yield on any more
nodes. Even after the function passed to ast.Inspect returns false, it
may be invoked again with a non-nil node. Therefore, we must explicitly
truncate the inspection.
For #66339
Change-Id: I2b01e4e96a2d7aca785467c15ab59da13208c161
Reviewed-on: https://go-review.googlesource.com/c/go/+/585520
Reviewed-by: Alan Donovan <adonovan@google.com>
Reviewed-by: Robert Griesemer <gri@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
slog tries to represent a time.Time without allocations, which involves
storing its UnixNanos value. But UnixNanos is undefined for some valid
times. Provide a fallback representation for those times by storing them
in the `any` field of `Value`.
Fixes#65902.
Change-Id: I736c739a92f77d7b1122ea0831524acdd2c4703f
Reviewed-on: https://go-review.googlesource.com/c/go/+/585519
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Alan Donovan <adonovan@google.com>
HTTP requests have three separate user cancelation signals:
Transport.CancelRequest
Request.Cancel
Request.Context()
In addition, a request can be canceled due to errors.
The Transport keeps a map of all in-flight requests,
with an associated func to run if CancelRequest is
called. Confusingly, this func is *not* run if
Request.Cancel is closed or the request context expires.
The map of in-flight requests is also used to communicate
between roundTrip and readLoop. In particular, if readLoop
reads a response immediately followed by an EOF, it may
send racing signals to roundTrip: The connection has
closed, but also there is a response available.
This race is resolved by readLoop communicating through
the request map that this request has successfully
completed.
This CL refactors all of this.
In-flight requests now have a context which is canceled
when any of the above cancelation events occurs.
The map of requests to cancel funcs remains, but is
used strictly for implementing Transport.CancelRequest.
It is not used to communicate information about the
state of a request.
Change-Id: Ie157edc0ce35f719866a0a2cb0e70514fd119ff8
Reviewed-on: https://go-review.googlesource.com/c/go/+/546676
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
When scanning for an end of central directory record,
treat an EOCDR signature with a record containing a truncated
comment as an error. Previously, we would skip over the invalid
record and look for another one. Other implementations do not
do this (they either consider this a hard error, or just ignore
the truncated comment). This parser misalignment allowed
presenting entirely different archive contents to Go programs
and other zip decoders.
Fixes#66869
Change-Id: I94e5cb028534bb5704588b8af27f1e22ea49c7c6
Reviewed-on: https://go-review.googlesource.com/c/go/+/585397
Reviewed-by: Joseph Tsai <joetsai@digital-static.net>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Change-Id: Ie8ff3d1d1398618b9a229aa3cb1ef2deaa58c3d6
Reviewed-on: https://go-review.googlesource.com/c/go/+/586056
Reviewed-by: Jonathan Amsterdam <jba@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
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Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org>
It was accidently dropped in CL 563137
For #34208
Change-Id: I0aea93fda6260f07bc662dea92d1eabb26f82ca0
Reviewed-on: https://go-review.googlesource.com/c/go/+/586095
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Sam Thanawalla <samthanawalla@google.com>
Inform users that every accepted proposal should be mentioned
in the release notes to avoid generating a TODO.
Also, clarify instructions for the release team.
For #64169.
Change-Id: I03921739af31fc93f4b5808b2c7c98e28ad3da11
Reviewed-on: https://go-review.googlesource.com/c/go/+/584615
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
CL 579935 disabled usage of Alias types in the compiler, and tracks
the problem with issue #66873. The test case in #65893 passes now
with the current tip. This CL adds a test case to ensure there is no
regression once Alias types are enabled for the compiler.
Updates #66873Fixes#65893
Change-Id: I51b51bb13ca59549bc5925dd95f73da40465556d
Reviewed-on: https://go-review.googlesource.com/c/go/+/568455
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Robert Griesemer <gri@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Cuong Manh Le <cuong.manhle.vn@gmail.com>
callbackUpdateSystemStack contains a fast path to exit early without
update if SP is already within the g0.stack bounds.
This is not safe, as a subsequent call may have new stack bounds that
only partially overlap the old stack bounds. In this case it is possible
to see an SP that is in the old stack bounds, but very close to the
bottom of the bounds due to the partial overlap. In that case we're very
likely to "run out" of space on the system stack.
We only need to do this on extra Ms, as normal Ms have precise bounds
defined when we allocated the stack.
TSAN annotations are added to x_cgo_getstackbounds because bounds is a
pointer into the Go stack. The stack can be reused when an old thread
exits and a new thread starts, but TSAN can't see the synchronization
there. This isn't a new case, but we are now calling more often.
Fixes#62440.
Cq-Include-Trybots: luci.golang.try:gotip-linux-amd64-longtest
Change-Id: I5389050494987b7668d0b317fb92f85e61d798ac
Reviewed-on: https://go-review.googlesource.com/c/go/+/584597
Reviewed-by: Cherry Mui <cherryyz@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
syscall.ETXTBSY is only meaningful on Unix platforms, not on Windows.
Fixes#67356
Change-Id: I1b13292d821d61d820b396e08be9a4dd1683e843
Reviewed-on: https://go-review.googlesource.com/c/go/+/585695
Reviewed-by: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
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Reviewed-by: Michael Matloob <matloob@golang.org>
To be consistent with other tests.
Change-Id: Ibea1d3bf57a295f024e05173d17112ce46a4f0bc
Reviewed-on: https://go-review.googlesource.com/c/go/+/585895
Reviewed-by: Ian Lance Taylor <iant@google.com>
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Reviewed-by: Damien Neil <dneil@google.com>
Auto-Submit: Damien Neil <dneil@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Run telemetry.Start (without the upload) first thing so we can increment
counters in toolchain selection. Then run telemetry.StartWithUpload
after toolchain selection so we don't start the upload until after
toolchain selection has happened so we don't start something heavyweight
before selection.
Change-Id: Ia8979175a163265c3e29f6cb11a4ada4714d1d95
Reviewed-on: https://go-review.googlesource.com/c/go/+/585419
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>
Reviewed-by: Sam Thanawalla <samthanawalla@google.com>
This CL adds a new function Preorder that makes it
easier to iterate over the nodes of a syntax tree.
In particular, break, continue, and return retain
their usual continuations.
Fixes#66339
Change-Id: I438b3c23780c91ed589871ad3b8822d54e8fabc7
Reviewed-on: https://go-review.googlesource.com/c/go/+/570680
Reviewed-by: Robert Findley <rfindley@google.com>
Auto-Submit: Alan Donovan <adonovan@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Also, remove types2.Signature.SetTypeParams as it is not used
and does not exist in go/types.
Change-Id: I16c3ae988988d3735907e9c6c56e8626497ea405
Reviewed-on: https://go-review.googlesource.com/c/go/+/581817
Reviewed-by: Robert Griesemer <gri@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Robert Griesemer <gri@google.com>
Reviewed-by: Robert Findley <rfindley@google.com>
Fixes#67143.
Change-Id: I8bf9c2559f95d3d6a40874454208ae074b68875c
Reviewed-on: https://go-review.googlesource.com/c/go/+/583757
Reviewed-by: Alan Donovan <adonovan@google.com>
Reviewed-by: Robert Findley <rfindley@google.com>
Auto-Submit: Robert Griesemer <gri@google.com>
Reviewed-by: Robert Griesemer <gri@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
This is a placeholder for future options (e.g. JSON).
The parameter is temporarily variadic to avoid breaking
x/telemetry (see CL 585378), but I plan to remove
the "..." later this week.
Updates #67182
Change-Id: I3f6f39455d852f92902f8e3f007d3093cbe555db
Reviewed-on: https://go-review.googlesource.com/c/go/+/585557
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Austin Clements <austin@google.com>
The concept of an underlying type has become more complicated with the
addition of TypeParam and Alias types. Update the documentation to
clarify that it strips off Named, TypeParam, and Alias types, and to
reference the spec.
Fixes#65774
Change-Id: I40a8efe15b45591b95068acbf4ef9eae17a4cef1
Reviewed-on: https://go-review.googlesource.com/c/go/+/585456
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Alan Donovan <adonovan@google.com>
Reviewed-by: Robert Griesemer <gri@google.com>
Auto-Submit: Robert Findley <rfindley@google.com>
As mentioned in CL 584598, linkname is a mechanism that, when
abused, can break API integrity and even safety of Go programs.
CL 584598 is a first step to restrict the use of linknames, by
implementing a blocklist. This CL takes a step further, tightening
up the restriction by allowing linkname references ("pull") only
when the definition side explicitly opts into it, by having a
linkname on the definition (possibly to itself). This way, it is at
least clear on the definition side that the symbol, despite being
unexported, is accessed outside of the package. Unexported symbols
without linkname can now be actually private. This is similar to
the symbol visibility rule used by gccgo for years (which defines
unexported non-linknamed symbols as C static symbols).
As there can be pull-only linknames in the wild that may be broken
by this change, we currently only enforce this rule for symbols
defined in the standard library. Push linknames are added in the
standard library to allow things build.
Linkname references to external (non-Go) symbols are still allowed,
as their visibility is controlled by the C symbol visibility rules
and enforced by the C (static or dynamic) linker.
Assembly symbols are treated similar to linknamed symbols.
This is controlled by -checklinkname linker flag, currently not
enabled by default. A follow-up CL will enable it by default.
Change-Id: I07344f5c7a02124dbbef0fbc8fec3b666a4b2b0e
Reviewed-on: https://go-review.googlesource.com/c/go/+/585358
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Than McIntosh <thanm@google.com>
Reviewed-by: Russ Cox <rsc@golang.org>
Linknaming an instantiated generic symbol isn't particularly
useful: it doesn't guarantee the instantiation exists, and the
instantiated symbol name may be subject to change. Checked with a
large code corpus, currently there is no occurrance of linkname
to an instantiated generic symbol (or symbol with a bracket in its
name). This also suggests that it is not very useful. Linkname is
already an unsafe mechanism. We don't need to allow it to do more
unsafe things without justification.
Change-Id: Ifaa20c98166b28a9d7dc3290c013c2b5bb7682e7
Reviewed-on: https://go-review.googlesource.com/c/go/+/585458
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Than McIntosh <thanm@google.com>
