The metadata for the workspace packages may not be available when we
need it, so we should allow loading a single package ID. This can be
improved in follow-up CLs by consolidating the individual IDs into one
call to packages.Load. Some adjustments from CL 212102 were split out
into this CL.
Change-Id: I173a79a3cb136530bc99d093f1c2be189eac8ce2
Reviewed-on: https://go-review.googlesource.com/c/tools/+/212628
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Heschi Kreinick <heschi@google.com>
In one of my previous refactoring changes, I lost the fact that the
context should be detached before invalidating a file's contents. If
this function is canceled, we will be in a bad state.
Also, small change to return ctx.Err() instead of a custom error message
from (*packageHandle).check.
Change-Id: I19e513e09e438feee105fdd89cb7364a0c3c5e7f
Reviewed-on: https://go-review.googlesource.com/c/tools/+/212104
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
Reviewed-by: Heschi Kreinick <heschi@google.com>
Now that `go list` errors are sufficient for us to determine a circular
dependency, we don't need to cache errors on dependency packages.
Change-Id: I0633aeb356f93d21afed3371d61d7eae7de255ac
Reviewed-on: https://go-review.googlesource.com/c/tools/+/212197
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
Run-TryBot: Rohan Challa <rohan@golang.org>
Reviewed-by: Rohan Challa <rohan@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This change eliminates the extra step of calling GetFile on the view and
getting the FileHandle from the snapshot. It also eliminiates the
redundant source.File type. Follow up changes will clean up the file
kind handling, since it still exists on the fileBase type.
Change-Id: I635ab8632821b36e062be5151eaab425a5698f60
Reviewed-on: https://go-review.googlesource.com/c/tools/+/211778
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Heschi Kreinick <heschi@google.com>
After the addition of golang/go#35964, the import cycle error now
has the import stack attached in the message. This CL parses that
stack and attached the import cycle diagnostic to the import versus
just adding it to the first character of the .go file.
Fixesgolang/go#33085
Change-Id: I6f5f067c338879b898829951236f816aa63d9dfa
Reviewed-on: https://go-review.googlesource.com/c/tools/+/210942
Run-TryBot: Rohan Challa <rohan@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>
This change will provide a more useful error when you
are self importing a package. It has TODOs in place to propagate the
"import cycle not allowed" error from go list to the user.
Updates golang/go#33085
Change-Id: Ia868a7c688b0f0a7a9689cfda5ea8cea8ae1faff
Reviewed-on: https://go-review.googlesource.com/c/tools/+/209857
Run-TryBot: Rohan Challa <rohan@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>
When searching for implementations we look at all packages in the
workspace. We do a full parse since we need to look for non-exported
types and look in functions for type declarations. However, we always
type check a package's dependencies in export-only mode to save work.
This leads to what I call the "two world" syndrome where you have both
the export-only and full-parse versions of a package in play at once.
This is problematic because mirror objects in each version do not
compare equal.
For example:
-- a/a.go --
package a
type Breed int
const Mutt Breed = 0
type Dog interface{ Breed() Breed }
-- b/b.go --
package b
import "a"
type dog struct{}
func (dog) Breed() a.Breed { return a.Mutt }
---
In this situation, the problem is "b" loads its dependency "a" in
export only mode so it gets one version of the "a.Breed" type. The
user opens package "a" directly so it gets fully type checked and has
a second version of "a.Breed". The user searches for "a.Dog"
implementations, but "b.dog" does not implement the fully-loaded
"a.Dog" because it returns the export-only version of the "a.Breed"
type.
Fix it by always loading in-workspace dependencies in full parse mode.
We need to load them in full parse mode anyway if the user does find
references or find implementations.
In writing a test I fixed an incorrect import in the testdata. This
uncovered an unrelated bug which made a different implementation test
very flaky. I disabled it for now since I couldn't see a fix simple
enough to slip into this commit.
Fixesgolang/go#35857.
Change-Id: I01509f57d54d593e62c895c7ecb93eb5f780bec7
Reviewed-on: https://go-review.googlesource.com/c/tools/+/209759
Run-TryBot: Muir Manders <muir@mnd.rs>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>
We were previously returning errors when we failed to load/check a
user's workspace folder, but now we suppress all errors. We shouldn't
disable gopls functionality if something is broken in a user's workspace
folder, rather, we should fall back to the file= queries that will run
when a user edits a file.
Change-Id: Iae05174ca80d2573c0222ac42f29e5556bda0134
Reviewed-on: https://go-review.googlesource.com/c/tools/+/209420
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Cottrell <iancottrell@google.com>
When packages.Load'ing cgo packages, the authored files show up in
GoFiles, and the generated files show up in CompiledGoFiles. We need the
AST and type information for the latter, since they're the only thing we
can type check. But we also need the contents (and column mapper) for
the authored file so that we can navigate into it.
Store GoFiles in package metadata and checked Packages. Parse the extra
files, just for their mappers. Refactor the View functions a little bit,
since there's only one place that actually needs to find the mapper for
a file.
Updates golang/go#35720.
Change-Id: I9f96872a9a592bf0e11da27ebd8976c6db8752c9
Reviewed-on: https://go-review.googlesource.com/c/tools/+/208502
Run-TryBot: Heschi Kreinick <heschi@google.com>
Reviewed-by: Ian Cottrell <iancottrell@google.com>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>
As we improve support for cgo we'll need to reference GoFiles, not just
CompiledGoFiles. "Files" is right out.
I think I got everything that needs renaming but please let me know if
not.
Updates golang/go#35720.
Change-Id: I97a6ebf5b395535de0d5f4f8b3f84b46ca34643f
Reviewed-on: https://go-review.googlesource.com/c/tools/+/208101
Run-TryBot: Heschi Kreinick <heschi@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>
If a user is typing fast, they will quickly invalidate many snapshots.
We don't want to stack up a bunch of stale type check and analysis
operations, so we should propagate cancellation through the cache.
Handles are long-lived, so we may cancel an operation only to
restart it again later. Also, there may be multiple operations waiting on
the same computation, and just because one is cancelled doesn't mean we
should necessarily stop. The easiest way to support all that was to add
an explicit state to each handle, and track the number of waiters.
See the code for more details on Handle life cycles.
As far as I can tell, the rest of gopls is prepared for this behavior.
I added an explicit check to the type checking code, where I was worried
it might get overly confused. But long-term it would probably be good to
return an error from Get.
Change-Id: I3ea6e141b52b94300a41248d3f2e039b023709d0
Reviewed-on: https://go-review.googlesource.com/c/tools/+/206879
Run-TryBot: Heschi Kreinick <heschi@google.com>
Reviewed-by: Ian Cottrell <iancottrell@google.com>
We don't want to return an error for the whole package when we are just
building out error positions.
Change-Id: I56b5b88ff2b4b44da8a372ade81cd9b1534235c4
Reviewed-on: https://go-review.googlesource.com/c/tools/+/206597
Reviewed-by: Heschi Kreinick <heschi@google.com>
Run-TryBot: Heschi Kreinick <heschi@google.com>
Closing over the checkPackageHandle creates a cycle that forces the
checkPackageHandle not to be garbage collected until the value is
created. If a value is never created, the handle will not be collected.
Change-Id: I0f94557da917330ebe307a0e843b16ca7382e210
Reviewed-on: https://go-review.googlesource.com/c/tools/+/204079
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
Reviewed-by: Ian Cottrell <iancottrell@google.com>
This change encompasses the refactorings needed to correctly implement
CL 204079. The goal of this CL is to make the actual relevant diffs more
clear.
Change-Id: I38acfd436e2380be790910e01b6e37d8280e9100
Reviewed-on: https://go-review.googlesource.com/c/tools/+/204139
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
Reviewed-by: Ian Cottrell <iancottrell@google.com>
This change eliminates the need for the importer struct. We should no
longer need the "seen" map for cycle detection. This is because
go/packages will not return import maps with cycles, and we fail in the
Import function if we see an import we do not recognize.
Change-Id: I06922c74e07eb47ce63b56fa2ac2099e7fc8bd8a
Reviewed-on: https://go-review.googlesource.com/c/tools/+/202299
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Cottrell <iancottrell@google.com>
Now that we are using the memoize package to cache analysis results, we
can use that cache for suggested fixes.
Change-Id: I42905a6fe575f49d38979d53d58ea8ec59210ae0
Reviewed-on: https://go-review.googlesource.com/c/tools/+/203278
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Heschi Kreinick <heschi@google.com>
We don't need to worry about a package's errors unless it is the
top-level package. Also fix some fallback logic in the type error range
computation.
Change-Id: Ib26b5e25bd70193ea24ec4a197811eedf69b0e2c
Reviewed-on: https://go-review.googlesource.com/c/tools/+/202622
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Michael Matloob <matloob@golang.org>
This change effectively reverts CL 202039. This CL was a mistake, as it
creates a cycle. Snapshots hold CheckPackageHandles, which in turn hold
pkgs.
Change-Id: I944304cb365f0ef98b5e54ea38edea6cece40453
Reviewed-on: https://go-review.googlesource.com/c/tools/+/202740
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
Reviewed-by: Heschi Kreinick <heschi@google.com>
This change modifies the invalidContent function to take a file change
type. This allows us to eliminate the separate invalidateMetadata
function. The logic of watching changed files is then further pushed
into the caching layer.
Updates golang/go#34218
Change-Id: Id31b3931c45ec408b6e7b4a362e00f9091ba4f70
Reviewed-on: https://go-review.googlesource.com/c/tools/+/201221
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Cottrell <iancottrell@google.com>
A continuation of CL 202298, only for analysis errors.
Change-Id: I957d52cef31938ef66be73463e92695a5b56869c
Reviewed-on: https://go-review.googlesource.com/c/tools/+/202540
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Cottrell <iancottrell@google.com>
This change adds a source.Error type which is used to collect the error
information that comes out of the loading, parsing, and type checking
stages. We also add specific sources per-error, rather than having them
all be labeled as "LSP".
This change will enable follow-ups that do a better job of extracting
error ranges.
Change-Id: I3fbb5e42d66aa2c5bb1b2f41d1eadfc45f3a749b
Reviewed-on: https://go-review.googlesource.com/c/tools/+/202298
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Cottrell <iancottrell@google.com>
We were caching the package before setting the handle, so a
checkPackageHandle might be in use before it was fully created.
Change-Id: Ic98e7c351cbed5e4caa87098e95ad04d4f54f8df
Reviewed-on: https://go-review.googlesource.com/c/tools/+/202040
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
Reviewed-by: Heschi Kreinick <heschi@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
A package really should always be associated with its snapshot rather
than its view. This eliminates some extra parameters in a few utility
functions.
Change-Id: I60f9b7286e0072d3268602f6bd32052a3d2e5559
Reviewed-on: https://go-review.googlesource.com/c/tools/+/202039
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
Reviewed-by: Heschi Kreinick <heschi@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
There was a regression where gopls would not type-check any package with
a bad import. This change fixes the regression and adds a test to make
sure it doesn't happen again.
Change-Id: I3acf0917d46e9444c20135559f057f0ecd20e15b
Reviewed-on: https://go-review.googlesource.com/c/tools/+/201539
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Michael Matloob <matloob@golang.org>
Reviewed-by: Ian Cottrell <iancottrell@google.com>
This span resulted in misleading information, since it would appear any
time you called the Check function. This function often returns cached
results, so it's not particularly useful.
Change-Id: I26be652a99b906fb2e8703ff9af86fbe2ef5fc5d
Reviewed-on: https://go-review.googlesource.com/c/tools/+/201219
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
Reviewed-by: Michael Matloob <matloob@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This change makes sure that actionHandles are cached within the
snapshot, to minimize the cost of re-computing action handles on each
run of go/analysis.
Change-Id: If6191c5224285eb207aebb997787ea551a47fbaa
Reviewed-on: https://go-review.googlesource.com/c/tools/+/201098
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Michael Matloob <matloob@golang.org>
This change moves to the approach of caching the analysis using the
memoize package. This means that we will do less work, as we no longer
need to recompute results that are unchanged. The cache key for an
analysis is simply the key of the CheckPackageHandle, along with the
name of the analyzer.
Change-Id: I0e589ccf088ff1de5670401b7207ffa77a254ceb
Reviewed-on: https://go-review.googlesource.com/c/tools/+/200817
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
Reviewed-by: Ian Cottrell <iancottrell@google.com>
This change includes dependencies in the cache keys for
CheckPackageHandles. This should fix the issue with propagating results
to reverse dependencies.
Updates golang/go#34410
Change-Id: I025b7f0d6b0dcaa89c3461ebd94eadd35de4955f
Reviewed-on: https://go-review.googlesource.com/c/tools/+/198317
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Cottrell <iancottrell@google.com>
This change does not complete the work to handle snapshots correctly,
but it does implement the behavior of re-building the snapshot on each
file invalidation.
It also moves to the approach of caching the FileHandles on the snapshot,
rather than in the goFile object, which is now not necessary.
Finally, this change shifts the logic of metadata invalidation into the
content invalidation step, so there is less logic to decide if we should
re-load a package or not.
Change-Id: I18387c385fb070da4db1302bf97035ce6328b5c3
Reviewed-on: https://go-review.googlesource.com/c/tools/+/197799
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Cottrell <iancottrell@google.com>
This change uses the missing imports detection to return diagnostics and
warning messages to the user.
Updates golang/go#34484
Change-Id: If7bb7e702b8bdbd7e1ad5e26f93acc50d16209b0
Reviewed-on: https://go-review.googlesource.com/c/tools/+/196985
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Cottrell <iancottrell@google.com>
Currently, we cache source.CheckPackageHandles for each file and package
that we are aware of, as well as dependencies. This is not necessary,
since the active packages pin their imports in memory.
Change-Id: Ia0101f4d4a2d36d5baeb890af3d7c8baec297847
Reviewed-on: https://go-review.googlesource.com/c/tools/+/196982
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Cottrell <iancottrell@google.com>
This change shifts our approach to make sure that a top-level package
only ever imports "trimmed" packages.
Change-Id: I63c35791ef6efad7dac248a9ff877835f46df9ed
Reviewed-on: https://go-review.googlesource.com/c/tools/+/196523
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Cottrell <iancottrell@google.com>
This change encodes an invariant that, a dependency package will only
ever be parsed with trimmed ASTs.
Updates golang/go#34410
Change-Id: I2ceab3672c0bae0b98cec2a8e60b92a0c01a900f
Reviewed-on: https://go-review.googlesource.com/c/tools/+/196537
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Cottrell <iancottrell@google.com>
Parse errors need to be treated separately from actual errors when
parsing a file. Parse errors are treated more like values, whereas
actual errors should not be propagated to the user. This enables us to
delete some of the special handling for context.Canceled errors.
Change-Id: I93a02f22b3f54beccbd6bcf26f04bb8da0202c25
Reviewed-on: https://go-review.googlesource.com/c/tools/+/195997
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Cottrell <iancottrell@google.com>
We had too many options for functions to use to get type information for
a package. Now we stick with having one option to get the check package
handles, and then the caller can refine the results as needed.
Change-Id: I81f69a670e1539854ee23b6f364159a7de9b782f
Reviewed-on: https://go-review.googlesource.com/c/tools/+/194457
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Cottrell <iancottrell@google.com>
A mapper is always uniquely tied to a file at a specific version, so
just build it when we get a new *ast.File. We build the mapper using the
*token.File associated with the particular *ast.File, which is why there
is one per ParseGoHandle instead of FileHandle.
Change-Id: Ida40981ef91f6133cdd07e9793337fcd67510fba
Reviewed-on: https://go-review.googlesource.com/c/tools/+/194517
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
Reviewed-by: Ian Cottrell <iancottrell@google.com>
Our original caching plan was to use only the file ParseGoHandles as
cache keys to define a given package. However, because of package test
variants, we cannot rely on files alone. A package may have the exact
same set of files, but be a test variant. Add the ID to the key to avoid
clobbering entries in the cache.
Also, remove the unused metadata ID cache.
Change-Id: I4b33de1f83f6c769d23441e98a2a7324ff0fa1b0
Reviewed-on: https://go-review.googlesource.com/c/tools/+/194571
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Cottrell <iancottrell@google.com>
There are issues with contexts being propagated through the calls to
type-checking, and I think that a lot of these were related to us using
the importer's context. Instead, we should propagate the context from
the store as much as possible - only using the importer's context when
absolutely necessary (in the call to Import). This change propagates the
correct context where possible.
Updates golang/go#34103
Change-Id: I4bdc37d014ee1f775b720c9e7ad8abffffcf6ba3
Reviewed-on: https://go-review.googlesource.com/c/tools/+/193480
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Cottrell <iancottrell@google.com>
The memoize store passes a detached context to the value getter
function. This is important since if the value getter experiences a
context cancellation it will end up caching context.Canceled, which
you never want. When type checking, we were ignoring the detached
context and using the "real" request context. This would cause the
context.Canceled error to get cached and continue popping up in
various situations.
Fix by swapping the importer's context to the detached context. It is
a little messy since the importer stores the context as a field. I
added a defer to restore the original context since it doesn't seem
correct to let the detached context escape the memoize function.
Updates golang/go#33678
Change-Id: I20dd466b0072ac2e856adbe993364f77e93ab054
Reviewed-on: https://go-review.googlesource.com/c/tools/+/192719
Reviewed-by: Rebecca Stambler <rstambler@golang.org>
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
This change will just make it a bit easier to debug the context
cancellation errors.
Change-Id: I580751ac04e3357031678eb31914828029c96e4b
Reviewed-on: https://go-review.googlesource.com/c/tools/+/190412
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Cottrell <iancottrell@google.com>
This is a straight move of some code with no changes.
It splits the part of the telemetry code that will become a standalone library from the bit that belongs in the lsp.
Change-Id: Icedb6bf1f3711da9251450531729984df6df7787
Reviewed-on: https://go-review.googlesource.com/c/tools/+/190403
Run-TryBot: Ian Cottrell <iancottrell@google.com>
Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This change eliminates the need for the package cache map, and instead
stores package type information in the store. We still have to maintain
invalidation logic because the key is not computed correctly.
Change-Id: I1c2a7502b99491ef0ff68d68c9f439503d531ff1
Reviewed-on: https://go-review.googlesource.com/c/tools/+/185438
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Cottrell <iancottrell@google.com>
This change fixes documentation for completion items by using cached
package and AST information to derive the documentation. We also add
testing for documentation in completion items.
Change-Id: I911fb80f5cef88640fc06a9fe474e5da403657e3
Reviewed-on: https://go-review.googlesource.com/c/tools/+/189237
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
Reviewed-by: Ian Cottrell <iancottrell@google.com>
The `files` slice is used twice. First it's used to get all results from `ph.Parse`, and then it's reused to filter all `nil` values (which may have been returned by the `ph.Parse` method).
After the loop to "filter" out all the `nil` values, we also need to strip the remaining values.
I also changed the ordering so that we first check the errors and
only then perform this loop. That way the code will return earlier
when the context was canceled.
Partially fixes#33531 by prevention the panic reported in that issue.
Change-Id: I09478e765adcd0384ec4745921eb5c5aea405ef2
Reviewed-on: https://go-review.googlesource.com/c/tools/+/189397
Reviewed-by: Rebecca Stambler <rstambler@golang.org>
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This relates to https://github.com/golang/go/issues/31374 and should switch all instances within `gopls` to use `x/errors` instead of `fmt` to create new errors.
Change-Id: I18339b75d12418d852e0dcc2ba0ed6c2970783b3
GitHub-Last-Rev: f4a55d9b79e7458ef1f1e06cb5eabbabd884f321
GitHub-Pull-Request: golang/tools#108
Reviewed-on: https://go-review.googlesource.com/c/tools/+/179880
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>
