Note that the spec already makes that point with a comment in the very first
example for struct field tags. This change is simply stating this explicitly
in the actual spec prose.
- gccgo and go/types already follow this rule
- the current reflect package API doesn't distinguish between absent tags
and empty tags (i.e., there is no discoverable difference)
Fixes#15412.
Change-Id: I92f9c283064137b4c8651630cee0343720717a02
Reviewed-on: https://go-review.googlesource.com/22391
Reviewed-by: Russ Cox <rsc@golang.org>
Reviewed-by: Rob Pike <r@golang.org>
A late response to CL 22163.
Change-Id: I5275a22af7081875af0256da296811f4fe9832dc
Reviewed-on: https://go-review.googlesource.com/22296
Reviewed-by: David Symonds <dsymonds@golang.org>
Per a suggestion from mdempsky.
Both gc and gccgo consider a statement list as terminating if the
last _non_empty_ statement is terminating; i.e., trailing semis are
ok. Only gotype followed the current stricter rule in the spec.
This change adjusts the spec to match gc and gccgo behavior. In
support of this change, the spec has a matching rule for fallthrough,
which in valid positions may be followed by trailing semis as well.
For details and examples, see the issue below.
Fixes#14422.
Change-Id: Ie17c282e216fc40ecb54623445c17be111e17ade
Reviewed-on: https://go-review.googlesource.com/19981
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
This will allow us to mechanically substitute these strings
using javascript (in a forthcoming change to x/tools/godoc).
Updates #14371
Change-Id: I96e876283060ffbc9f3eabaf55d6b880685453e1
Reviewed-on: https://go-review.googlesource.com/22055
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Named returned values should only be used on public funcs and methods
when it contributes to the documentation.
Named return values should not be used if they're only saving the
programmer a few lines of code inside the body of the function,
especially if that means there's stutter in the documentation or it
was only there so the programmer could use a naked return
statement. (Naked returns should not be used except in very small
functions)
This change is a manual audit & cleanup of public func signatures.
Signatures were not changed if:
* the func was private (wouldn't be in public godoc)
* the documentation referenced it
* the named return value was an interesting name. (i.e. it wasn't
simply stutter, repeating the name of the type)
There should be no changes in behavior. (At least: none intended)
Change-Id: I3472ef49619678fe786e5e0994bdf2d9de76d109
Reviewed-on: https://go-review.googlesource.com/20024
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Andrew Gerrand <adg@golang.org>
The () parentheses grouped wrongly. Removed them completely in
favor of separate 2- and 3-index slice alternatives which is
clearer.
Fixes#14477.
Change-Id: I0b7521ac912130d9ea8740b8793b3b88e2609418
Reviewed-on: https://go-review.googlesource.com/19853
Reviewed-by: Ian Lance Taylor <iant@golang.org>
The Go 1.6 release notes say that Go 1.7 will remove support
for the GO15VENDOREXPERIMENT environment variable,
making vendoring always on. Do that.
Change-Id: Iba8b79532455828869c1a8076a82edce84259468
Reviewed-on: https://go-review.googlesource.com/19615
Reviewed-by: Ian Lance Taylor <iant@golang.org>
The Go 1.6 release notes say we'll remove the “-X name value” form
(in favor of the “-X name=value” form) in Go 1.7.
Do that.
Also establish the doc/go1.7.txt file.
Change-Id: Ie4565a6bc5dbcf155181754d8d92bfbb23c75338
Reviewed-on: https://go-review.googlesource.com/19614
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Go 1.6 is soon (but not yet).
Fixes#14301.
Change-Id: I85e329b643adcb5d4fa680c5333fbc1f928d4d9d
Reviewed-on: https://go-review.googlesource.com/19550
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Chris Broadfoot <cbro@golang.org>
Fixes#13651.
Change-Id: I1d21b49e2b5bc6c507eb084d6d2553e5a9c607cf
Reviewed-on: https://go-review.googlesource.com/19552
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Chris Broadfoot <cbro@golang.org>
Go 1.6 significantly improves pause times for large heaps, but it
improves them in many other situations as well, such as when goroutine
churn is high, allocation rate is high, or when there are many
finalizers. Hence, make the statement about pause times a bit more
general.
Change-Id: Ic034b1c904c39dd1d966ee7fa96ca8bbb3614e53
Reviewed-on: https://go-review.googlesource.com/19504
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Currently we use "Section's" as the plural of the debug/elf Section
struct. Change this to "Sections" because it's not possessive and
doesn't seem to fall in to any special cases were the apostrophe is
acceptable.
Change-Id: Id5d3abbd748502a67ead3f483182ee7729db94a2
Reviewed-on: https://go-review.googlesource.com/19505
Reviewed-by: Russ Cox <rsc@golang.org>
The plan9.bell-labs.com site has fallen into disrepair.
We'll instead use the site maintained by contributor David du Colombier.
Fixes#14233
Change-Id: I0c702e5d3b091cccd42b288ea32f34d507a4733d
Reviewed-on: https://go-review.googlesource.com/19240
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: David du Colombier <0intro@gmail.com>
Also fix a few bad links.
Change-Id: If04cdd312db24a827a3c958a9974c50ab148656c
Reviewed-on: https://go-review.googlesource.com/18979
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Fixes#13954
Change-Id: I4c01e9bb3fb08e8b9fa14d4c59b7ea824ba3f0c9
Reviewed-on: https://go-review.googlesource.com/18937
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Rob Pike <r@golang.org>
Consider this code:
func f(*int)
func g() {
p := new(int)
f(p)
}
where f is an assembly function.
In general liveness analysis assumes that during the call to f, p is dead
in this frame. If f has retained p, p will be found alive in f's frame and keep
the new(int) from being garbage collected. This is all correct and works.
We use the Go func declaration for f to give the assembly function
liveness information (the arguments are assumed live for the entire call).
Now consider this code:
func h1() {
p := new(int)
syscall.Syscall(1, 2, 3, uintptr(unsafe.Pointer(p)))
}
Here syscall.Syscall is taking the place of f, but because its arguments
are uintptr, the liveness analysis and the garbage collector ignore them.
Since p is no longer live in h once the call starts, if the garbage collector
scans the stack while the system call is blocked, it will find no reference
to the new(int) and reclaim it. If the kernel is going to write to *p once
the call finishes, reclaiming the memory is a mistake.
We can't change the arguments or the liveness information for
syscall.Syscall itself, both for compatibility and because sometimes the
arguments really are integers, and the garbage collector will get quite upset
if it finds an integer where it expects a pointer. The problem is that
these arguments are fundamentally untyped.
The solution we have taken in the syscall package's wrappers in past
releases is to insert a call to a dummy function named "use", to make
it look like the argument is live during the call to syscall.Syscall:
func h2() {
p := new(int)
syscall.Syscall(1, 2, 3, uintptr(unsafe.Pointer(p)))
use(unsafe.Pointer(p))
}
Keeping p alive during the call means that if the garbage collector
scans the stack during the system call now, it will find the reference to p.
Unfortunately, this approach is not available to users outside syscall,
because 'use' is unexported, and people also have to realize they need
to use it and do so. There is much existing code using syscall.Syscall
without a 'use'-like function. That code will fail very occasionally in
mysterious ways (see #13372).
This CL fixes all that existing code by making the compiler do the right
thing automatically, without any code modifications. That is, it takes h1
above, which is incorrect code today, and makes it correct code.
Specifically, if the compiler sees a foreign func definition (one
without a body) that has uintptr arguments, it marks those arguments
as "unsafe uintptrs". If it later sees the function being called
with uintptr(unsafe.Pointer(x)) as an argument, it arranges to mark x
as having escaped, and it makes sure to hold x in a live temporary
variable until the call returns, so that the garbage collector cannot
reclaim whatever heap memory x points to.
For now I am leaving the explicit calls to use in package syscall,
but they can be removed early in a future cycle (likely Go 1.7).
The rule has no effect on escape analysis, only on liveness analysis.
Fixes#13372.
Change-Id: I2addb83f70d08db08c64d394f9d06ff0a063c500
Reviewed-on: https://go-review.googlesource.com/18584
Reviewed-by: Ian Lance Taylor <iant@golang.org>
