Reenable dwarf output on Mac.
Was writing headers but no actual dwarf data.
Fixes#1877 (accidentally).
Workaround for issue 1878.
R=lvd
CC=golang-dev
https://golang.org/cl/4515139
The spec was adjusted in commit df410d6a4842 to allow the
implicit assignment of strutures with unexported fields in
method receivers. This change updates the compiler.
Also moved bug322 into fixedbugs and updated golden.out
to reflect the removal of the last known bug.
Fixes#1402.
R=golang-dev, gri, rsc
CC=golang-dev
https://golang.org/cl/4526069
The code for converting negative floats was
incorrectly loading an FP control word from
the stack without ever having stored it there.
Thanks to Lars Pensjö for reporting this bug.
R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/4515091
At the moment types.Check() only deals with global
types and only partially so. But the framework is
there to compute them and check for cycles. An initial
type test is passing.
First step of a series of CLs to come.
R=rsc
CC=golang-dev
https://golang.org/cl/4425063
This CL:
-- removes Response.RequestMethod string
-- adds Response.Request *Request
-- removes the finalURL result parameter from client.Get()
-- adds a gofix rule for callers of http.Get which assign
the final url to the blank identifier; warning otherwise
Caller who did:
res, finalURL, err := http.Get(...)
now need to do:
res, err := http.Get(...)
if err != nil {
...
}
finalURL := res.Request.URL.String()
R=rsc
CC=golang-dev
https://golang.org/cl/4535056
This was causing a panic in the reflect package
since type.* pointers with their low bits set are
assumed to have certain flags set that disallow
the use of reflection.
Thanks to Pavel and Taru for help tracking down
this bug.
R=rsc, paulzhol, taruti
CC=golang-dev
https://golang.org/cl/4511041
This means that the -x flag can work, which could enable
support for other languages (e.g. objective-C).
R=iant, rsc
CC=golang-dev
https://golang.org/cl/4476049
Uses of $INCLUDE and $NPROC are left over from Plan 9.
Remove them to avoid causing confusion.
R=golang-dev, r2
CC=golang-dev
https://golang.org/cl/4445079
Previously, whether declaring a type which copied the structure of a type it was referenced in via a pointer field would work depended on whether you declared it before or after the type it copied, e.g. type T2 T1; type T1 struct { F *T2 } would work, however type T1 struct { F *T2 }; type T2 T1 wouldn't.
Fixes#667.
R=rsc
CC=golang-dev
https://golang.org/cl/4313064
For example, with GOPATH set like so
GOPATH=/home/adg/gocode
And after creating some subdirectories
mkdir /home/adg/gocode/{bin,pkg,src}
I can use goinstall to install the github.com/nf/goto web server,
which depends on the github.com/nf/stat package, with
goinstall github.com/nf/goto
This downloads and installs all dependencies (that aren't already
installed) like so
/home/adg/gocode/bin/goto
/home/adg/gocode/pkg/darwin_amd64/github.com/nf/stat.a
/home/adg/gocode/src/github.com/nf/goto/...
/home/adg/gocode/src/github.com/nf/stat/...
R=rsc, niemeyer
CC=golang-dev
https://golang.org/cl/4438043
This change will allow to generate valid executable,
even if rsc disables dwarf generation, as it happend
at revision 9a64273f9d68.
R=rsc
CC=golang-dev, lvd, vcc
https://golang.org/cl/4425066
Also, 6g was passing uninitialized
Node &n2 to regalloc, causing non-deterministic
register collisions (but only when both left and
right hand side of comparison had function calls).
Fixes#1728.
R=ken2
CC=golang-dev
https://golang.org/cl/4425070
Static symbols were not being marked as such.
I also made the 'z' symbols use the first byte of
the name instead of an explicit NUL so that if
the symbol table format is ever changed, the only
place that would need updating is addhist().
R=rsc
CC=golang-dev
https://golang.org/cl/4366047
The solution may be a bit of a sledgehammer, but it looks like
a temporary situation anyway.
R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/4400042
go/types: update for export data format change
reflect: require package qualifiers to match during interface check
runtime: require package qualifiers to match during interface check
test: fixed bug324, adapt to be silent
Fixes#1550.
Issue 1536 remains open.
R=gri, ken2, r
CC=golang-dev
https://golang.org/cl/4442071
This CL gives goinstall the ability to build commands,
not just packages.
"goinstall foo.googlecode.com/hg/bar" will build the command named
"bar" and install it to GOBIN. "goinstall ." will use the name of the
local directory as the command name.
R=rsc, niemeyer
CC=golang-dev
https://golang.org/cl/4426045
I should have done this a year ago in:
changeset: 5137:686b18098944
user: Russ Cox <rsc@golang.org>
date: Thu Mar 25 14:05:54 2010 -0700
files: src/cmd/8c/swt.c
description:
make alignment rules match 8g, just like 6c matches 6g.
R=ken2
CC=golang-dev
https://golang.org/cl/760042
R=ken2
CC=golang-dev
https://golang.org/cl/4437054
Don't use the rewrite rule from a previous test
for the next test if there is no rewrite rule
provided.
R=r, r2
CC=golang-dev
https://golang.org/cl/4419045
The new reflection API makes it an error to call value.Set(x)
if x is invalid. Guard for it.
Added corresponding test case.
Fixes#1696.
R=rsc, r
CC=golang-dev
https://golang.org/cl/4398047
The list elements are already being allocated out of a
single memory buffer. We can drop the Link* pointer
following and the memory it requires, replacing it with
index operations.
The change also keeps a channel from containing a pointer
back into its own allocation block, which would create a
cycle. Blocks involved in cycles are not guaranteed to be
finalized properly, and channels depend on finalizers to
free OS-level locks on some systems. The self-reference
was keeping channels from being garbage collected.
runtime-gdb.py will need to be updated in order to dump
the content of buffered channels with the new data structure.
Fixes#1676.
R=ken2, r
CC=golang-dev
https://golang.org/cl/4411045
- replaced existing testdata/test.sh with new gofmt_test
- added initial test case for rewrite tests
TODO: Need to add more tests.
R=rsc
CC=golang-dev
https://golang.org/cl/4368063
With the (partial) resolution of identifiers done
by the go/parser, ast.Objects point may introduce
cycles in the AST. Don't follow *ast.Objects, and
replace them with nil instead (they are likely
incorrect after a rewrite anyway).
- minor manual cleanups after reflect change automatic rewrite
- includes fix by rsc related to reflect change
Fixes#1667.
R=rsc
CC=golang-dev
https://golang.org/cl/4387044
The ld time was dominated by symbol table processing, so
* increase hash table size
* emit fewer symbols in gc (just 1 per string, 1 per type)
* add read-only lookup to avoid creating spurious symbols
* add linked list to speed whole-table traversals
Breaks dwarf generator (no idea why), so disable dwarf.
Reduces time for 6l to link godoc by 25%.
R=ken2
CC=golang-dev
https://golang.org/cl/4383047
* add -diff command line option
* use scoping information in refersTo, isPkgDot, isPtrPkgDot.
* add new scoping-based helpers countUses, rewriteUses, assignsTo, isTopName.
* rename rewrite to walk, add walkBeforeAfter.
* add toy typechecker, a placeholder for go/types
R=gri
CC=golang-dev
https://golang.org/cl/4285053
If the command couldn't be found, argv[0] would be wiped.
Also, fix a print statement not to refer to make - it was a vestige of a prior form.
R=rsc, gri
CC=golang-dev
https://golang.org/cl/4360048
We replace the current Open with:
OpenFile(name, flag, perm) // same as old Open
Open(name) // same as old Open(name, O_RDONLY, 0)
Create(name) // same as old Open(name, O_RDWR|O_TRUNC|O_CREAT, 0666)
This CL includes a gofix module and full code updates: all.bash passes.
(There may be a few comments I missed.)
The interesting packages are:
gofix
os
Everything else is automatically generated except for hand tweaks to:
src/pkg/io/ioutil/ioutil.go
src/pkg/io/ioutil/tempfile.go
src/pkg/crypto/tls/generate_cert.go
src/cmd/goyacc/goyacc.go
src/cmd/goyacc/units.y
R=golang-dev, bradfitzwork, rsc, r2
CC=golang-dev
https://golang.org/cl/4357052
The error will only occur for invalid patterns, but without this
error path there is no way to know that Glob has failed due to
an invalid pattern.
R=rsc
CC=golang-dev
https://golang.org/cl/4346044
Since Go code can deadlock, this lets a testsuite driver set a
time limit for the test to run. This is simple but imperfect,
in that it only catches deadlocks in Go code, not in the
runtime scheduler.
R=r, rsc, iant2
CC=golang-dev
https://golang.org/cl/4326048
doc.go contains the details. The short story:
- command line is passed to the binary
- a new flag, -file, is needed to name files
- known flags have the "test." prefix added for convenience.
- gotest-specific flags are trimmed from the command line.
The effect should be that most existing uses are unaffected,
the ability to name files is still present, and it's nicer to use.
The downside is a lot more code in gotest.
Also allow a test to be called just Test.
R=rsc, niemeyer, rog, r2
CC=golang-dev
https://golang.org/cl/4307049
also: minor fix to parser
Note: gotest won't run the gotype test yet until
it permits TestXXX functions where XXX is empty.
R=r
CC=golang-dev
https://golang.org/cl/4300053
As a special case, multi-line raw strings (i.e., strings in `` quotes)
were not indented if they were the only token on a line. This heuristic
was meant to improve formatting for multi-line raw strings where sub-
sequent lines are not indented at the level of the surrounding code.
Multiple people have complained about this. Removing the heuristic
again because it makes the formatting more regular, easier to under-
stand, and simplifies the implementation.
- manual changes to ebnf/ebnf_test.go for readability
- gofmt -w src misc
Fixes#1643.
R=r, rsc
CC=golang-dev
https://golang.org/cl/4307045
It runs all tests correctly and saves significant time by avoiding the shell script.
However, this is just the code for the command, for review.
A separate CL will move this into the real gotest, which will take some dancing.
R=rsc, peterGo, bsiegert, albert.strasheim, rog, niemeyer, r2
CC=golang-dev
https://golang.org/cl/4281073
NewPackage creates an ast.Package node from
a set of package files and resolves unresolved
identifiers.
Also:
- Changed semantics of Scope.Insert: If an
object is inserted w/o errors, the result
is nil (before it was obj).
- Fixed an identifier resolution bug in the
parser: map keys must not be resolved.
gotype runs through several go/* packages
and successfully resolves all (non-field/method)
identifiers.
R=rog, rsc
CC=golang-dev
https://golang.org/cl/4298044
New make target "testshort" runs "gotest -test.short" and is invoked
by run.bash, which is invoked by all.bash.
Use -test.short to make one package (crypto ecdsa) run much faster.
More changes to come.
Once this is in, I will update the long-running tests to use the new flag.
R=rsc
CC=golang-dev
https://golang.org/cl/4317043
Revert changes to printer.Config. Pass in the
nodeSizes map trough an internal helper function.
R=golang-dev, rsc1
CC=golang-dev
https://golang.org/cl/4309042
Use memoization to avoid repeated recomputation of nested
node sizes. Speeds up testdata/slow.input by several orders
of magnitude.
- added respective test case
- added timeout to test code
- deleted some unrelated unused code
Fixes#1628.
R=rsc, r
CC=golang-dev
https://golang.org/cl/4274075
The -test.run and -test.bench flags were compilng the regexp for ever test
function, which was mucking up memory profiles. Add a simple wrapper
to save the compiled state so that the regexp is compiled only once for
each flag.
R=rsc
CC=golang-dev
https://golang.org/cl/4274063
Dependency on bufio crept in during last CL; this breaks the cycle.
Also add a missing '-' to the documentation.
R=rsc
CC=golang-dev
https://golang.org/cl/4274061
Swapping the goroutines lets them reuse the
communication completion on v instead of
needing a second channel (done).
R=gri
CC=golang-dev
https://golang.org/cl/4287045
This change records more metadata about what
influenced the creation of the object file.
Specifically, if a package imports, say, "fmt" but does not
need to describe any fmt types in its own export data,
that package's object file did not mention the dependency
on "fmt" before. Now it does.
Listing the import is purely informational.
It has no effect on which files are opened or consulted
when importing a package.
Import lines are marked indirect when they are needed
to explain the API but were not imported directly.
For example http imports crypto/tls and exports
a struct with a field of type tls.ConnectionState,
which contains an x509.Certificate. Since http does
not import x509 but needs to explain the x509.Certificate
type in its export data, the import of x509 is marked
as indirect. These import lines were always present;
marking them with the indirect comment makes clear
which were imported directly and which are incidental.
R=ken2
CC=golang-dev
https://golang.org/cl/4295048
Functionality was only present for
debuggging and now is available in
gocheck where is makes more sense.
R=rsc
CC=golang-dev
https://golang.org/cl/4239078
Caller code needs to change:
rw.SetHeader("Content-Type", "text/plain")
to:
rw.Header().Set("Content-Type", "text/plain")
This now permits returning multiple headers
with the same name using Add:
rw.Header().Add("Set-Cookie", "..")
rw.Header().Add("Set-Cookie", "..")
This patch also fixes serialization of headers, removing newline characters.
Fixes#488Fixes#914
R=rsc
CC=gburd, golang-dev
https://golang.org/cl/4239076
Trivial fix to '// n' comments against etype enum in go.h, as these have
got out of sync.
R=golang-dev, gri
CC=golang-dev
https://golang.org/cl/4240097
Fixes the broken linux/amd64 build.
The symbol table, itself a symbol, was having
its size rounded up to the nearest word boundary.
If the rounding add >7 zero bytes then it confused
the debug/gosym symbol table parser. So you've
got a 1/8 chance to hit the bug on an amd64 system.
Just started in the recent change because I fixed
the rounding to round to word boundary instead
of to 4-byte boundary.
R=r
CC=golang-dev
https://golang.org/cl/4241056
Much of the bulk of Go binaries is the symbol tables,
which give a name to every C string, Go string,
and reflection type symbol. These names are not worth
much other than seeing what's where in a binary.
This CL deletes all those names from the symbol table,
instead aggregating the symbols into contiguous blocks
and giving them the names "string.*", "go.string.*", and "type.*".
Before:
$ 6nm $(which godoc.old) | sort | grep ' string\.' | tail -10
59eda4 D string."aa87ca22be8b05378eb1c71...
59ee08 D string."b3312fa7e23ee7e4988e056...
59ee6c D string."func(*token.FileSet, st...
59eed0 D string."func(io.Writer, []uint8...
59ef34 D string."func(*tls.Config, *tls....
59ef98 D string."func(*bool, **template....
59effc D string."method(p *printer.print...
59f060 D string."method(S *scanner.Scann...
59f12c D string."func(*struct { begin in...
59f194 D string."method(ka *tls.ecdheRSA...
$
After:
$ 6nm $(which godoc) | sort | grep ' string\.' | tail -10
5e6a30 D string.*
$
Those names in the "Before" are truncated for the CL.
In the real binary they are the complete string, up to
a certain length, or else a unique identifier.
The same applies to the type and go.string symbols.
Removing the names cuts godoc by more than half:
-rwxr-xr-x 1 rsc rsc 9153405 2011-03-07 23:19 godoc.old
-rwxr-xr-x 1 rsc rsc 4290071 2011-03-07 23:19 godoc
For what it's worth, only 80% of what's left gets loaded
into memory; the other 20% is dwarf debugging information
only ever accessed by gdb:
-rwxr-xr-x 1 rsc rsc 3397787 2011-03-07 23:19 godoc.nodwarf
R=r, cw
CC=golang-dev
https://golang.org/cl/4245072
Change unsafe.Pointer to be its own kind of
type, instead of making it equivalent to *any.
The change complicates import and export
but avoids the need to find all the places that
operate on pointers but should not operate on
unsafe.Pointer.
Fixes#1566. (a different way)
Fixes#1582.
R=ken2
CC=golang-dev
https://golang.org/cl/4264050
As a data point, this enables goinstall to handle the standard
syscall package almost unchanged (there's one file with the _bsd
extension, and a .c file which isn't supposed to be compiled in).
R=rsc
CC=golang-dev
https://golang.org/cl/4259057
This enables goinstall to handle .go and .c files (for cgo)
which are named after the following patterns:
name_$(GOOS).*
name_$(GOARCH).*
name_$(GOOS)_$(GOARCH).*
Files with those names are only included if the $(GOOS) and
$(GOARCH) match the current system.
R=rsc
CC=golang-dev
https://golang.org/cl/4172055
The recursive algorithm used to parse types in cgo
has a bug related to building the C type representation.
As an example, when the recursion starts at a type *T,
the C type representation won't be known until type T
itself is parsed. But then, it is possible that type T
references the type **T internally. The latter
representation is built based on the one of *T, which
started the recursion, so it won't attempt to parse it
again, and will instead use the current representation
value for *T, which is still empty at this point.
This problem was fixed by introducing a simple TypeRepr
type which builds the string representation lazily,
analogous to how the Go type information is built within
the same algorithm. This way, even if a type
representation is still unknown at some level in the
recursion, representations dependant on it can still
be created correctly.
R=rsc
CC=golang-dev
https://golang.org/cl/4244052
The path package now contains only functions which
deal with slashed paths, sensible for any OS when dealing
with network paths or URLs. OS-specific functionality
has been moved into the new path/filepath package.
This also includes fixes for godoc, goinstall and other
packages which were mixing slashed and OS-specific paths.
R=rsc, gri, mattn, brainman
CC=golang-dev
https://golang.org/cl/4252044
Passing a frame size of 1 was causing the cgo callback
to push 1 byte of arguments onto the stack, making
the stack pointer misaligned, which had the effect of
hiding all the pointers on the stack from the garbage
collector.
SWIG only wraps calls to C++ virtual methods, so it
always has at least 1 argument, so SWIG does not need
to be fixed too.
Fixes#1328.
R=iant
CC=golang-dev
https://golang.org/cl/4261046
This change removes the special case which existed
for handling the initalization of the main package,
so that other modules named 'main' get properly
initialized when imported.
Note that gotest of main packages will break in most
cases without this.
R=rsc
CC=golang-dev
https://golang.org/cl/4190050
It was possible to make package run arbitrary
commands when installing if its filenames contained
make metacharacters.
R=rsc, niemeyer
CC=golang-dev
https://golang.org/cl/4248041
Fixes#1572.
Initially I tried changing things so all object
files get put in _obj, but it's too much - everything
needs changing. Perhaps some other time.
R=rsc
CC=golang-dev
https://golang.org/cl/4237050
conflict and explain that you could put the grammars
in separate packages instead.
I could be talked into rolling back the previous change
and just making a doc change instead, but I'm content
to let it stand.
R=rsc
CC=golang-dev
https://golang.org/cl/4240053
This should allow multiple goyacc grammars to be
compiled into the same binary. There's a chance it
Fixes#1562.
R=rsc, r2
CC=golang-dev
https://golang.org/cl/4256044
When providing addition file systems to godoc via -path, the
path names may be symbolic links. Follow them.
Also: better logging of error and special conditions.
R=r, dsymonds, r2
CC=golang-dev
https://golang.org/cl/4217045
The pointer will eventually let us find *T given T.
This CL just makes room for it, always storing a zero.
R=r, r2
CC=golang-dev
https://golang.org/cl/4221046
A reference to the address of weak.foo resolves at link time
to the address of the symbol foo if foo would end up in the
binary anyway, or to zero if foo would not be in the binary.
For example:
int xxx = 1;
int yyy = 2;
int weak·xxx;
int weak·yyy;
void main·main(void) {
runtime·printf("%p %p %p\n", &xxx, &weak·xxx, &weak·yyy);
}
prints the same non-nil address twice, then 0 (because yyy is not
referenced so it was dropped from the binary).
This will be used by the reflection tables.
R=iant
CC=golang-dev
https://golang.org/cl/4223044
If the filename was absolute, writeFileAtomically
used the wrong filename for ioutil.TempFile leading
to non-existent directories and the TempFile would
fail.
R=r, r2
CC=golang-dev
https://golang.org/cl/4224043
same as in issue below, never fixed on ARM
changeset: 5498:3fa1372ca694
user: Ken Thompson <ken@golang.org>
date: Thu May 20 17:31:28 2010 -0700
description:
fix issue 798
cannot allocate an audomatic temp
while real registers are allocated.
there is a chance that the automatic
will be allocated to one of the
allocated registers. the fix is to
not registerize such variables.
R=rsc
CC=golang-dev
https://golang.org/cl/1202042
R=ken2
CC=golang-dev
https://golang.org/cl/4226042
Fix problems found.
On amd64, various library routines had bigger
stack frames than expected, because large function
calls had been added.
runtime.assertI2T: nosplit stack overflow
120 assumed on entry to runtime.assertI2T
8 after runtime.assertI2T uses 112
0 on entry to runtime.newTypeAssertionError
-8 on entry to runtime.morestack01
runtime.assertE2E: nosplit stack overflow
120 assumed on entry to runtime.assertE2E
16 after runtime.assertE2E uses 104
8 on entry to runtime.panic
0 on entry to runtime.morestack16
-8 after runtime.morestack16 uses 8
runtime.assertE2T: nosplit stack overflow
120 assumed on entry to runtime.assertE2T
16 after runtime.assertE2T uses 104
8 on entry to runtime.panic
0 on entry to runtime.morestack16
-8 after runtime.morestack16 uses 8
runtime.newselect: nosplit stack overflow
120 assumed on entry to runtime.newselect
56 after runtime.newselect uses 64
48 on entry to runtime.printf
8 after runtime.printf uses 40
0 on entry to vprintf
-8 on entry to runtime.morestack16
runtime.selectdefault: nosplit stack overflow
120 assumed on entry to runtime.selectdefault
56 after runtime.selectdefault uses 64
48 on entry to runtime.printf
8 after runtime.printf uses 40
0 on entry to vprintf
-8 on entry to runtime.morestack16
runtime.selectgo: nosplit stack overflow
120 assumed on entry to runtime.selectgo
0 after runtime.selectgo uses 120
-8 on entry to runtime.gosched
On arm, 5c was tagging functions NOSPLIT that should
not have been, like the recursive function printpanics:
printpanics: nosplit stack overflow
124 assumed on entry to printpanics
112 after printpanics uses 12
108 on entry to printpanics
96 after printpanics uses 12
92 on entry to printpanics
80 after printpanics uses 12
76 on entry to printpanics
64 after printpanics uses 12
60 on entry to printpanics
48 after printpanics uses 12
44 on entry to printpanics
32 after printpanics uses 12
28 on entry to printpanics
16 after printpanics uses 12
12 on entry to printpanics
0 after printpanics uses 12
-4 on entry to printpanics
R=r, r2
CC=golang-dev
https://golang.org/cl/4188061
Flags defined in the testing package may conflict
with real flags defined in the main package, or in
any other imported package.
This change makes them less likely to be used for
other purposes.
R=r, rsc, r2
CC=golang-dev
https://golang.org/cl/4167055
Program listed http://code.google.com/p/go/issues/detail?id=1495
(with nRequester set to 10000) will crash with
runtime: failed to create new OS thread (have 4526 already; errno=8)
instead of
runtime: failed to create new OS thread (have 618 already; errno=8).
R=golang-dev, rsc, vcc
CC=golang-dev
https://golang.org/cl/4172046
In line with other functions such as Fprintf, put the
thing to be written first.
Apologies for the breakages this is sure to cause.
R=rsc, gri, adg, eds, r2, aam
CC=golang-dev
https://golang.org/cl/4169042
Neither gofmt nor godoc are making use of a Styler (for
token-specific formatting) anymore. Stylers interacted in complicated
ways with HTML-escaping which was why the printer needed an HTML mode
in the first place.
godoc now uses a more powerful and general text formatting
function that does HTML escaping, text selection, and can
handle token-specific formatting if so desired (currently
used only for comments).
As a consequence, cleaned up uses of go/printer in godoc;
simplified the various write utility functions, and also
removed the need for the "html" template format (in favor of
html-esc which now does the same and is used more pervasively).
Applied gofmt -w src misc to verify no changes occured,
and tested godoc manually.
There should be no visible changes except that (type) code
snippets presented for godoc package documentation now
uses the same formatting as for general source code and
thus comments get the comment-specific color here as well
(not the case at the moment).
(TODO: godoc needs a good automatic test suite).
R=rsc
CC=golang-dev
https://golang.org/cl/4152042
Structs defined in C as containing a field with
an enum type are currently translated to Go as
a struct with an unsigned integer field, even if
some of the values contained in the enum are
negative.
This modification takes in consideration the values
defined in the enum, and conditionally defines the
Go type as signed if necessary.
The logic introduced was tested with gcc, which
will increase the type size if it contains both
negative numbers and values greater than 2^b/2-1,
and refuses to compile values which would be
problematic (2^64-1, but in fact the ISO C
restricts the range to the size of int).
R=rsc
CC=golang-dev
https://golang.org/cl/4119058
