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Commit Graph

442 Commits

Author SHA1 Message Date
Russ Cox
5ce78b7cd2 spec: &x panics if x does
See golang.org/s/go12nil for the extended version.

R=golang-dev, r, adonovan
CC=golang-dev
https://golang.org/cl/12964043
2013-08-15 14:33:26 -04:00
Rob Pike
15e6ce2351 go_spec.html: clarify that tags are part of struct type identity
One sentence says they're ignored, another says they take part.
Fix the first.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/12741046
2013-08-15 13:15:55 +10:00
Robert Griesemer
2961d229de spec: clarify index and selector expressions
(Replacement for CL 11884043.)

1) Explain a[i] and a[i:j] where a is of type *A as
   shortcut for (*a)[i] and (*a)[i:j], respectively.

2) Together with 1), because len() of nil slices is
   well defined, there's no need to special case nil
   operands anymore.

3) The result of indexing or slicing a constant string
   is always a non-constant byte or string value.

4) The result of slicing an untyped string is a value
   of type string.

5) If the operand of a valid slice a[i:j] is nil (i, j
   must be 0 for it to be valid - this already follows
   from the in-range rules), the result is a nil slice.

Fixes #4913.
Fixes #5951.

R=r, rsc, iant, ken
CC=golang-dev
https://golang.org/cl/12198043
2013-07-31 22:25:47 -07:00
Rob Pike
bd65404eef spec: clarify a couple of issues about channels
1. They are FIFOs.
2. They are safe for concurrent access.

Fixes #5911.

R=golang-dev, dvyukov, adg
CC=golang-dev
https://golang.org/cl/11549043
2013-08-01 07:12:32 +10:00
Robert Griesemer
9f75dd7f25 undo CL 11884043 / bfd5ed8236d5
CL submitted prematurely by mistake.

««« original CL description
spec: clarify index and selector expressions

1) Explain a[i] and a[i:j] where a is of type *A as
   shortcut for (*a)[i] and (*a)[i:j], respectively.

2) Together with 1), because len() of nil slices is
   well defined, there's no need to special case nil
   operands anymore.

3) The result of indexing or slicing a constant string
   is always a non-constant byte or string value.

4) The result of slicing an untyped string is a value
   of type string.

5) If the operand of a valid slice a[i:j] is nil (i, j
   must be 0 for it to be valid - this already follows
   from the in-range rules), the result is a nil slice.

Fixes #4913.
Fixes #5951.

R=rsc, r, iant, ken
CC=golang-dev
https://golang.org/cl/11884043
»»»

R=r
CC=golang-dev
https://golang.org/cl/12170046
2013-07-31 14:10:46 -07:00
Robert Griesemer
58d2960655 spec: clarify index and selector expressions
1) Explain a[i] and a[i:j] where a is of type *A as
   shortcut for (*a)[i] and (*a)[i:j], respectively.

2) Together with 1), because len() of nil slices is
   well defined, there's no need to special case nil
   operands anymore.

3) The result of indexing or slicing a constant string
   is always a non-constant byte or string value.

4) The result of slicing an untyped string is a value
   of type string.

5) If the operand of a valid slice a[i:j] is nil (i, j
   must be 0 for it to be valid - this already follows
   from the in-range rules), the result is a nil slice.

Fixes #4913.
Fixes #5951.

R=rsc, r, iant, ken
CC=golang-dev
https://golang.org/cl/11884043
2013-07-31 13:40:01 -07:00
Robert Griesemer
f331012427 spec: update prose in Constants section
Fixes #5952.

R=r, rsc
CC=golang-dev
https://golang.org/cl/11812043
2013-07-25 09:35:55 -07:00
Robert Griesemer
63f54ae3c2 spec: move decl in example closer to use
Fixes #5862.

R=r
CC=golang-dev
https://golang.org/cl/11168043
2013-07-11 14:41:46 -07:00
Robert Griesemer
8268eadb9e spec: define notion of named type
The notion of a named type is crucial for the definition
of type identity, assignability, definitions of methods.
Explicitly introduce the notion with an extra sentence.

Fixes #5682.

R=r, rsc, iant
CC=golang-dev
https://golang.org/cl/11055043
2013-07-09 21:12:53 -07:00
Robert Griesemer
de47f68c99 spec: fix spec on conversions to match implementations
The existing compilers convert empty strings to empty
but non-nil byte and rune slices. The spec required
a nil byte and rune slice in those cases. That seems
an odd additional requirement. Adjust the spec to
match the reality.

Also, removed over-specification for conversions of
nil []byte and []rune: such nil slices already act
like empty slices and thus don't need extra language.
Added extra examples instead.

Fixes #5704.

R=rsc, r, iant
CC=golang-dev
https://golang.org/cl/10440045
2013-06-21 16:11:13 -07:00
Shenghou Ma
bdac989ef7 doc/go_spec: more examples for unspecified cases of the evaluation order
R=golang-dev, bradfitz, gri, iant, rsc
CC=golang-dev
https://golang.org/cl/7235044
2013-06-11 02:52:07 +08:00
Robert Griesemer
ab5c762a46 spec: better wording re: receiving from closed channels
As suggested by ej@evanjones.ca.

Fixes #5604.

R=r
CC=golang-dev
https://golang.org/cl/9899043
2013-05-31 11:21:37 -07:00
Robert Griesemer
6a3859f433 spec: removed old or invalid TODOs
Several old TODOs are either resolved now (e.g. when is a return
needed), or are from a time the language wasn't frozen (^ for uints
only). Consolidated the others.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/9599044
2013-05-20 14:01:07 -07:00
Robert Griesemer
bb3a32ef6e spec: fix language about "range" clause
Fixes #5434.

R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/9595044
2013-05-20 13:27:53 -07:00
Shenghou Ma
df29cdd33d doc/go_spec: fix typos
Fixes #5456.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/9400044
2013-05-15 03:50:27 +08:00
Robert Griesemer
2d846f6521 spec: fix incorrect example
Fixes #5430.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/9305043
2013-05-08 10:42:08 -07:00
Rob Pike
548c65a568 spec: add another sentence about BOMs
Although one may argue that they should be legal, gc (at least)
disallows byte order marks that are not the first code point
in the file. Added a sentence to the "Implementation restriction"
clause in the "Source code representation" section to document
this better.

Lifting this restriction (again - the rule has changed at least
twice already) would not break any existing programs, should
we later decide yet again to fiddle the rules about these little
fly specks.

R=golang-dev, dsymonds, gri
CC=golang-dev
https://golang.org/cl/8649043
2013-04-11 11:33:25 -07:00
Robert Griesemer
b34f055138 spec: Go has no 'reference types'
R=golang-dev, r
CC=golang-dev
https://golang.org/cl/8288044
2013-04-02 23:17:37 -07:00
Robert Griesemer
462a17e0f3 spec: remove most §links for the now more common in-text links
Also:
- more consistenly use "xxx" statement rather than <code>xxx</code> statement
- fix/remove unnecessary links

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/7821050
2013-03-22 15:36:04 -07:00
Rob Pike
d02089101c spec: add example showing missing return statement
Will help people find the rules by searching the spec by
having a comment saying "missing return";
"terminating statement" does not evoke the rule to the
uninitiated.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/7838044
2013-03-22 10:03:55 -07:00
Rob Pike
b636f192e2 spec: fix description of initialization
The analysis does not depend on the values of the items.
Fixes #4648.

R=golang-dev, gri, rsc
CC=golang-dev
https://golang.org/cl/7593050
2013-03-20 15:05:28 -07:00
Russ Cox
6e15683cae spec: define method values
Fixes #2280.

R=golang-dev, r, bradfitz, iant, andybalholm, gri
CC=golang-dev
https://golang.org/cl/7816045
2013-03-20 16:54:07 -04:00
Robert Griesemer
58e21ddaf9 spec: remove special int rule for shifts
The rule is not concistently followed by gc.
It appears that gccgo is ignoring it. go/types
does not implement this rule. However, both
gccgo and now go/types can compile/type-check
the entire std library (and thus all the shift
expressions occuring in it) w/o errors. For
more details see the discussion in issue 4883.

Fixes #4880.
Fixes #4881.
Fixes #4883.

R=rsc, r, iant, ken, ken, mtj, rogpeppe
CC=golang-dev
https://golang.org/cl/7707043
2013-03-15 13:55:50 -07:00
Rob Pike
c34050fd53 spec: rewrite the description of panic and recover.
The old description was misleading and inaccurate.

Fixes #4774.

R=iant, rsc, gri
CC=golang-dev
https://golang.org/cl/7761044
2013-03-12 14:28:16 -07:00
Robert Griesemer
b66df0e9ba spec: typed indices must be of integer type
The same rules apply for make arguments.

R=r, rsc, iant, ken
CC=golang-dev
https://golang.org/cl/7656043
2013-03-11 09:20:52 -07:00
Robert Griesemer
c729ed631f spec: result type of a comparison is always untyped bool
For details see the cited issue.

Fixes #4793.

R=rsc, r, iant, ken
CC=golang-dev
https://golang.org/cl/7524044
2013-03-11 09:16:29 -07:00
Robert Griesemer
51338095eb spec: clarify unsafe.Offsetof
Fixes #4905.

R=rsc, r, iant, ken
CC=golang-dev
https://golang.org/cl/7583043
2013-03-07 20:11:37 -08:00
Robert Griesemer
9905cec0dc spec: terminating statements for functions
The only functional change is the new section
on terminating statements.

There is a minor syntax rewrite (not change)
of function declarations to make it easier to
refer to the notion of a function from all places
where it is used (function decls, method decls,
and function literals).

Includes some minor fixes/additions of missing links.

Based closely on Russ' proposal.

Fixes #65.

R=rsc, r, iant, ken, bradfitz
CC=golang-dev
https://golang.org/cl/7415050
2013-03-04 13:55:35 -08:00
Robert Griesemer
4be38dde84 spec: cyclic imports are illegal
Fixes #4976.

R=r
CC=golang-dev
https://golang.org/cl/7421050
2013-03-04 12:59:40 -08:00
Robert Griesemer
67a6b4f0ef spec: fallthrough may not appear in last clause of a switch
Replacement for CL 7370053 which attempted to make fallthrough's
syntactically a part of switch statements. Because they may be
labeled, fixing that CL completely would require too much spec
surgery.

Fixes #4923.

R=r, iant, rsc, ken
CC=golang-dev
https://golang.org/cl/7416048
2013-03-01 16:45:14 -08:00
Rob Pike
7ae41e8010 doc: correct some minor HTML errors found by tidy
R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/7439046
2013-02-28 13:32:36 -08:00
Russ Cox
61e02ee901 spec: clarify when range x does not evaluate x
Fixes #4644.

R=r, adonovan
CC=golang-dev
https://golang.org/cl/7307083
2013-02-15 14:39:28 -05:00
Russ Cox
71c941b6f6 spec: only require parens around ambiguous conversions
This is documenting the status quo. The previous cleanup
added this language as an implementation restriction, but
at least for now it is really part of the language proper.

Fixes #4605.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/7305071
2013-02-11 07:48:14 -05:00
Russ Cox
7576179aa3 spec: document fp rounding during explicit constant conversion
The gc compilers already behave this way. It was an explicit
decision during the very long constant design discussions,
but it appears not to have made it into the spec.

Fixes #4398.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/7313069
2013-02-11 07:47:41 -05:00
Russ Cox
0a22018d46 spec: reject top-level init names
Fixes #4586.

R=golang-dev, remyoudompheng, r
CC=golang-dev
https://golang.org/cl/7307082
2013-02-11 07:46:39 -05:00
Russ Cox
81eb930f7e spec: clarify that any unsafe.Pointer type is okay in conversion
The spec is not clear about whether this is allowed or not,
but both compilers allow it, because the reflect implementation
takes advantage of it. Document current behavior.

Fixes #4679.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/7303064
2013-02-09 17:36:31 -05:00
Russ Cox
1b3083e68d spec: clarify that f(g()) requires that g return >= 1 value
Fixes #4573.

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/7322043
2013-02-09 14:46:55 -05:00
Oling Cat
018e89fa69 doc/go_spec: remove extra space, align tags, and change a tab to a space.
R=golang-dev, adg
CC=golang-dev
https://golang.org/cl/7198048
2013-01-24 20:46:33 +11:00
Shenghou Ma
a0b5b46ae4 doc/go_spec: cap doesn't apply to maps
Fixes #4682.

R=golang-dev, adg, dave
CC=golang-dev
https://golang.org/cl/7094062
2013-01-22 03:18:20 +08:00
Robert Griesemer
d3679726b4 spec: clarify lhs syntax for range and select
Fixes #4653.

R=rsc, r, iant, ken, thakis
CC=golang-dev
https://golang.org/cl/7135058
2013-01-18 13:59:25 -08:00
Shenghou Ma
ced57153df doc/go_spec.html: clarification about insertion during map iteration
R=mdempsky, iant, r, gri, rsc, ken
CC=golang-dev
https://golang.org/cl/7100046
2013-01-17 23:11:25 +08:00
Robert Griesemer
f1cc0f44e3 spec: clarify short variable declaration corner cases
Fixes #4612.

R=rsc, iant, ken, r
CC=golang-dev
https://golang.org/cl/7076043
2013-01-09 11:31:32 -08:00
Robert Griesemer
c863db4e87 spec: s/char_lit/rune_lit/
The spec talks explicitly about rune literals but the
respective production is still called char_lit for
historic reasons. Updated the two occurences.

Fixes #4602.

R=rsc, iant, r, ken
CC=golang-dev
https://golang.org/cl/7070048
2013-01-07 18:02:58 -08:00
Matthew Dempsky
80a87a99cc spec: Use "non-negative" instead of "positive"
Replacing division-by-power-of-2 with right-shift is valid for
zero too.

R=gri
CC=golang-dev
https://golang.org/cl/7027049
2013-01-06 16:56:06 -08:00
Robert Griesemer
614b02d22a spec: clarify language about unary operator &
A composite literal may be parenthesized when
used as operand for the unary operator &.

R=rsc, iant, r, ken
CC=golang-dev
https://golang.org/cl/6996053
2013-01-02 18:11:49 -08:00
Robert Griesemer
462860bd8d spec: more explicit comments for constant expression examples
Fixes #3814.

R=rsc, iant
CC=golang-dev
https://golang.org/cl/6920057
2012-12-12 14:25:40 -08:00
Robert Griesemer
a9a49fe962 spec: calling delete on a nil map is a no-op
This is language change. It is a backward-compatible
change but for code that relies on a run-time panic
when calling delete on a nil map (unlikely).

Fixes #4253.

R=rsc, r, iant, ken, bradfitz, rogpeppe
CC=golang-dev
https://golang.org/cl/6909060
2012-12-12 13:08:35 -08:00
Robert Griesemer
3906706297 spec: index and array/slice size constants must fit into an int
R=r, rsc, iant, ken
CC=golang-dev
https://golang.org/cl/6903048
2012-12-12 11:06:26 -08:00
Robin Eklind
1d46fc44b7 spec: Correct typo in method expressions example.
Also, remove unnecessary whitespace.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/6928045
2012-12-11 12:17:53 -05:00
Robert Griesemer
9c9e811bb3 spec: consistently use "indices" (rather than "indexes")
We have been using all three terms "indices", "indexes",
and "index expressions" indiscriminatly for index values.
With this change, "index" refers to an index value,
"indices" is the plural of "index", and "index expression"
refers to an array, slice, or map indexed by an index: a[x].

R=r, rsc, iant, ken, mtj
CC=golang-dev
https://golang.org/cl/6912056
2012-12-10 11:55:57 -08:00