Also updated spec on the static and dynamic types of functions literals
and static functions along with the function objects obtained from
closurizations of them.
Introduced a separate notion of what it means to be a correct override
relation (where the old text used subtyping, which won't suffice, for
several reasons).
Introduced the notion of interfaces as a separate kind of entity that
contains method signatures (again, a new kind of entity), thus
clarifying exactly which pieces of information is available during
static analysis of member accesses, e.g., instance method invocations.
Introduced 'combined' interfaces; they are needed for `mixin`
declarations, and we will specify them soon (so it should be OK to
have them now, even though they are unused).
Change-Id: I6347df49b1aa7a81d74e25904ee75c19e8ac6930
Reviewed-on: https://dart-review.googlesource.com/c/81263
Reviewed-by: Leaf Petersen <leafp@google.com>
This is already implemented by all platforms and may be in use.
Also clean up redundant requirements for constant literals and
object expressions. There is no need to check whether `x` is constant
in order to allow `const [x]` as a potentially constant expression.
We will get a compile-time error anyway if it isn't, because that is
written explicitly for constant map literals.
Similarly for map literals and constant object expressions.
Change-Id: I425489ff3c0063fa59937978267b13ee68aa039d
Reviewed-on: https://dart-review.googlesource.com/c/81274
Reviewed-by: Lasse R.H. Nielsen <lrn@google.com>
Reviewed-by: Erik Ernst <eernst@google.com>
Reviewed-by: Leaf Petersen <leafp@google.com>
Commit-Queue: Lasse R.H. Nielsen <lrn@google.com>
Changed "compile-time warning" to "static warning"; eliminated spurious
space at the beginning of each normative paragraph; added index and
changed all `{\em ..}` containing defining occurrences of words and
phrases such that they are added to the index and marked with a
diamond in the margin (to make it easy to spot definitions).
Change-Id: I688561a24d2b9955f383d6c8db2c913353d41b4b
Reviewed-on: https://dart-review.googlesource.com/c/82501
Reviewed-by: Lasse R.H. Nielsen <lrn@google.com>
The analyzer enforces the rule that when a generic type alias F has
formal type parameters X1..Xm with bounds B1..Bm, if we assume that
X1..Xm are types satisfying the corresponding bounds then it must be
the case that every type which occurs in the body of F must be
regular-bounded.
In other words, the bounds on the left hand side of `=` must imply
the bounds applicable to every type on the right hand side.
---------- NEW TEXT ----------
I just discovered that it is _not_ possible to skip the check on
every super-bounded parameterized type based on a generic type
alias: It is certainly possible to have a type which is correctly
super-bounded according to the type parameter bounds on the left
hand side of `=` in the type alias declaration, and still have a
right hand side where some types are not well-bounded. Consider the
following declarations:
class B<Y1 extends Y2, Y2, Y3 extends num> {}
typedef F<X extends num> = B<num, Object, X> Function();
According to the declarations to the left of `=`, `F<Object>`
is a correct super-bounded type, because it is not
regular-bounded (`Object <\: num`), and `F<Null>` is regular-bounded
(`Null <: num`).
Also, when the declared bound of `X` is satisfied, we are
guaranteed that each type on the right hand side is regular-bounded
(if parameterized, it receives type arguments that satisfy all
the specified bounds).
But consider the result of applying `F` to `Object`:
B<num, Object, Object> Function();
That's not a type where all subterms which are types are
well-bounded:
B<num, Object, Object> is not regular-bounded because
`Object <\: num` (third type argument).
B<num, Object, Object> is not super-bounded because
B<num, Null, Null> is not regular-bounded because
`num <\: Null` (violating `Y1 extends Y2`).
So there is no way we can prove that this check can be skipped,
because we have a pretty simple counter-example!
I'm currently adjusting the text to re-introduce the check.
---------- OLD TEXT, NOT VALID ----------
This must be specified, because it justifies the _removal_ of a
requirement that we had in the feature specification
super-bounded-types.md: It was required for every application of a
generic type alias F to a list of actual type arguments <T1..Tk>
such that the resulting parameterized type F<T1..Tk> was
super-bounded that both the parameterized type F<T1..Tk> and every
type in the resulting type [T1/X1..Tk/Xk]U (where U is the body of
F and X1..Xk are its formal type parameters) be well-bounded.
But when the bounds of F imply satisfaction of the bounds of all
types that occur in the body of F, it's trivially true that all
types in the resulting type are regular-bounded for the result
of substituting Null for covariant top types and Object for
contravariant Null for every super-bounded F<T1..Tk>. I'm looking
into a proof sketch for the result that this implies that any
well-bounded generic type alias application yields a type that
contains only well-bounded types.
This would be a very welcome simplification (because it was an
inconvenient complication that we had to check both the left hand
side and the right hand side of a type alias whenever we
encountered a super-bounded type expressed via a type alias), and
I believe that it will also make the tools run faster (because they
can now skip all those checks of every type that occurs in the body
for every super-bounded usage of a type alias.
Change-Id: Icd70649ebaed41b193aeb0cb6f08d06aed0ee5bd
Reviewed-on: https://dart-review.googlesource.com/c/79743
Reviewed-by: Leaf Petersen <leafp@google.com>
Reviewed-by: Lasse R.H. Nielsen <lrn@google.com>
Also mention it in the `external const factory Symbol` constructor.
This only relevant for constant expressions that may be used as
switch case expressions or constant map keys.
See #32557.
Bug: http://dartbug.com/32557
Change-Id: Ie82799f3f0d39c21c10765338a7dfeb74a582add
Reviewed-on: https://dart-review.googlesource.com/c/81242
Commit-Queue: Lasse R.H. Nielsen <lrn@google.com>
Reviewed-by: Leaf Petersen <leafp@google.com>
Reviewed-by: Erik Ernst <eernst@google.com>
Partially resolves issue #34349.
Also note that #34365 and #34319 are affected by this change.
Change-Id: I1d9023464090ff2c07f9dc062353202ddb82ba25
Reviewed-on: https://dart-review.googlesource.com/c/78121
Reviewed-by: Leaf Petersen <leafp@google.com>
This makes some parts of the specification explicit,
and rephrases it so that it is easier to recognize the separate cases.
Change-Id: Ifdbb5c11ec3b3fe80737642f230ee291a18a5841
Reviewed-on: https://dart-review.googlesource.com/c/80824
Commit-Queue: Lasse R.H. Nielsen <lrn@google.com>
Reviewed-by: Erik Ernst <eernst@google.com>
Cf. SDK issue 34722, where the need for this clarification arose.
Change-Id: I3b1692931506410e77c59004b1ed1981a17a6f3d
Reviewed-on: https://dart-review.googlesource.com/c/78982
Reviewed-by: Leaf Petersen <leafp@google.com>
Also fix some typos.
Change-Id: Id8ed6d22c9e7c900c4062b2cbc5b68abf93d11ba
Reviewed-on: https://dart-review.googlesource.com/c/77080
Commit-Queue: Lasse R.H. Nielsen <lrn@google.com>
Reviewed-by: Jenny Messerly <jmesserly@google.com>
Reviewed-by: Erik Ernst <eernst@google.com>
The existing version covers generic classes only, but we should
use exactly the same rules for parameterized type aliases, which was
actually already specified in all the nested cases (e.g., `A` would mean
`A<F<dynamic>>` with the declarations `typedef F<X> = X Function();` and
`class A<X extends F<X>> {}`, but there were no rules for a plain `F`).
A rendered version corresponding to patchset 3 is available here:
https://gist.github.com/eernstg/6deffcde2cbe79f8ba499b3aac950900
Change-Id: Ic265ccc736c65361919e860b1ab7ecb947c2c066
Reviewed-on: https://dart-review.googlesource.com/c/76660
Reviewed-by: Lasse R.H. Nielsen <lrn@google.com>
.. and always use a plain `constant` in normative text. Also fixed a few
LaTeX issues.
Change-Id: I5682f5c5b22120691c620144318f0670c4ba0a24
Reviewed-on: https://dart-review.googlesource.com/76980
Reviewed-by: Lasse R.H. Nielsen <lrn@google.com>
The existing specification was underspecifying potentially constant expressions,
effectively relying on evaluation to determine whether an expression was
potentially constant.
This change specifies potentially constant recursively using only the syntax
of the expressions.
Adds short-circuting to `?:`, `??`, `||` and `&&` expressions,
so for `String x`, the expression `x != null && x.length > 0`
is compile-time constant.
The original specification requred evaluation of the latter half
even when `x` is null. We can now avoid this because we can require that the
unused expression is a potentially constant expression without having to
check if it, or any part of it, is a compile-time constant expression.
Allows `x == null` and `x != null` as compile-time constant expression
independently of the type of `x`.
Allows `e as T` as a compile-time constant expression. Types are more
important in Dart 2, so you need a way to adjust typing in some cases,
even in compile-time constant expressions.
Change-Id: I02bf0b77013c3b3ced8cd46334db378787cc2d57
Reviewed-on: https://dart-review.googlesource.com/36220
Commit-Queue: Lasse R.H. Nielsen <lrn@google.com>
Reviewed-by: Erik Ernst <eernst@google.com>
Reviewed-by: Leaf Petersen <leafp@google.com>
We should avoid the situation where `class C extends A with M {}`
requires generation of noSuchMethod forwarders _in the superclass
`A with M`_ when neither `A` nor `M` has an implementation of
`foo`, but `A with M` has a non-trivial noSuchMethod.
If we _do_ generate those nSM forwarders, that will just obscure that
any attempt to invoke `super.foo()` in `C` should be an error.
Note that this is about generating forwarders _in the mixin application
which is the superclass_, it is not about copy-down of forwards from
the class `M` that was used to obtain the mixin in the first place.
Also note that it would be inconvenient to require all methods to be
implemented in `A with M` as used in `abstract C extends A with M {}`,
and it would also be rather funny if we were to say that `A with M` is
abstract when `C` is abstract, and concrete when `C` is concrete.
So I think the only reasonable choice is to make those superclasses
which are mixin applications abstract.
Note that dart:mirrors ought to reflect this, in a separate issue,
if it is not already the case.
Change-Id: If221b2c73b17bd55017d4d5ee4fdb8daf203e195
Reviewed-on: https://dart-review.googlesource.com/76640
Reviewed-by: Lasse R.H. Nielsen <lrn@google.com>
Also update type dynamic and other sections especially affected.
Change-Id: I432992b8190f13b2aea73d524fc9b17d3ef24b41
Reviewed-on: https://dart-review.googlesource.com/75340
Reviewed-by: Lasse R.H. Nielsen <lrn@google.com>
Also corrected some "includes" to "has" when talking about members of
an interface.
Change-Id: Ib8917c2a9f40fce82ab1e41e0e766c87065b168a
Reviewed-on: https://dart-review.googlesource.com/75880
Reviewed-by: Lasse R.H. Nielsen <lrn@google.com>
Also fixed many syntax related glitches.
Change-Id: I926b93a54ad28d05389a44c969fc2288933f8584
Reviewed-on: https://dart-review.googlesource.com/75580
Reviewed-by: Lasse R.H. Nielsen <lrn@google.com>
---------------- NEW description (old description shown at end):
This CL is now a reorganization, problem fixing, clarifying update
to dartLangSpec.tex which was created as part of the work on the
rules for call method extraction. That is, all the call method
extraction specific elements have been _deleted_ from this CL
(they will reappear as a separate CL later). This CL is now only
performing "general clean-up work" which is needed in order to
perform many kinds of updates (including call method extraction,
but also anything else where the dynamic semantics depends on the
static analysis & desugaring).
------------------------------------------------ OLD description
Introduced rules for call method extraction.
The previous update to dartLangSpec.tex dealt with invocations, but
omitted the transformation whereby `e` becomes `e.call` when `e` has
a type which is a class with a `call` method and the context expects
a value of type `Function` or of a function type. This CL adds some
rules dealing with that and introduces a concept for the transformation
itself.
One part is missing for the initial patch set: There are no rules
specifying that call method extraction should be applied to actual
arguments. The problem is that static checking of actual arguments
to various invocations (function expression invocation, ordinary
method invocation, super invocation, etc.etc.) seems to be "delegated"
partially to section `Binding Actuals to Formals`, but that section
never defines the syntax for the function which is being invoked and
it is in general rather dynamic in nature. So I'm not quite sure
that the references to static checking at the end of that section
are located optimally.
Some adjustments may therefor be needed before we can specify this
particular feature for actual arguments.
Change-Id: Ia2ab6f16cd50e10a3c467722035f0dc4adb50587
Reviewed-on: https://dart-review.googlesource.com/51323
Reviewed-by: Lasse R.H. Nielsen <lrn@google.com>
The previous phrasing ("A constant expression is ... a literal string
where any interpolated expression is a compile-time constant ...") was
ambiguous: did it mean "... where at least one interpolated expression
is a compile-time constant ..." or did it mean "... where every
interpolated expression (if there are any) is a compile-time constant
..."?
Clearly the intended meaning is that all interpolated expressions are
required to be compile-time constants, otherwise we would allow
nonsense like this:
void f(int i) {
const x = 0;
const s = "$x $i"; // Ok because x is const (!)
}
Changing the word to "every" avoids the ambiguity.
Change-Id: I3a1dd38a8bc0dc9cddc7b504ea8e7de5afdf8990
Reviewed-on: https://dart-review.googlesource.com/74321
Reviewed-by: Leaf Petersen <leafp@google.com>
Commit-Queue: Paul Berry <paulberry@google.com>
This updates the Dart language spec to allow
```
class C with M
```
where currently the above declaration would require `extends Object`.
Change-Id: Ibb5834b264be7b2c5adb79dfa9a24ad5e1fa539a
Reviewed-on: https://dart-review.googlesource.com/73684
Reviewed-by: Lasse R.H. Nielsen <lrn@google.com>
Reviewed-by: Leaf Petersen <leafp@google.com>
Commit-Queue: Dan Rubel <danrubel@google.com>
The valid return tests were misnamed and hence not run. Also remove
duplicate tests from one file, and add status to the informal proposal.
Change-Id: I20179e81a0281302056f601ee3b7a51e2aec180e
Reviewed-on: https://dart-review.googlesource.com/73562
Commit-Queue: Leaf Petersen <leafp@google.com>
Reviewed-by: Kevin Millikin <kmillikin@google.com>
\; caused the following compilation error
! Missing $ inserted.
<inserted text>
$
l.7845 }
I have removed the backslash, and placed the semicolon between a pair
of $ to make it render like the one in the grammer-environment.
Change-Id: If57e61f61b460d159b6f14d70c9c9f343114cf70
Reviewed-on: https://dart-review.googlesource.com/71760
Commit-Queue: Daniel Hillerström <hillerstrom@google.com>
Reviewed-by: Erik Ernst <eernst@google.com>
The current specification only prohibits expressions statements where the
expression *is* a map, not those that *start with* a map.
Implementations have always rejected those starting with a map.
Bug: http://dartbug.com/725
Change-Id: I805a6f82d1afdcf335aff73e74dac1f14e5a6afe
Reviewed-on: https://dart-review.googlesource.com/71247
Commit-Queue: Lasse R.H. Nielsen <lrn@google.com>
Reviewed-by: Erik Ernst <eernst@google.com>
In changing the proposed spec to address comments in a way that was intended to be
non-breaking, I accidentally introduced some new (unintended) restrictions. This
fixes the spec, rolls back the change in analyzer, and adjusts the language tests
appropriately.
Change-Id: I487b0eaacbfa1447d4ee909c0a56e435c2088990
Reviewed-on: https://dart-review.googlesource.com/70462
Reviewed-by: Mike Fairhurst <mfairhurst@google.com>
Also remove 64-bit constraint on integer literals when compiling to JavaScript.
Effectively, all integer literals are treated the same way when compiling to JavaScript numbers.
Change-Id: Ib625457d65c40600291edbf391c82f37ad27701a
Reviewed-on: https://dart-review.googlesource.com/70144
Commit-Queue: Lasse R.H. Nielsen <lrn@google.com>
Reviewed-by: Erik Ernst <eernst@google.com>
We need to clarify the following case:
`dynamic foo() => print('');`,
`dynamic bar() { return print(''); }`
that is, using `return e` where `e` has type `void`, when the return
type of the enclosing function is `dynamic` (inferred or explicit).
We do not currently have any elements in the generalized-void.md
whitelist for that, so it's an error. However, invalid_returns.md
from https://dart-review.googlesource.com/c/sdk/+/60401 implies
(patchset 6: line 19-20 and 34-35) that it is allowed.
It is my impression that we agree on invalid_returns.md, and also
that it describes the current behavior (maybe not 100%?).
This indicates to me that we should, probably, add an element to
the above-mentioned whitelist to allow it.
This CL makes that change to generalized-void.md.
Change-Id: I0326081960deda907b3b4ff34bd2d60f7c9dc35b
Reviewed-on: https://dart-review.googlesource.com/64341
Reviewed-by: Erik Ernst <eernst@google.com>
The issue was raised recently that there must be generated forwarders
for some method signatures that we had not previously mentioned in
nosuchmethod-forwarders.md: Private methods with an inaccessible name,
that is, private methods declared in a different library than the
current target of nSM forwarder generation.
Given that such forwarders are semantically significant (a tear-off
performed in the library where the abstract private method declaration
is located would tear off a generated forwarder, rather than causing
an invocation of `noSuchMethod`), we need to specify this.
This CL adds such a specification to nosuchmethod-forwarders.md.
This CL addresses SDK issue #33725, and SDK issue #33727 is related
being concerned with the implementation in the common front
end.
Change-Id: Iedbcdd8b4c8df95c6038022f72b3211ec1b76649
Reviewed-on: https://dart-review.googlesource.com/64380
Reviewed-by: Erik Ernst <eernst@google.com>
