Issue 12210013: Implement subtype for type variables.

Issue 12210013: Implement subtype for type variables. (Closed)

Created:
7 years, 10 months ago by Johnni Winther

Modified:
7 years, 8 months ago

Reviewers:
karlklose

CC:
reviews_dartlang.org, ahe

Base URL:
https://dart.googlecode.com/svn/branches/bleeding_edge/dart

Visibility:
Public.

More Reviews

Patch Set 1 #

Total comments: 3

Created: 7 years, 10 months ago

Download [raw] [tar.bz2]

	Unified diffs	Side-by-side diffs	Stats (+107 lines, -10 lines)			Patch
M	sdk/lib/_internal/compiler/implementation/dart_types.dart	View	2 chunks	+5 lines, -2 lines	3 comments	Download
M	sdk/lib/_internal/compiler/implementation/elements/elements.dart	View	1 chunk	+2 lines, -2 lines	0 comments	Download
M	sdk/lib/_internal/compiler/implementation/elements/modelx.dart	View	1 chunk	+2 lines, -2 lines	0 comments	Download
M	sdk/lib/_internal/compiler/implementation/mirrors/dart2js_mirror.dart	View	1 chunk	+1 line, -1 line	0 comments	Download
M	sdk/lib/_internal/compiler/implementation/resolution/members.dart	View	1 chunk	+3 lines, -3 lines	0 comments	Download
M	tests/compiler/dart2js/subtype_test.dart	View	2 chunks	+94 lines, -0 lines	0 comments	Download

Messages

Total messages: 5 (0 generated)

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ahe

DBC https://codereview.chromium.org/12210013/diff/1/sdk/lib/_internal/compiler/implementation/dart_types.dart File sdk/lib/_internal/compiler/implementation/dart_types.dart (right): https://codereview.chromium.org/12210013/diff/1/sdk/lib/_internal/compiler/implementation/dart_types.dart#newcode795 sdk/lib/_internal/compiler/implementation/dart_types.dart:795: return isSubtype(typeVariable.upperBound, s); How do you deal with: ...

7 years, 10 months ago (2013-02-05 15:14:40 UTC) #2

Johnni Winther

https://codereview.chromium.org/12210013/diff/1/sdk/lib/_internal/compiler/implementation/dart_types.dart File sdk/lib/_internal/compiler/implementation/dart_types.dart (right): https://codereview.chromium.org/12210013/diff/1/sdk/lib/_internal/compiler/implementation/dart_types.dart#newcode795 sdk/lib/_internal/compiler/implementation/dart_types.dart:795: return isSubtype(typeVariable.upperBound, s); On 2013/02/05 15:14:40, ahe wrote: > ...

7 years, 10 months ago (2013-02-05 18:45:57 UTC) #3

ahe

7 years, 10 months ago (2013-02-18 08:22:18 UTC) #5

DBC

https://codereview.chromium.org/12210013/diff/1/sdk/lib/_internal/compiler/im...
File sdk/lib/_internal/compiler/implementation/dart_types.dart (right):

https://codereview.chromium.org/12210013/diff/1/sdk/lib/_internal/compiler/im...
sdk/lib/_internal/compiler/implementation/dart_types.dart:795: return
isSubtype(typeVariable.upperBound, s);
On 2013/02/05 18:45:57, Johnni Winther wrote:
> On 2013/02/05 15:14:40, ahe wrote:
> > How do you deal with:
> > 
> > class Foo<T extends S, S extends T> {
> >   haveFun(T t, S s) {
> >     t = s;
> >     s = t;
> >   }
> > }
> 
> I don't. I think this should be part of the (still unimplemented) check on
> bounds.

I don't like having known unbounded recursion in a type checker. I think this
would be really simple to implement using a variant of asInstanceOf. This method
can keep looking for an upper bound as long as it isn't a type variable or
itself.

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