Static checker warns on optional arguments with default values assigned, when using explicit interface.

[DartBot]

This issue was originally filed by [email protected]

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What steps will reproduce the problem?
interface Foo{
  myFunction(int argA, [int argB]);
}

class Bar implements Foo{
  //static warning here:
  //"cannot override default method 'myFunction', default value doesn't match 'null'"
  myFunction(int argA, [int argB = 0]){ ... }
}

What is the expected output? What do you see instead?
I think this should not warn. Setting default value of optional args in the interface is not allowed.

[DartBot]

This comment was originally written by [email protected]

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Sorry, forgot to mention: Build 8394.

[dgrove]

Added Area-Analyzer, Triaged labels.

[bwilkerson]

Actually, methods defined in an interface are allowed to specify a default value.

According to the spec:

It is a static warning if an instance method m1 overrides an instance member m2, the signature of m2 explicitly specifies a default value for a formal parameter p and the signature of m1 specifies a different default value for p.

and:

It is a static warning if an interface method m1 overrides an interface method m2, the signature of m2 explicitly specifies a default value for a formal parameter p and the signature of m1 specifies a different default value for p.

The problem is that we are creating a warning when a default value was not explicitly provided.

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Added this to the M1 milestone.

[scheglov]

Set owner to @scheglov.
Added Accepted label.

[scheglov]

https://chromiumcodereview.appspot.com/10534084

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Added Started label.

[scheglov]

https://code.google.com/p/dart/source/detail?r=8496

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Added Fixed label.