Emit compile-time error for incorrectly used optional parameters.

Emit compile-time error for incorrectly used optional parameters.

BUG=dartbug.com/13183
R=ahe@google.com

Committed: https://code.google.com/p/dart/source/detail?r=27513

[ahe, 2013-09-13 07:17:04]

lgtm

I like this approach very much: the parser handles the issue while it is simple,
but the program can still be analyzed so more problems can be detected!

I'm adding Luke and Kathy in case they have suggestions for the error messages.

https://codereview.chromium.org/23456030/diff/1/sdk/lib/_internal/compiler/im...
File sdk/lib/_internal/compiler/implementation/warnings.dart (right):

https://codereview.chromium.org/23456030/diff/1/sdk/lib/_internal/compiler/im...
sdk/lib/_internal/compiler/implementation/warnings.dart:423: howToFix: "Remove
the default value or make the parameter optional.",
"Remove ..." sound like a command/order, could you make it sound more like a
suggestion?

https://codereview.chromium.org/23456030/diff/1/sdk/lib/_internal/compiler/im...
sdk/lib/_internal/compiler/implementation/warnings.dart:435: "Error: Named
parameters must use ':'.",
I have a suspicion that Luke would say this error message is a bit rude ;-)

How about: "A named parameter can't be followed by '=', a default value of a
named parameter is indicated with ':'."

As far as I understand Luke's advice, this follows the guide line: what is wrong
and why?

https://codereview.chromium.org/23456030/diff/1/sdk/lib/_internal/compiler/im...
sdk/lib/_internal/compiler/implementation/warnings.dart:436: howToFix: "Change
'=' to ':'",
Suggestion?

https://codereview.chromium.org/23456030/diff/1/sdk/lib/_internal/compiler/im...
sdk/lib/_internal/compiler/implementation/warnings.dart:444: "Error: Positional
optional parameters must use '='.",
Possibly rude, see above.

https://codereview.chromium.org/23456030/diff/1/sdk/lib/_internal/compiler/im...
sdk/lib/_internal/compiler/implementation/warnings.dart:445: howToFix: "Change
':' to '='",
Suggestion?

[Kathy Walrath, 2013-09-13 17:59:08]

A few comments on the wording. Thanks for including me!

https://codereview.chromium.org/23456030/diff/6001/sdk/lib/_internal/compiler...
File sdk/lib/_internal/compiler/implementation/warnings.dart (right):

https://codereview.chromium.org/23456030/diff/6001/sdk/lib/_internal/compiler...
sdk/lib/_internal/compiler/implementation/warnings.dart:384: howToFix: "Try to
change or remove the type argument.",
Try to change or remove
->
Try changing or removing

("Try to blank" is fine, grammatically, but it's inconsistent with the "Try
blanking" wording elsewhere in these messages.)

https://codereview.chromium.org/23456030/diff/6001/sdk/lib/_internal/compiler...
sdk/lib/_internal/compiler/implementation/warnings.dart:433: "Error:
Non-optional parameters can't have default a value.",
default a value -> a default value

https://codereview.chromium.org/23456030/diff/6001/sdk/lib/_internal/compiler...
sdk/lib/_internal/compiler/implementation/warnings.dart:435: "Try removing the
default value or make the parameter optional.",
This should be:

Try removing the default value or making the parameter optional.

https://codereview.chromium.org/23456030/diff/6001/sdk/lib/_internal/compiler...
sdk/lib/_internal/compiler/implementation/warnings.dart:447: "Error: Named
parameters use ':' to specify a default value.",
Shouldn't this mention/describe the error/problem? Maybe:

Error: Named parameters can't use '=' to specify a default value.

https://codereview.chromium.org/23456030/diff/6001/sdk/lib/_internal/compiler...
sdk/lib/_internal/compiler/implementation/warnings.dart:456: "Error: Positional
optional parameters use '=' to specify a default "
Again, this doesn't describe the error. Maybe: 

Error: Positional optional parameters can't use ':' to specify a default value.

[karlklose, 2013-09-16 07:58:59]

Thanks Kathy and Peter!

https://codereview.chromium.org/23456030/diff/6001/sdk/lib/_internal/compiler...
File sdk/lib/_internal/compiler/implementation/warnings.dart (right):

https://codereview.chromium.org/23456030/diff/6001/sdk/lib/_internal/compiler...
sdk/lib/_internal/compiler/implementation/warnings.dart:433: "Error:
Non-optional parameters can't have default a value.",
On 2013/09/13 17:59:08, Kathy Walrath wrote:
> default a value -> a default value

Done.

https://codereview.chromium.org/23456030/diff/6001/sdk/lib/_internal/compiler...
sdk/lib/_internal/compiler/implementation/warnings.dart:435: "Try removing the
default value or make the parameter optional.",
On 2013/09/13 17:59:08, Kathy Walrath wrote:
> This should be:
> 
> Try removing the default value or making the parameter optional.

Done.

https://codereview.chromium.org/23456030/diff/6001/sdk/lib/_internal/compiler...
sdk/lib/_internal/compiler/implementation/warnings.dart:447: "Error: Named
parameters use ':' to specify a default value.",
On 2013/09/13 17:59:08, Kathy Walrath wrote:
> Shouldn't this mention/describe the error/problem? Maybe:
> 
> Error: Named parameters can't use '=' to specify a default value.

Done.

https://codereview.chromium.org/23456030/diff/6001/sdk/lib/_internal/compiler...
sdk/lib/_internal/compiler/implementation/warnings.dart:456: "Error: Positional
optional parameters use '=' to specify a default "
On 2013/09/13 17:59:08, Kathy Walrath wrote:
> Again, this doesn't describe the error. Maybe: 
> 
> Error: Positional optional parameters can't use ':' to specify a default
value.

Done.

[karlklose, 2013-09-16 08:14:45]

Committed patchset #3 manually as r27513 (presubmit successful).