int literals should be double literals

[Hixie]

The following isn't currently possible:

double i = 0;

We commonly get complaints from our users that they receive the runtime error "type 'int' is not a subtype of type 'double'", or the analyzer warning "A value of type 'int' cannot be assigned to a variable of type 'double'", whenever they put literal numerics in their code. Literal numerics are very common in Flutter code. The problem is caused by users using integer literals where we expect doubles.

We would like to be able to accept integer literals where doubles are expected, with no runtime overhead (i.e. with the conversion done at compile time).

It seems like this should be relatively straight-forward in a strong mode environment.

[lrhn]

I can promise you that this is on our radar, and it is doable in a strongly typed setting - if you remember to type the variable.

var x = 0;
double y = x;  // whoops, x was probably inferred as int, definitely not as double.

[rmacnak-google]

s/strongly/statically/

[lrhn]

Indeed. I was trying to refer to "strong mode" colloquially, but that sentence actually means something else and it is indeed wrong.

Dart is strongly typed, and always has been. With "strong mode", it's also statically typed (except when the program is dynamic).

[natebosch]

Relevant issue on the language repo: dart-lang/language#3
And solution proposal: dart-lang/language#4

Is it worth keeping this issue in the SDK open until the feature is implemented or should we close and track on the language repo?

[jayphelps]

This is supported in Dart 2.1

[mraleph]

This is done ✅