Expected 0-2 type arguments, but got 1

[ghost]

TypeScript Version: 3.2.0-dev.20181020

Code

new Map<string>();

(as of #28052)

Expected behavior:

No overload expects 1 type argument, but overloads do exist that expect either 0 or 2 type arguments.

Actual behavior:

Expected 0-2 type arguments, but got 1.

Related Issues: #19220

[fatcerberus]

To be clear, the issue is with the error message and not the error itself, correct?

[ghost]

Right.

[pesca]

@andy-ms As per #19220, the error should give the next lowest and highest arity. What if the arity is not between a pair? Consider:

new Map<any, any, any>();

We get Expected 0-2 type arguments, but got 3 which isn't contradictory (like the one this issue is trying to address) but still misleading.

Also the expected behavior is incorrect when the given arity does not equal 1. Example: No overload expects 3 type argument. Several error messages overlook this detail. Possible solutions:

• Relevant morphemes are parenthesized: No overload expects 5 type argument(s)
• Relevant words are parametrized

[ghost]

Relevant words are parametrized

I don't think that would work with localization -- we can't have No_overload_expects_5_type_0, "arguments" because "arguments" isn't the right word in yiddish. So we have to create two separate error codes if we want to support plurals.

As for Expected 0-2 type arguments, but got 3, I suppose that could be No overload expects 3 arguments, but an overload does exist that expects 2 arguments.

[pesca]

@andy-ms OK, I opened a PR.

[DanielRosenwasser]

Thanks @pesca!