[SR-4155] Generic argument deduction disabled in generic context

[dabrahams]

Previous ID	SR-4155
Radar	None
Original Reporter	@dabrahams
Type	Bug
Status	Resolved
Resolution	Duplicate

Additional Detail from JIRA

Votes	0
Component/s	Compiler
Labels	Bug
Assignee	None
Priority	Medium

md5: 2f198f51481b5b4892e90af8f01334c2

duplicates:

• [SR-1789] Swift can't infer types in generic methods that reuse part of the struct/class' parameters #44398

Issue Description:

This should work, but doesn't:

(swift) struct X<T> {
          init(_: T) {}
          func f() {
            print(X(3))
        }
        }
<REPL Input>:4:13: error: 'Int' is not convertible to 'T'
    print(X(3))
           ~^~
(swift)

The problem is that inside X, all mentions of X without explicit generic parameters are assumed to be Self, rather than only using that deduction as a last resort. It's very inconvenient in my particular use-case!

[belkadan]

@DougGregor, @slavapestov, there's a bug tracking removing this "feature", right?

[slavapestov]

My preferred fix would be to write up a proposal for Swift 4 to eliminate the "self arg deduction" feature.

[dabrahams]

I actually wouldn't mind that.

[DougGregor]

Given that it's a language feature, I think we'd want a swift-evolution proposal to remove it.

[dabrahams]

@slavapestov The phrasing of this suggests you'd volunteer? ;-)

[belkadan]

Consolidating.