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2b301938e0
In the specific case of sr-69, and in a bunch of other code where errors arise involving generic function application, better type constraint failure diagnoses are being masked by the overly conservative implementation in evaluateCloseness(). If the actual arg types didn’t exactly match the parameter types, we’d always diagnose a non-specific arguments-don’t-match error instead of allowing discovery of better errors from the constraint system. This commit adds more cases where evaluateCloseness will return CC_ExactMatch, specifically in application of functions with one or more arguments of a single archetype, like `func min<T: Comparable>(T, T) -> T`. It verifies that the actual argument type isSubstitutableFor() the archetype, and that all such arguments are of the same type. Anything more complicated than that still has the previous behavior of not matching at all. I think the final answer here ought to be to make a constraint system with type variables for any archetypes, add appropriate constraints to the actual args and then see if the system can solve all the argument constraints at once. That’s because the next most complicated set of things to handle in the stdlib are things like `func -<T: Strideable>(lhs: T, rhs: T.Stride)` where generic argument types depend on each other. I tried attacking that, but it was too big of a bite for me to manage all at once. But there are FIXME’s here to try that again at some point. New tests for SR-69 are at the end of deduction.swift, and the rest of the test changes are generally improved deduced diagnoses. I think the changed diagnoses in materializable_restrictions.swift is the only one which is worse instead of better, and that’s just because the previous general message mentioned `inout` basically accidentally. Opportunity for further improvement (a new diagnosis maybe) there. Validation tests run and passed.
25 lines
618 B
Swift
25 lines
618 B
Swift
// RUN: %target-parse-verify-swift
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func test15921520() {
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var x: Int = 0
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func f<T>(x: T) {} // expected-note{{in call to function 'f'}}
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f(&x) // expected-error{{generic parameter 'T' could not be inferred}}
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}
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func test20807269() {
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var x: Int = 0
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func f<T>(x: T) {}
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f(1, &x) // expected-error{{extra argument in call}}
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}
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func test15921530() {
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struct X {}
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func makef<T>() -> (T) -> () { // expected-note {{in call to function 'makef'}}
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return {
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x in ()
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}
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}
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var _: (inout X) -> () = makef() // expected-error{{generic parameter 'T' could not be inferred}}
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}
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