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b1e5dd605a
fixes #18125 Previously a tuple type like `(T, int)` would match an expected tuple type `(U, int)` if `T` is a subtype of `U`. This is wrong since the codegen does not handle type conversions of individual tuple elements in a type conversion of an entire tuple. For this reason the compiler already does not accept `(float, int)` for a matched type `(int, int)`, however the code that checked for which relations are unacceptable checked for `< isSubtype` rather than `<= isSubtype`, so subtypes were not included in the unacceptable relations. Update: Now only considered unacceptable when inheritance is used, as in [`paramTypesMatch`](3379d26629/compiler/sigmatch.nim (L2252-L2254)). Ideally subtype relations that don't need conversions, like `nil`, `seq[empty]`, `range[0..5]` etc would be their own relation `isConcreteSubtype` (which would also allow us to differentiate with `openArray[T]`), but this is too big of a refactor for now. To compensate for this making things like `let x: (Parent, int) = (Child(), 0)` not compile (they would crash codegen before anyway but should still work in principle), type inference for tuple constructors is updated such that they call `fitNode` on the fields and their expected types, so a type conversion is generated for the individual subtype element. (cherry picked from commitcfd69bad1a)