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Unable to infer types correctly from generic on function #26418
Description
TypeScript Version: 3.0.1-insiders.20180726 (typescript playground version)
Search Terms:
generic, inference
Code
Note: noImplicitAny set to true
class BaseClass<P = any> {
public props: P;
}
function w<W extends BaseClass>(
ctr: (new () => W),
props: W['props']
) { }
interface MyClassProps {
myFunc(options: { foo: string }): void;
}
class MyClass extends BaseClass<MyClassProps> {}
// eplicit passing the generic
w<MyClass>(MyClass, {
myFunc(options) {
options.foo; // correctly infers prop
options.bar; // correctly errors
}
});
// inferring `myFunc` sig types based on `MyClass` argument
w(MyClass, {
myFunc(options) { // doesn't infer argument type
options.foo;
options.bar;
}
});Expected behavior:
Expected the argument of the function to be inferred correctly.
Actual behavior:
Doesn't infer the argument type or provide auto complete on the props of the w() function (does however type check)
Related Issues: Possibly related to #14829?
Activity
RyanCavanaugh commentedon Aug 13, 2018
Generic inference is a single-pass process; inferring a type for
optionshere would require a process of an arbitrary number of passes.#14829 wouldn't fix this on its own, but it'd be a prerequisite for deferring applying a type to the
optionsparameter to allow a contextual type fromTto be present.agubler commentedon Aug 13, 2018
Thanks for the response Ryan Cavanaugh (@RyanCavanaugh), glad that I’m not just doing something silly!
agubler commentedon Feb 20, 2019
Ryan Cavanaugh (@RyanCavanaugh) Interestingly using
tsxwith the following a simple globalJSXnamespacethe properties and any function arguments are all inferred correctly:
I guess this is because something "special" is happening?