debuginfo: Variables in generic functions should have generic type. #8641

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michaelwoerister opened this Issue Aug 20, 2013 · 3 comments

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@michaelwoerister
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As per 3.3.7 Function Template Instantiations of the DWARF 4 specification, the template type parameter DIE (debug information entry) should be referenced where it has been used in the source code, as opposed to the DIE for the type that has been substituted for the parameter.

In the context of Rust this would mean that the variable x in the following function should be described as having type T=int instead of just type int:

fn generic_fun<T>(x: T) -> T {
    ...
}

fn main() {
    let s_have = Some(generic_fun(11111));
}

As of PR #8554 generic functions are supported but arguments, return value, locals, etc are described as having their type concrete type instead of "their generic type substituted by their concrete type". That means that debug info loses some information.

This should not pose a big problem to the regular debugging workflow---but I wanted to record somewhere that this issue exists.

@flaper87
Contributor

Visiting for triage. It still seems relevant.

@steveklabnik
Contributor

Triage: nothing to add.

@steveklabnik
Contributor

Triage: same as last year.

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