save-analysis: handle type defs in struct patterns

[nrc]

r? @huonw

[nrc]

rebased

ping @huonw for review

[huonw]

I'm struggling to understand the background for this patch. What's a code example that this change fixes/improves?

[nrc]

impl Foo for i32 {} In that case we fall into the first branch of the match, but looking up the type definition gives us None, this makes sure we register the fact that there is an impl of Foo in this case (as well as the trait reference).

[huonw]

That sounds like a case for #22691?

[nrc]

oh, right, sorry, got confused between the two.

The use case for this is something like:

struct Foo {
a: i32,
}
type Bar = Foo;
fn baz(Bar { a }: Bar) {
}

Previously, this crashed in save-analysis. Now it works.

[huonw]

@bors r+ 6f9b rollup