Incomplete save-analysis for macros

[DanielJCampbell]

Currently macros are only recorded if they are called at some point in non-generated source code. The most notable effect of this is that if a macro references some other macro internally (eg. foo! expands to bar!), that macro will not be indexed.

A fix probably requires changes to expansion traces, to store more information about macro bodies after expansion, or manually pulling nested macro calls out of callee spans.

[Mark-Simulacrum]

Test case for future visits:

macro_rules! a {
    () => {
        macro_rules! b {
            () => {
                0
            };
        }
        b!()
    }
}

fn main() {
    a!();
}

rustc -Z save-analysis test.rs
rg '"name":"b"' save-analysis-temp/test.json # should find "b"

[steveklabnik]

Triage: no change

[jyn514]

Save-analysis has been removed from the compiler.