incorrect DW_AT_location for static

[tromey]

I'm using rust from the Fedora COPR:

bapiya. rustc --version
rustc 1.7.0 (a5d1e7a59 2016-02-29)

Consider this program:

pub static AA: i32 = 5;

fn main() {
}

I compile with -g and then examine the DWARF using readelf. I see:

 <2><2f>: Abbrev Number: 3 (DW_TAG_variable)
    <30>   DW_AT_name        : (indirect string, offset: 0x48): AA
    <34>   DW_AT_type        : <0x62>
    <38>   DW_AT_decl_file   : 1
    <39>   DW_AT_decl_line   : 1
    <3a>   DW_AT_location    : 9 byte block: 3 0 0 0 0 0 0 0 0  (DW_OP_addr: 0)
    <44>   DW_AT_linkage_name: (indirect string, offset: 0x4f): _ZN2b12AAE

Now, this variable is not actually emitted. There's no ELF symbol for it. Given this, it seems strange to emit DW_AT_linkage_name and DW_AT_location, especially considering that the latter is incorrect.

[michaelwoerister]

Interesting. We are probably setting the static's linkage to private but don't take care of removing debuginfo for it and LLVM doesn't either.

[Mark-Simulacrum]

#33172 has good reproduction instructions.

[wesleywiser]

Visited in wg-debugging's triage meeting. This still repros in 2022 but since it's just a matter of including more info than necessary, we don't believe this is breaking any debuggers so marking as P-low.