Cannot build with -g: dbg attachment points at wrong subprogram for function

[jonhoo]

Trying to compile the following code with -g fails on stable, beta, and nightly:

use std::collections::HashMap;

enum T {
    Some(i64),
    None,
}

impl T {
    fn x(&self, a: i64, b: &HashMap<i64, T>, c: Option<&HashMap<i64, i64>>) -> Vec<i64> {
        match *self {
            T::None => vec![a],
            _ if c.and_then(|c| c.get(&a)).is_some() => vec![a],
            T::Some(i) => b[&i].x(i, b, c),
        }
    }
}

fn main() {}

with the error

!dbg attachment points at wrong subprogram for function
!685 = distinct !DISubprogram(name: "fnfn", linkageName: "fnfn", scope: !328, file: !328, line: 12, type: !347, isLocal: true, isDefinition: true, scopeLine: 12, flags: DIFlagPrototyped, isOptimized: false, templateParams: !50, variables: !50)
i8* (i64, %"1.std::collections::hash::map::HashMap<i64, i64, std::collections::hash::map::RandomState>"*)* @"_ZN1T1x28_$u7b$$u7b$closure$u7d$$u7d$12closure.3923E"
  call void @llvm.dbg.declare(metadata %"1.std::collections::hash::map::HashMap<i64, i64, std::collections::hash::map::RandomState>"** %c, metadata !953, metadata !917), !dbg !954
!954 = !DILocation(line: 12, scope: !346)
!346 = distinct !DISubprogram(name: "fnfn", linkageName: "fnfn", scope: !328, file: !328, line: 12, type: !347, isLocal: true, isDefinition: true, scopeLine: 12, flags: DIFlagPrototyped, isOptimized: false, templateParams: !50, variables: !50)
!346 = distinct !DISubprogram(name: "fnfn", linkageName: "fnfn", scope: !328, file: !328, line: 12, type: !347, isLocal: true, isDefinition: true, scopeLine: 12, flags: DIFlagPrototyped, isOptimized: false, templateParams: !50, variables: !50)
LLVM ERROR: Broken function found, compilation aborted!

[jonhoo]

Don't know if this is related to #28947 or #29923.

[alexcrichton]

cc @michaelwoerister

[michaelwoerister]

Thanks for the bug report, @jonhoo!
At first glance this looks like an incarnation of #17201, which supposedly has been fixed. We'll need to take a look at the unoptimized LLVM IR to see if all calls are assigned a valid debug location.

[Mark-Simulacrum]

This no longer breaks. Closing.