Fix line numbers for MIR inlined code

`should_collapse_debuginfo` detects if the specified span is part of a
macro expansion however it does this by checking if the span is anything
other than a normal (non-expanded) kind, then the span sequence is
walked backwards to the root span.

This doesn't work when the MIR inliner inlines code as it creates spans
with expansion information set to `ExprKind::Inlined` and results in the
line number being attributed to the inline callsite rather than the
normal line number of the inlined code.

1 files changed, 3 insertions, 1 deletions

diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs
index 0d7d4054bb3..34938ab05cb 100644
--- a/compiler/rustc_middle/src/ty/mod.rs
+++ b/compiler/rustc_middle/src/ty/mod.rs
@@ -2522,7 +2522,9 @@ impl<'tcx> TyCtxt<'tcx> {
             && if self.features().collapse_debuginfo {
                 span.in_macro_expansion_with_collapse_debuginfo()
             } else {
-                span.from_expansion()
+                // Inlined spans should not be collapsed as that leads to all of the
+                // inlined code being attributed to the inline callsite.
+                span.from_expansion() && !span.is_inlined()
             }
     }