Auto merge of #76931 - oli-obk:const_prop_inline_lint_madness, r=wesleywiser

Properly handle lint spans after MIR inlining

The first commit shows what happens when we apply mir inlining and then cause lints on the inlined MIR.
The second commit fixes that.

r? `@wesleywiser`

compiler/rustc_span/src/hygiene.rs

@@ -766,6 +766,8 @@ pub enum ExpnKind {
     AstPass(AstPass),
     /// Desugaring done by the compiler during HIR lowering.
     Desugaring(DesugaringKind),
+    /// MIR inlining
+    Inlined,
 }
 
 impl ExpnKind {
@@ -779,6 +781,7 @@ impl ExpnKind {
             },
             ExpnKind::AstPass(kind) => kind.descr().to_string(),
             ExpnKind::Desugaring(kind) => format!("desugaring of {}", kind.descr()),
+            ExpnKind::Inlined => "inlined source".to_string(),
         }
     }
 }