Use span_bug instead of panic

Author: spastorino

compiler/rustc_ast_lowering/src/lib.rs

@@ -56,6 +56,7 @@ use rustc_hir::def_id::{LocalDefId, CRATE_DEF_ID};
 use rustc_hir::definitions::DefPathData;
 use rustc_hir::{ConstArg, GenericArg, ItemLocalId, ParamName, TraitCandidate};
 use rustc_index::vec::{Idx, IndexVec};
+use rustc_middle::span_bug;
 use rustc_middle::ty::{ResolverAstLowering, TyCtxt};
 use rustc_session::parse::feature_err;
 use rustc_span::hygiene::MacroKind;
@@ -1575,10 +1576,13 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
 
                 LifetimeRes::Static | LifetimeRes::Error => {}
 
-                res => panic!(
-                    "Unexpected lifetime resolution {:?} for {:?} at {:?}",
-                    res, lifetime.ident, lifetime.ident.span
-                ),
+                res => {
+                    let bug_msg = format!(
+                        "Unexpected lifetime resolution {:?} for {:?} at {:?}",
+                        res, lifetime.ident, lifetime.ident.span
+                    );
+                    span_bug!(lifetime.ident.span, "{}", bug_msg);
+                }
             }
         }