Apply suggestions from code review

Co-authored-by: Oli Scherer <[email protected]>

Author: cjgillot

compiler/rustc_hir/src/hir.rs

@@ -671,7 +671,7 @@ pub struct Crate<'hir> {
     pub attrs: BTreeMap<HirId, &'hir [Attribute]>,
 }
 
-impl<'hir> Crate<'hir> {
+impl Crate<'hir> {
     pub fn module(&self) -> &'hir Mod<'hir> {
         if let Some(OwnerNode::Crate(m)) = self.owners[CRATE_DEF_ID] { m } else { panic!() }
     }

compiler/rustc_middle/src/hir/map/mod.rs

@@ -160,7 +160,7 @@ impl<'hir> Map<'hir> {
     pub fn root_module(&self) -> &'hir Mod<'hir> {
         match self.tcx.hir_owner(CRATE_DEF_ID).map(|o| o.node) {
             Some(OwnerNode::Crate(item)) => item,
-            _ => panic!(),
+            _ => bug!(),
         }
     }