refactor type_of for consts

Author: lcnr

src/librustc_typeck/collect/type_of.rs

@@ -216,93 +216,87 @@ pub(super) fn type_of(tcx: TyCtxt<'_>, def_id: DefId) -> Ty<'_> {
  | Node::Expr(&Expr { kind: ExprKind::Path(_), .. })
  | Node::TraitRef(..) => {
  let path = match parent_node {
- Node::Ty(&Ty {
- kind: TyKind::Path(QPath::Resolved(_, ref path)), ..
- })
+ Node::Ty(&Ty { kind: TyKind::Path(QPath::Resolved(_, path)), .. })
  | Node::Expr(&Expr {
- kind: ExprKind::Path(QPath::Resolved(_, ref path)),
+ kind:
+ ExprKind::Path(QPath::Resolved(_, path))
+ | ExprKind::Struct(&QPath::Resolved(_, path), ..),
  ..
- }) => Some(&**path),
- Node::Expr(&Expr { kind: ExprKind::Struct(ref path, ..), .. }) => {
- if let QPath::Resolved(_, ref path) = **path {
- Some(&**path)
- } else {
- None
- }
+ })
+ | Node::TraitRef(&TraitRef { path, .. }) => &*path,
+ _ => {
+ tcx.sess.delay_span_bug(
+ DUMMY_SP,
+ &format!("unexpected const parent path {:?}", parent_node),
+ );
+ return tcx.types.err;
  }
- Node::TraitRef(&TraitRef { ref path, .. }) => Some(&**path),
- _ => None,
  };
 
- if let Some(path) = path {
- // We've encountered an `AnonConst` in some path, so we need to
- // figure out which generic parameter it corresponds to and return
- // the relevant type.
-
- let (arg_index, segment) = path
- .segments
- .iter()
- .filter_map(|seg| seg.args.as_ref().map(|args| (args.args, seg)))
- .find_map(|(args, seg)| {
- args.iter()
- .filter(|arg| arg.is_const())
- .enumerate()
- .filter(|(_, arg)| arg.id() == hir_id)
- .map(|(index, _)| (index, seg))
- .next()
- })
- .unwrap_or_else(|| {
- bug!("no arg matching AnonConst in path");
- });
-
- // Try to use the segment resolution if it is valid, otherwise we
- // default to the path resolution.
- let res = segment.res.filter(|&r| r != Res::Err).unwrap_or(path.res);
- let generics = match res {
- Res::Def(DefKind::Ctor(..), def_id) => {
- tcx.generics_of(tcx.parent(def_id).unwrap())
- }
- Res::Def(_, def_id) => tcx.generics_of(def_id),
- res => {
- tcx.sess.delay_span_bug(
- DUMMY_SP,
- &format!(
- "unexpected anon const res {:?} in path: {:?}",
- res, path,
- ),
- );
- return tcx.types.err;
+ // We've encountered an `AnonConst` in some path, so we need to
+ // figure out which generic parameter it corresponds to and return
+ // the relevant type.
+
+ let (arg_index, segment) = path
+ .segments
+ .iter()
+ .filter_map(|seg| seg.args.as_ref().map(|args| (args.args, seg)))
+ .find_map(|(args, seg)| {
+ args.iter()
+ .filter(|arg| arg.is_const())
+ .enumerate()
+ .filter(|(_, arg)| arg.id() == hir_id)
+ .map(|(index, _)| (index, seg))
+ .next()
+ })
+ .unwrap_or_else(|| {
+ bug!("no arg matching AnonConst in path");
+ });
+
+ // Try to use the segment resolution if it is valid, otherwise we
+ // default to the path resolution.
+ let res = segment.res.filter(|&r| r != Res::Err).unwrap_or(path.res);
+ let generics = match res {
+ Res::Def(DefKind::Ctor(..), def_id) => {
+ tcx.generics_of(tcx.parent(def_id).unwrap())
+ }
+ Res::Def(_, def_id) => tcx.generics_of(def_id),
+ res => {
+ tcx.sess.delay_span_bug(
+ DUMMY_SP,
+ &format!(
+ "unexpected anon const res {:?} in path: {:?}",
+ res, path,
+ ),
+ );
+ return tcx.types.err;
+ }
+ };
+
+ let ty = generics
+ .params
+ .iter()
+ .filter(|param| {
+ if let ty::GenericParamDefKind::Const = param.kind {
+ true
+ } else {
+ false
  }
- };
+ })
+ .nth(arg_index)
+ .map(|param| tcx.type_of(param.def_id));
 
- generics
- .params
- .iter()
- .filter(|param| {
- if let ty::GenericParamDefKind::Const = param.kind {
- true
- } else {
- false
- }
- })
- .nth(arg_index)
- .map(|param| tcx.type_of(param.def_id))
- // This is no generic parameter associated with the arg. This is
- // probably from an extra arg where one is not needed.
- .unwrap_or_else(|| {
- tcx.sess.delay_span_bug(
- DUMMY_SP,
- &format!(
- "missing generic parameter for `AnonConst`, parent: {:?}, res: {:?}",
- parent_node, res
- ),
- );
- tcx.types.err
- })
+ if let Some(ty) = ty {
+ ty
  } else {
+ // This is no generic parameter associated with the arg. This is
+ // probably from an extra arg where one is not needed.
  tcx.sess.delay_span_bug(
  DUMMY_SP,
- &format!("unexpected const parent path {:?}", parent_node,),
+ &format!(
+ "missing generic parameter for `AnonConst`, parent: {:?}, res: {:?}",
+ parent_node, res
+ ),
  );
  tcx.types.err
  }