bjoernager/rust
bjoernager/rust
1
Fork 0
Code Activity

update infer cost computation for types

Browse source
This commit is contained in:
lcnr 2022-07-01 14:09:33 +02:00
parent c2ed08715b
commit f1836c453a
6 changed files with 101 additions and 37 deletions
Download patch file Download diff file Expand all files Collapse all files

62
compiler/rustc_infer/src/infer/error_reporting/need_type_info.rs
View file

@ -602,41 +602,58 @@ impl<'a, 'tcx> FindInferSourceVisitor<'a, 'tcx> {
/// Sources with a small cost are prefer and should result
/// in a clearer and idiomatic suggestion.
fn source_cost(&self, source: &InferSource<'tcx>) -> usize {
let tcx = self.infcx.tcx;
fn arg_cost<'tcx>(arg: GenericArg<'tcx>) -> usize {
match arg.unpack() {
GenericArgKind::Lifetime(_) => 0, // erased
GenericArgKind::Type(ty) => ty_cost(ty),
GenericArgKind::Const(_) => 3, // some non-zero value
}
#[derive(Clone, Copy)]
struct CostCtxt<'tcx> {
tcx: TyCtxt<'tcx>,
}
fn ty_cost<'tcx>(ty: Ty<'tcx>) -> usize {
match ty.kind() {
ty::Closure(..) => 100,
ty::FnDef(..) => 20,
ty::FnPtr(..) => 10,
ty::Infer(..) => 0,
_ => 1,
impl<'tcx> CostCtxt<'tcx> {
fn arg_cost(self, arg: GenericArg<'tcx>) -> usize {
match arg.unpack() {
GenericArgKind::Lifetime(_) => 0, // erased
GenericArgKind::Type(ty) => self.ty_cost(ty),
GenericArgKind::Const(_) => 3, // some non-zero value
}
}
fn ty_cost(self, ty: Ty<'tcx>) -> usize {
match ty.kind() {
ty::Closure(..) => 1000,
ty::FnDef(..) => 150,
ty::FnPtr(..) => 30,
ty::Adt(def, substs) => {
5 + self
.tcx
.generics_of(def.did())
.own_substs_no_defaults(self.tcx, substs)
.iter()
.map(|&arg| self.arg_cost(arg))
.sum::<usize>()
}
ty::Tuple(args) => 5 + args.iter().map(|arg| self.ty_cost(arg)).sum::<usize>(),
ty::Infer(..) => 0,
_ => 1,
}
}
}
// The sources are listed in order of preference here.
let tcx = self.infcx.tcx;
let ctx = CostCtxt { tcx };
match source.kind {
InferSourceKind::LetBinding { ty, .. } => ty_cost(ty),
InferSourceKind::ClosureArg { ty, .. } => 5 + ty_cost(ty),
InferSourceKind::LetBinding { ty, .. } => ctx.ty_cost(ty),
InferSourceKind::ClosureArg { ty, .. } => ctx.ty_cost(ty),
InferSourceKind::GenericArg { def_id, generic_args, .. } => {
let variant_cost = match tcx.def_kind(def_id) {
DefKind::Variant | DefKind::Ctor(CtorOf::Variant, _) => 15, // `None::<u32>` and friends are ugly.
_ => 12,
// `None::<u32>` and friends are ugly.
DefKind::Variant | DefKind::Ctor(CtorOf::Variant, _) => 15,
_ => 10,
};
variant_cost + generic_args.iter().map(|&arg| arg_cost(arg)).sum::<usize>()
variant_cost + generic_args.iter().map(|&arg| ctx.arg_cost(arg)).sum::<usize>()
}
InferSourceKind::FullyQualifiedMethodCall { substs, .. } => {
20 + substs.iter().map(|arg| arg_cost(arg)).sum::<usize>()
20 + substs.iter().map(|arg| ctx.arg_cost(arg)).sum::<usize>()
}
InferSourceKind::ClosureReturn { ty, should_wrap_expr, .. } => {
30 + ty_cost(ty) + if should_wrap_expr.is_some() { 10 } else { 0 }
30 + ctx.ty_cost(ty) + if should_wrap_expr.is_some() { 10 } else { 0 }
}
}
}
@ -646,6 +663,7 @@ impl<'a, 'tcx> FindInferSourceVisitor<'a, 'tcx> {
#[instrument(level = "debug", skip(self))]
fn update_infer_source(&mut self, new_source: InferSource<'tcx>) {
let cost = self.source_cost(&new_source) + self.attempt;
debug!(?cost);
self.attempt += 1;
if cost < self.infer_source_cost {
self.infer_source_cost = cost;