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Some subst cleanup #96854

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merged 2 commits into from
May 9, 2022
Merged

Some subst cleanup #96854

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e14eae6
Remove subst_spanned
jackh726 May 9, 2022
657499d
Reorder erasing/replacing late bound vars and substs
jackh726 May 9, 2022
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48 changes: 10 additions & 38 deletions compiler/rustc_middle/src/ty/subst.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -10,7 +10,7 @@ use rustc_data_structures::intern::{Interned, WithStableHash};
use rustc_hir::def_id::DefId;
use rustc_macros::HashStable;
use rustc_serialize::{self, Decodable, Encodable};
use rustc_span::{Span, DUMMY_SP};
use rustc_span::DUMMY_SP;
use smallvec::SmallVec;

use core::intrinsics;
Expand Down Expand Up @@ -498,34 +498,14 @@ impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<Ty<'tcx>> {
}
}

///////////////////////////////////////////////////////////////////////////
// Public trait `Subst`
//
// Just call `foo.subst(tcx, substs)` to perform a substitution across
// `foo`. Or use `foo.subst_spanned(tcx, substs, Some(span))` when
// there is more information available (for better errors).

// Just call `foo.subst(tcx, substs)` to perform a substitution across `foo`.
pub trait Subst<'tcx>: Sized {
fn subst(self, tcx: TyCtxt<'tcx>, substs: &[GenericArg<'tcx>]) -> Self {
self.subst_spanned(tcx, substs, None)
}

fn subst_spanned(
self,
tcx: TyCtxt<'tcx>,
substs: &[GenericArg<'tcx>],
span: Option<Span>,
) -> Self;
fn subst(self, tcx: TyCtxt<'tcx>, substs: &[GenericArg<'tcx>]) -> Self;
}

impl<'tcx, T: TypeFoldable<'tcx>> Subst<'tcx> for T {
fn subst_spanned(
self,
tcx: TyCtxt<'tcx>,
substs: &[GenericArg<'tcx>],
span: Option<Span>,
) -> T {
let mut folder = SubstFolder { tcx, substs, span, binders_passed: 0 };
fn subst(self, tcx: TyCtxt<'tcx>, substs: &[GenericArg<'tcx>]) -> T {
let mut folder = SubstFolder { tcx, substs, binders_passed: 0 };
self.fold_with(&mut folder)
}
}
Expand All @@ -537,9 +517,6 @@ struct SubstFolder<'a, 'tcx> {
tcx: TyCtxt<'tcx>,
substs: &'a [GenericArg<'tcx>],

/// The location for which the substitution is performed, if available.
span: Option<Span>,

/// Number of region binders we have passed through while doing the substitution
binders_passed: u32,
}
Expand Down Expand Up @@ -571,13 +548,12 @@ impl<'a, 'tcx> TypeFolder<'tcx> for SubstFolder<'a, 'tcx> {
match rk {
Some(GenericArgKind::Lifetime(lt)) => self.shift_region_through_binders(lt),
_ => {
let span = self.span.unwrap_or(DUMMY_SP);
let msg = format!(
"Region parameter out of range \
when substituting in region {} (index={})",
data.name, data.index
);
span_bug!(span, "{}", msg);
span_bug!(DUMMY_SP, "{}", msg);
}
}
}
Expand Down Expand Up @@ -617,9 +593,8 @@ impl<'a, 'tcx> SubstFolder<'a, 'tcx> {
let ty = match opt_ty {
Some(GenericArgKind::Type(ty)) => ty,
Some(kind) => {
let span = self.span.unwrap_or(DUMMY_SP);
span_bug!(
span,
DUMMY_SP,
"expected type for `{:?}` ({:?}/{}) but found {:?} \
when substituting, substs={:?}",
p,
Expand All @@ -630,9 +605,8 @@ impl<'a, 'tcx> SubstFolder<'a, 'tcx> {
);
}
None => {
let span = self.span.unwrap_or(DUMMY_SP);
span_bug!(
span,
DUMMY_SP,
"type parameter `{:?}` ({:?}/{}) out of range \
when substituting, substs={:?}",
p,
Expand All @@ -652,9 +626,8 @@ impl<'a, 'tcx> SubstFolder<'a, 'tcx> {
let ct = match opt_ct {
Some(GenericArgKind::Const(ct)) => ct,
Some(kind) => {
let span = self.span.unwrap_or(DUMMY_SP);
span_bug!(
span,
DUMMY_SP,
"expected const for `{:?}` ({:?}/{}) but found {:?} \
when substituting substs={:?}",
p,
Expand All @@ -665,9 +638,8 @@ impl<'a, 'tcx> SubstFolder<'a, 'tcx> {
);
}
None => {
let span = self.span.unwrap_or(DUMMY_SP);
span_bug!(
span,
DUMMY_SP,
"const parameter `{:?}` ({:?}/{}) out of range \
when substituting substs={:?}",
p,
Expand Down
10 changes: 2 additions & 8 deletions compiler/rustc_typeck/src/astconv/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -523,11 +523,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
self.astconv
.normalize_ty(
self.span,
tcx.at(self.span).type_of(param.def_id).subst_spanned(
tcx,
substs,
Some(self.span),
),
tcx.at(self.span).type_of(param.def_id).subst(tcx, substs),
)
.into()
}
Expand All @@ -547,9 +543,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
GenericParamDefKind::Const { has_default } => {
let ty = tcx.at(self.span).type_of(param.def_id);
if !infer_args && has_default {
tcx.const_param_default(param.def_id)
.subst_spanned(tcx, substs.unwrap(), Some(self.span))
.into()
tcx.const_param_default(param.def_id).subst(tcx, substs.unwrap()).into()
} else {
if infer_args {
self.astconv.ct_infer(ty, Some(param), self.span).into()
Expand Down
9 changes: 2 additions & 7 deletions compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1403,10 +1403,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
// is missing.
let default = tcx.type_of(param.def_id);
self.fcx
.normalize_ty(
self.span,
default.subst_spanned(tcx, substs.unwrap(), Some(self.span)),
)
.normalize_ty(self.span, default.subst(tcx, substs.unwrap()))
.into()
} else {
// If no type arguments were provided, we have to infer them.
Expand All @@ -1418,9 +1415,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
}
GenericParamDefKind::Const { has_default } => {
if !infer_args && has_default {
tcx.const_param_default(param.def_id)
.subst_spanned(tcx, substs.unwrap(), Some(self.span))
.into()
tcx.const_param_default(param.def_id).subst(tcx, substs.unwrap()).into()
} else {
self.fcx.var_for_def(self.span, param)
}
Expand Down
16 changes: 5 additions & 11 deletions compiler/rustc_typeck/src/check/method/confirm.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -462,19 +462,13 @@ impl<'a, 'tcx> ConfirmContext<'a, 'tcx> {

let sig = self.tcx.fn_sig(def_id);

// Instantiate late-bound regions and substitute the trait
// parameters into the method type to get the actual method type.
//
// N.B., instantiate late-bound regions first so that
// `instantiate_type_scheme` can normalize associated types that
// may reference those regions.
let method_sig = self.replace_bound_vars_with_fresh_vars(sig);
debug!("late-bound lifetimes from method instantiated, method_sig={:?}", method_sig);
let sig = sig.subst(self.tcx, all_substs);
debug!("type scheme substituted, sig={:?}", sig);

let method_sig = method_sig.subst(self.tcx, all_substs);
debug!("type scheme substituted, method_sig={:?}", method_sig);
let sig = self.replace_bound_vars_with_fresh_vars(sig);
debug!("late-bound lifetimes from method instantiated, sig={:?}", sig);

(method_sig, method_predicates)
(sig, method_predicates)
}

fn add_obligations(
Expand Down
2 changes: 1 addition & 1 deletion compiler/rustc_typeck/src/check/method/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -461,8 +461,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
// `instantiate_type_scheme` can normalize associated types that
// may reference those regions.
let fn_sig = tcx.fn_sig(def_id);
let fn_sig = self.replace_bound_vars_with_fresh_vars(span, infer::FnCall, fn_sig).0;
let fn_sig = fn_sig.subst(self.tcx, substs);
let fn_sig = self.replace_bound_vars_with_fresh_vars(span, infer::FnCall, fn_sig).0;

let InferOk { value, obligations: o } = if is_op {
self.normalize_op_associated_types_in_as_infer_ok(span, fn_sig, opt_input_expr)
Expand Down
14 changes: 6 additions & 8 deletions compiler/rustc_typeck/src/check/method/probe.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1784,12 +1784,8 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
let generics = self.tcx.generics_of(method);
assert_eq!(substs.len(), generics.parent_count as usize);

// Erase any late-bound regions from the method and substitute
// in the values from the substitution.
let xform_fn_sig = self.erase_late_bound_regions(fn_sig);

if generics.params.is_empty() {
xform_fn_sig.subst(self.tcx, substs)
let xform_fn_sig = if generics.params.is_empty() {
fn_sig.subst(self.tcx, substs)
} else {
let substs = InternalSubsts::for_item(self.tcx, method, |param, _| {
let i = param.index as usize;
Expand All @@ -1807,8 +1803,10 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
}
}
});
xform_fn_sig.subst(self.tcx, substs)
}
fn_sig.subst(self.tcx, substs)
};

self.erase_late_bound_regions(xform_fn_sig)
}

/// Gets the type of an impl and generate substitutions with placeholders.
Expand Down