add a try_structurally_resolve_type
in coerce
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parent
42067596c2
commit
d2c7449189
@ -1005,7 +1005,7 @@ pub fn try_coerce(
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allow_two_phase: AllowTwoPhase,
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cause: Option<ObligationCause<'tcx>>,
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) -> RelateResult<'tcx, Ty<'tcx>> {
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let source = self.resolve_vars_with_obligations(expr_ty);
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let source = self.try_structurally_resolve_type(expr.span, expr_ty);
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debug!("coercion::try({:?}: {:?} -> {:?})", expr, source, target);
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let cause =
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@ -1465,16 +1465,13 @@ fn add_required_obligations_with_code(
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}
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}
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/// Resolves `typ` by a single level if `typ` is a type variable.
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/// Try to resolve `ty` to a structural type, normalizing aliases.
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///
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/// When the new solver is enabled, this will also attempt to normalize
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/// the type if it's a projection (note that it will not deeply normalize
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/// projections within the type, just the outermost layer of the type).
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///
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/// If no resolution is possible, then an error is reported.
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/// Numeric inference variables may be left unresolved.
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pub fn structurally_resolve_type(&self, sp: Span, ty: Ty<'tcx>) -> Ty<'tcx> {
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let mut ty = self.resolve_vars_with_obligations(ty);
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/// In case there is still ambiguity, the returned type may be an inference
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/// variable. This is different from `structurally_resolve_type` which errors
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/// in this case.
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pub fn try_structurally_resolve_type(&self, sp: Span, ty: Ty<'tcx>) -> Ty<'tcx> {
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let ty = self.resolve_vars_with_obligations(ty);
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if self.next_trait_solver()
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&& let ty::Alias(ty::Projection, _) = ty.kind()
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@ -1483,15 +1480,27 @@ pub fn structurally_resolve_type(&self, sp: Span, ty: Ty<'tcx>) -> Ty<'tcx> {
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.at(&self.misc(sp), self.param_env)
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.structurally_normalize(ty, &mut **self.fulfillment_cx.borrow_mut())
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{
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Ok(normalized_ty) => {
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ty = normalized_ty;
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},
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Ok(normalized_ty) => normalized_ty,
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Err(errors) => {
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let guar = self.err_ctxt().report_fulfillment_errors(&errors);
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return self.tcx.ty_error(guar);
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}
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}
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}
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} else {
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ty
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}
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}
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/// Resolves `ty` by a single level if `ty` is a type variable.
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///
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/// When the new solver is enabled, this will also attempt to normalize
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/// the type if it's a projection (note that it will not deeply normalize
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/// projections within the type, just the outermost layer of the type).
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///
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/// If no resolution is possible, then an error is reported.
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/// Numeric inference variables may be left unresolved.
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pub fn structurally_resolve_type(&self, sp: Span, ty: Ty<'tcx>) -> Ty<'tcx> {
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let ty = self.try_structurally_resolve_type(sp, ty);
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if !ty.is_ty_var() {
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ty
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