diff --git a/src/librustc_typeck/check/mod.rs b/src/librustc_typeck/check/mod.rs
index 5273b022ad2..ae4cb48b7c6 100644
--- a/src/librustc_typeck/check/mod.rs
+++ b/src/librustc_typeck/check/mod.rs
@@ -2007,37 +2007,10 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
// we will rollback the inference context to its prior state so we can probe
// for conflicts and correctly report them.
-
let _ = self.commit_if_ok(|_: &infer::CombinedSnapshot| {
- for ty in &unbound_tyvars {
- if self.type_var_diverges(ty) {
- self.demand_eqtype(syntax_pos::DUMMY_SP, *ty,
- self.tcx.mk_diverging_default());
- } else {
- match self.type_is_unconstrained_numeric(ty) {
- UnconstrainedInt => {
- self.demand_eqtype(syntax_pos::DUMMY_SP, *ty, self.tcx.types.i32)
- },
- UnconstrainedFloat => {
- self.demand_eqtype(syntax_pos::DUMMY_SP, *ty, self.tcx.types.f64)
- }
- Neither => {
- if let Some(default) = default_map.get(ty) {
- let default = default.clone();
- let default_ty = self.normalize_associated_types_in(
- default.origin_span, &default.ty);
- match self.eq_types(false,
- &self.misc(default.origin_span),
- ty,
- default_ty) {
- Ok(ok) => self.register_infer_ok_obligations(ok),
- Err(_) => conflicts.push((*ty, default)),
- }
- }
- }
- }
- }
- }
+ conflicts.extend(
+ self.apply_defaults_and_return_conflicts(&unbound_tyvars, &default_map, None)
+ );
// If there are conflicts we rollback, otherwise commit
if conflicts.len() > 0 {
@@ -2047,37 +2020,41 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
}
});
- if conflicts.len() > 0 {
- // Loop through each conflicting default, figuring out the default that caused
- // a unification failure and then report an error for each.
- for (conflict, default) in conflicts {
- let conflicting_default =
- self.find_conflicting_default(&unbound_tyvars, &default_map, conflict)
- .unwrap_or(type_variable::Default {
- ty: self.next_ty_var(
- TypeVariableOrigin::MiscVariable(syntax_pos::DUMMY_SP)),
- origin_span: syntax_pos::DUMMY_SP,
- // what do I put here?
- def_id: self.tcx.hir.local_def_id(ast::CRATE_NODE_ID)
- });
+ // Loop through each conflicting default, figuring out the default that caused
+ // a unification failure and then report an error for each.
+ for (conflict, default) in conflicts {
+ let conflicting_default =
+ self.apply_defaults_and_return_conflicts(
+ &unbound_tyvars,
+ &default_map,
+ Some(conflict)
+ )
+ .last()
+ .map(|(_, tv)| tv)
+ .unwrap_or(type_variable::Default {
+ ty: self.next_ty_var(
+ TypeVariableOrigin::MiscVariable(syntax_pos::DUMMY_SP)),
+ origin_span: syntax_pos::DUMMY_SP,
+ // what do I put here?
+ def_id: self.tcx.hir.local_def_id(ast::CRATE_NODE_ID)
+ });
- // This is to ensure that we elimnate any non-determinism from the error
- // reporting by fixing an order, it doesn't matter what order we choose
- // just that it is consistent.
- let (first_default, second_default) =
- if default.def_id < conflicting_default.def_id {
- (default, conflicting_default)
- } else {
- (conflicting_default, default)
- };
+ // This is to ensure that we elimnate any non-determinism from the error
+ // reporting by fixing an order, it doesn't matter what order we choose
+ // just that it is consistent.
+ let (first_default, second_default) =
+ if default.def_id < conflicting_default.def_id {
+ (default, conflicting_default)
+ } else {
+ (conflicting_default, default)
+ };
- self.report_conflicting_default_types(
- first_default.origin_span,
- self.body_id,
- first_default,
- second_default)
- }
+ self.report_conflicting_default_types(
+ first_default.origin_span,
+ self.body_id,
+ first_default,
+ second_default)
}
}
@@ -2088,39 +2065,29 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
// apply the default that caused conflict first to a local version of the type variable
// table then apply defaults until we find a conflict. That default must be the one
// that caused conflict earlier.
- fn find_conflicting_default(&self,
- unbound_vars: &FxHashSet<Ty<'tcx>>,
- default_map: &FxHashMap<&Ty<'tcx>, type_variable::Default<'tcx>>,
- conflict: Ty<'tcx>)
- -> Option<type_variable::Default<'tcx>> {
+ fn apply_defaults_and_return_conflicts<'b>(
+ &'b self,
+ unbound_vars: &'b FxHashSet<Ty<'tcx>>,
+ default_map: &'b FxHashMap<&'b Ty<'tcx>, type_variable::Default<'tcx>>,
+ conflict: Option<Ty<'tcx>>,
+ ) -> impl Iterator<Item=(Ty<'tcx>, type_variable::Default<'tcx>)> + 'b {
use rustc::ty::error::UnconstrainedNumeric::Neither;
use rustc::ty::error::UnconstrainedNumeric::{UnconstrainedInt, UnconstrainedFloat};
- // Ensure that we apply the conflicting default first
- let mut unbound_tyvars = Vec::with_capacity(unbound_vars.len() + 1);
- unbound_tyvars.push(conflict);
- unbound_tyvars.extend(unbound_vars.iter());
-
- let mut result = None;
- // We run the same code as above applying defaults in order, this time when
- // we find the conflict we just return it for error reporting above.
-
- // We also run this inside snapshot that never commits so we can do error
- // reporting for more then one conflict.
- for ty in &unbound_tyvars {
+ conflict.into_iter().chain(unbound_vars.iter().cloned()).flat_map(move |ty| {
if self.type_var_diverges(ty) {
- self.demand_eqtype(syntax_pos::DUMMY_SP, *ty,
+ self.demand_eqtype(syntax_pos::DUMMY_SP, ty,
self.tcx.mk_diverging_default());
} else {
match self.type_is_unconstrained_numeric(ty) {
UnconstrainedInt => {
- self.demand_eqtype(syntax_pos::DUMMY_SP, *ty, self.tcx.types.i32)
+ self.demand_eqtype(syntax_pos::DUMMY_SP, ty, self.tcx.types.i32)
},
UnconstrainedFloat => {
- self.demand_eqtype(syntax_pos::DUMMY_SP, *ty, self.tcx.types.f64)
+ self.demand_eqtype(syntax_pos::DUMMY_SP, ty, self.tcx.types.f64)
},
Neither => {
- if let Some(default) = default_map.get(ty) {
+ if let Some(default) = default_map.get(&ty) {
let default = default.clone();
let default_ty = self.normalize_associated_types_in(
default.origin_span, &default.ty);
@@ -2130,16 +2097,16 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
default_ty) {
Ok(ok) => self.register_infer_ok_obligations(ok),
Err(_) => {
- result = Some(default);
+ return Some((ty, default));
}
}
}
}
}
}
- }
- return result;
+ None
+ })
}
fn select_all_obligations_or_error(&self) {