diff options
| -rw-r--r-- | src/librustc/infer/mod.rs | 59 |
1 files changed, 59 insertions, 0 deletions
diff --git a/src/librustc/infer/mod.rs b/src/librustc/infer/mod.rs index ef9886e06d4..cbfdf58adee 100644 --- a/src/librustc/infer/mod.rs +++ b/src/librustc/infer/mod.rs @@ -1230,6 +1230,65 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> { self.inlined_shallow_resolve(typ) } + /// A hacky sort of method used by the NLL type-relating code: + /// + /// - `var` must be some unbound type variable. + /// - `value` must be a suitable type to use as its value. + /// + /// `var` will then be equated with `value`. Note that this + /// sidesteps a number of important checks, such as the "occurs + /// check" that prevents cyclic types, so it is important not to + /// use this method during regular type-check. + pub fn force_instantiate_unchecked(&self, var: Ty<'tcx>, value: Ty<'tcx>) { + match (&var.sty, &value.sty) { + (&ty::Infer(ty::TyVar(vid)), _) => { + let mut type_variables = self.type_variables.borrow_mut(); + + // In NLL, we don't have type inference variables + // floating around, so we can do this rather imprecise + // variant of the occurs-check. + assert!(!value.has_infer_types()); + + type_variables.instantiate(vid, value); + } + + (&ty::Infer(ty::IntVar(vid)), &ty::Int(value)) => { + let mut int_unification_table = self.int_unification_table.borrow_mut(); + int_unification_table + .unify_var_value(vid, Some(ty::IntVarValue::IntType(value))) + .unwrap_or_else(|_| { + bug!("failed to unify int var `{:?}` with `{:?}`", vid, value); + }); + } + + (&ty::Infer(ty::IntVar(vid)), &ty::Uint(value)) => { + let mut int_unification_table = self.int_unification_table.borrow_mut(); + int_unification_table + .unify_var_value(vid, Some(ty::IntVarValue::UintType(value))) + .unwrap_or_else(|_| { + bug!("failed to unify int var `{:?}` with `{:?}`", vid, value); + }); + } + + (&ty::Infer(ty::FloatVar(vid)), &ty::Float(value)) => { + let mut float_unification_table = self.float_unification_table.borrow_mut(); + float_unification_table + .unify_var_value(vid, Some(ty::FloatVarValue(value))) + .unwrap_or_else(|_| { + bug!("failed to unify float var `{:?}` with `{:?}`", vid, value) + }); + } + + _ => { + bug!( + "force_instantiate_unchecked invoked with bad combination: var={:?} value={:?}", + var, + value, + ); + } + } + } + pub fn resolve_type_vars_if_possible<T>(&self, value: &T) -> T where T: TypeFoldable<'tcx>, |