use ty::fold::TypeFoldable;
use ty::subst::Subst;
-use infer::{InferCtxt, InferOk};
+use infer::{InferOk};
/// Whether we do the orphan check relative to this crate or
/// to some remote crate.
pub intercrate_ambiguity_causes: Vec<IntercrateAmbiguityCause>,
}
-/// If there are types that satisfy both impls, returns a suitably-freshened
-/// `ImplHeader` with those types substituted
-pub fn overlapping_impls<'cx, 'gcx, 'tcx>(infcx: &InferCtxt<'cx, 'gcx, 'tcx>,
- impl1_def_id: DefId,
- impl2_def_id: DefId,
- intercrate_mode: IntercrateMode)
- -> Option<OverlapResult<'tcx>>
+/// If there are types that satisfy both impls, invokes `on_overlap`
+/// with a suitably-freshened `ImplHeader` with those types
+/// substituted. Otherwise, invokes `no_overlap`.
+pub fn overlapping_impls<'gcx, F1, F2, R>(
+ tcx: TyCtxt<'_, 'gcx, 'gcx>,
+ impl1_def_id: DefId,
+ impl2_def_id: DefId,
+ intercrate_mode: IntercrateMode,
+ on_overlap: F1,
+ no_overlap: F2,
+) -> R
+where
+ F1: FnOnce(OverlapResult<'_>) -> R,
+ F2: FnOnce() -> R,
{
debug!("impl_can_satisfy(\
impl1_def_id={:?}, \
impl2_def_id,
intercrate_mode);
- let selcx = &mut SelectionContext::intercrate(infcx, intercrate_mode);
- overlap(selcx, impl1_def_id, impl2_def_id)
+ let overlaps = tcx.infer_ctxt().enter(|infcx| {
+ let selcx = &mut SelectionContext::intercrate(&infcx, intercrate_mode);
+ overlap(selcx, impl1_def_id, impl2_def_id).is_some()
+ });
+
+ if !overlaps {
+ return no_overlap();
+ }
+
+ // In the case where we detect an error, run the check again, but
+ // this time tracking intercrate ambuiguity causes for better
+ // diagnostics. (These take time and can lead to false errors.)
+ tcx.infer_ctxt().enter(|infcx| {
+ let selcx = &mut SelectionContext::intercrate(&infcx, intercrate_mode);
+ selcx.enable_tracking_intercrate_ambiguity_causes();
+ on_overlap(overlap(selcx, impl1_def_id, impl2_def_id).unwrap())
+ })
}
fn with_fresh_ty_vars<'cx, 'gcx, 'tcx>(selcx: &mut SelectionContext<'cx, 'gcx, 'tcx>,
return None
}
- Some(OverlapResult {
- impl_header: selcx.infcx().resolve_type_vars_if_possible(&a_impl_header),
- intercrate_ambiguity_causes: selcx.intercrate_ambiguity_causes().to_vec(),
- })
+ let impl_header = selcx.infcx().resolve_type_vars_if_possible(&a_impl_header);
+ let intercrate_ambiguity_causes = selcx.take_intercrate_ambiguity_causes();
+ debug!("overlap: intercrate_ambiguity_causes={:#?}", intercrate_ambiguity_causes);
+ Some(OverlapResult { impl_header, intercrate_ambiguity_causes })
}
pub fn trait_ref_is_knowable<'a, 'gcx, 'tcx>(tcx: TyCtxt<'a, 'gcx, 'tcx>,