Auto merge of #64474 - Mark-Simulacrum:permit-err-overlap, r=matthewjasper
Permit impls referencing errors to overlap
Fixes #43400; previously this would emit an overlapping impls error, but no longer does.
diff --git a/src/librustc/ty/mod.rs b/src/librustc/ty/mod.rs
index 41e4295..17eb4a8 100644
--- a/src/librustc/ty/mod.rs
+++ b/src/librustc/ty/mod.rs
@@ -2894,6 +2894,13 @@
pub fn impls_are_allowed_to_overlap(self, def_id1: DefId, def_id2: DefId)
-> Option<ImplOverlapKind>
{
+ // If either trait impl references an error, they're allowed to overlap,
+ // as one of them essentially doesn't exist.
+ if self.impl_trait_ref(def_id1).map_or(false, |tr| tr.references_error()) ||
+ self.impl_trait_ref(def_id2).map_or(false, |tr| tr.references_error()) {
+ return Some(ImplOverlapKind::Permitted);
+ }
+
let is_legit = if self.features().overlapping_marker_traits {
let trait1_is_empty = self.impl_trait_ref(def_id1)
.map_or(false, |trait_ref| {
diff --git a/src/test/ui/coherence/conflicting-impl-with-err.rs b/src/test/ui/coherence/conflicting-impl-with-err.rs
new file mode 100644
index 0000000..3e0234b
--- /dev/null
+++ b/src/test/ui/coherence/conflicting-impl-with-err.rs
@@ -0,0 +1,16 @@
+struct ErrorKind;
+struct Error(ErrorKind);
+
+impl From<nope::Thing> for Error { //~ ERROR failed to resolve
+ fn from(_: nope::Thing) -> Self { //~ ERROR failed to resolve
+ unimplemented!()
+ }
+}
+
+impl From<ErrorKind> for Error {
+ fn from(_: ErrorKind) -> Self {
+ unimplemented!()
+ }
+}
+
+fn main() {}
diff --git a/src/test/ui/coherence/conflicting-impl-with-err.stderr b/src/test/ui/coherence/conflicting-impl-with-err.stderr
new file mode 100644
index 0000000..a8a5730
--- /dev/null
+++ b/src/test/ui/coherence/conflicting-impl-with-err.stderr
@@ -0,0 +1,15 @@
+error[E0433]: failed to resolve: use of undeclared type or module `nope`
+ --> $DIR/conflicting-impl-with-err.rs:4:11
+ |
+LL | impl From<nope::Thing> for Error {
+ | ^^^^ use of undeclared type or module `nope`
+
+error[E0433]: failed to resolve: use of undeclared type or module `nope`
+ --> $DIR/conflicting-impl-with-err.rs:5:16
+ |
+LL | fn from(_: nope::Thing) -> Self {
+ | ^^^^ use of undeclared type or module `nope`
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0433`.
