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authorManish Goregaokar <manishsmail@gmail.com>2020-07-19 19:12:37 -0700
committerGitHub <noreply@github.com>2020-07-19 19:12:37 -0700
commit55c4057f55bac2c0f3a21fc82b4e28c12f5d85d3 (patch)
tree6573a846f530faf2b1a95f4cf2b72915037b186a
parent3981386b8e80e3ce35e70ffdac303c75d3771ea4 (diff)
parent455e6140d81f48d99d43573382c67f804434a949 (diff)
downloadrust-55c4057f55bac2c0f3a21fc82b4e28c12f5d85d3.tar.gz
rust-55c4057f55bac2c0f3a21fc82b4e28c12f5d85d3.zip
Rollup merge of #74516 - lcnr:min-specialization-ice, r=matthewjasper
do not try fetching the ancestors of errored trait impls

fixes #74483

While building the specialization graph, we use `tcx.all_impls` which discards impls with incorrect self types,
we do however call `trait_def.ancestors` with these impls which caused an ICE as they aren't part of the
specialization graph.
-rw-r--r--src/librustc_middle/traits/specialization_graph.rs4
-rw-r--r--src/test/ui/specialization/min_specialization/impl-on-nonexisting.rs7
-rw-r--r--src/test/ui/specialization/min_specialization/impl-on-nonexisting.stderr9
3 files changed, 19 insertions, 1 deletions
diff --git a/src/librustc_middle/traits/specialization_graph.rs b/src/librustc_middle/traits/specialization_graph.rs
index f4961617b81..c9aae898007 100644
--- a/src/librustc_middle/traits/specialization_graph.rs
+++ b/src/librustc_middle/traits/specialization_graph.rs
@@ -1,5 +1,6 @@
 use crate::ich::{self, StableHashingContext};
 use crate::ty::fast_reject::SimplifiedType;
+use crate::ty::fold::TypeFoldable;
 use crate::ty::{self, TyCtxt};
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
@@ -226,7 +227,8 @@ pub fn ancestors(
     start_from_impl: DefId,
 ) -> Result<Ancestors<'tcx>, ErrorReported> {
     let specialization_graph = tcx.specialization_graph_of(trait_def_id);
-    if specialization_graph.has_errored {
+
+    if specialization_graph.has_errored || tcx.type_of(start_from_impl).references_error() {
         Err(ErrorReported)
     } else {
         Ok(Ancestors {
diff --git a/src/test/ui/specialization/min_specialization/impl-on-nonexisting.rs b/src/test/ui/specialization/min_specialization/impl-on-nonexisting.rs
new file mode 100644
index 00000000000..77a64320d6f
--- /dev/null
+++ b/src/test/ui/specialization/min_specialization/impl-on-nonexisting.rs
@@ -0,0 +1,7 @@
+#![feature(min_specialization)]
+
+trait Trait {}
+impl Trait for NonExistent {}
+//~^ ERROR cannot find type `NonExistent` in this scope
+
+fn main() {}
diff --git a/src/test/ui/specialization/min_specialization/impl-on-nonexisting.stderr b/src/test/ui/specialization/min_specialization/impl-on-nonexisting.stderr
new file mode 100644
index 00000000000..b032ccbe53f
--- /dev/null
+++ b/src/test/ui/specialization/min_specialization/impl-on-nonexisting.stderr
@@ -0,0 +1,9 @@
+error[E0412]: cannot find type `NonExistent` in this scope
+  --> $DIR/impl-on-nonexisting.rs:4:16
+   |
+LL | impl Trait for NonExistent {}
+   |                ^^^^^^^^^^^ not found in this scope
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0412`.