Avoid cycles from projection bounds

Only check the own predicates of associated types when confirming
projection candidates.
Also consider implied bounds when comparing trait and impl methods.

8 files changed, 61 insertions, 61 deletions

diff --git a/src/test/ui/associated-types/wf-cycle-2.rs b/src/test/ui/associated-types/wf-cycle-2.rs
new file mode 100644
index 00000000000..d7467ac2237
--- /dev/null
+++ b/src/test/ui/associated-types/wf-cycle-2.rs
@@ -0,0 +1,18 @@
+// check-pass
+
+trait IntoIt {
+    type Item;
+}
+
+impl<I> IntoIt for I {
+    type Item = ();
+}
+
+trait BaseGraph
+where
+    <Self::VertexIter as IntoIt>::Item: Sized,
+{
+    type VertexIter: IntoIt;
+}
+
+fn main() {}
diff --git a/src/test/ui/associated-types/wf-cycle.rs b/src/test/ui/associated-types/wf-cycle.rs
new file mode 100644
index 00000000000..cf6508551a5
--- /dev/null
+++ b/src/test/ui/associated-types/wf-cycle.rs
@@ -0,0 +1,13 @@
+// check-pass
+
+trait A {
+    type U: Copy;
+}
+
+trait B where
+    <Self::V as A>::U: Copy,
+{
+    type V: A;
+}
+
+fn main() {}
diff --git a/src/test/ui/regions/regions-trait-1.rs b/src/test/ui/regions/regions-trait-1.rs
index 0da8ac53695..b6dab1c32e8 100644
--- a/src/test/ui/regions/regions-trait-1.rs
+++ b/src/test/ui/regions/regions-trait-1.rs
@@ -1,30 +1,33 @@
-#![feature(box_syntax)]
+// check-pass
 
-struct Ctxt { v: usize }
+struct Ctxt {
+    v: usize,
+}
 
 trait GetCtxt {
     // Here the `&` is bound in the method definition:
     fn get_ctxt(&self) -> &Ctxt;
 }
 
-struct HasCtxt<'a> { c: &'a Ctxt }
+struct HasCtxt<'a> {
+    c: &'a Ctxt,
+}
 
 impl<'a> GetCtxt for HasCtxt<'a> {
-
-    // Here an error occurs because we used `&self` but
-    // the definition used `&`:
-    fn get_ctxt(&self) -> &'a Ctxt { //~ ERROR method not compatible with trait
+    // Ok: Have implied bound of WF(&'b HasCtxt<'a>)
+    // so know 'a: 'b
+    // so know &'a Ctxt <: &'b Ctxt
+    fn get_ctxt<'b>(&'b self) -> &'a Ctxt {
         self.c
     }
-
 }
 
-fn get_v(gc: Box<dyn GetCtxt>) -> usize {
+fn get_v(gc: Box<dyn GetCtxt + '_>) -> usize {
     gc.get_ctxt().v
 }
 
 fn main() {
     let ctxt = Ctxt { v: 22 };
     let hc = HasCtxt { c: &ctxt };
-    assert_eq!(get_v(box hc as Box<dyn GetCtxt>), 22);
+    assert_eq!(get_v(Box::new(hc) as Box<dyn GetCtxt>), 22);
 }
diff --git a/src/test/ui/regions/regions-trait-1.stderr b/src/test/ui/regions/regions-trait-1.stderr
deleted file mode 100644
index 92d96a722d4..00000000000
--- a/src/test/ui/regions/regions-trait-1.stderr
+++ /dev/null
@@ -1,22 +0,0 @@
-error[E0308]: method not compatible with trait
-  --> $DIR/regions-trait-1.rs:16:5
-   |
-LL |     fn get_ctxt(&self) -> &'a Ctxt {
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ lifetime mismatch
-   |
-   = note: expected fn pointer `fn(&HasCtxt<'a>) -> &Ctxt`
-              found fn pointer `fn(&HasCtxt<'a>) -> &'a Ctxt`
-note: the lifetime `'a` as defined on the impl at 12:6...
-  --> $DIR/regions-trait-1.rs:12:6
-   |
-LL | impl<'a> GetCtxt for HasCtxt<'a> {
-   |      ^^
-note: ...does not necessarily outlive the anonymous lifetime #1 defined on the method body at 16:5
-  --> $DIR/regions-trait-1.rs:16:5
-   |
-LL |     fn get_ctxt(&self) -> &'a Ctxt {
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-error: aborting due to previous error
-
-For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/specialization/issue-38091-2.rs b/src/test/ui/specialization/issue-38091-2.rs
index da7f6737733..9ed0b240d0a 100644
--- a/src/test/ui/specialization/issue-38091-2.rs
+++ b/src/test/ui/specialization/issue-38091-2.rs
@@ -1,3 +1,6 @@
+// build-fail
+//~^ ERROR overflow evaluating the requirement `i32: Check`
+
 #![feature(specialization)]
 //~^ WARN the feature `specialization` is incomplete
 
@@ -5,7 +8,10 @@ trait Iterate<'a> {
     type Ty: Valid;
     fn iterate(self);
 }
-impl<'a, T> Iterate<'a> for T where T: Check {
+impl<'a, T> Iterate<'a> for T
+where
+    T: Check,
+{
     default type Ty = ();
     default fn iterate(self) {}
 }
@@ -19,5 +25,4 @@ impl Valid for () {}
 
 fn main() {
     Iterate::iterate(0);
-    //~^ ERROR overflow evaluating the requirement `{integer}: Check`
 }
diff --git a/src/test/ui/specialization/issue-38091-2.stderr b/src/test/ui/specialization/issue-38091-2.stderr
index e776ff0fafb..a314c26ad14 100644
--- a/src/test/ui/specialization/issue-38091-2.stderr
+++ b/src/test/ui/specialization/issue-38091-2.stderr
@@ -1,5 +1,5 @@
 warning: the feature `specialization` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/issue-38091-2.rs:1:12
+  --> $DIR/issue-38091-2.rs:4:12
    |
 LL | #![feature(specialization)]
    |            ^^^^^^^^^^^^^^
@@ -7,16 +7,9 @@ LL | #![feature(specialization)]
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
 
-error[E0275]: overflow evaluating the requirement `{integer}: Check`
-  --> $DIR/issue-38091-2.rs:21:5
+error[E0275]: overflow evaluating the requirement `i32: Check`
    |
-LL |     fn iterate(self);
-   |     ----------------- required by `Iterate::iterate`
-...
-LL |     Iterate::iterate(0);
-   |     ^^^^^^^^^^^^^^^^
-   |
-   = note: required because of the requirements on the impl of `Iterate<'_>` for `{integer}`
+   = note: required because of the requirements on the impl of `Iterate` for `i32`
 
 error: aborting due to previous error; 1 warning emitted
 
diff --git a/src/test/ui/specialization/issue-38091.rs b/src/test/ui/specialization/issue-38091.rs
index cc0eeb53687..5b398368a67 100644
--- a/src/test/ui/specialization/issue-38091.rs
+++ b/src/test/ui/specialization/issue-38091.rs
@@ -5,7 +5,10 @@ trait Iterate<'a> {
     type Ty: Valid;
     fn iterate(self);
 }
-impl<'a, T> Iterate<'a> for T where T: Check {
+impl<'a, T> Iterate<'a> for T
+where
+    T: Check,
+{
     default type Ty = ();
     //~^ ERROR the trait bound `(): Valid` is not satisfied
     default fn iterate(self) {}
@@ -18,5 +21,4 @@ trait Valid {}
 
 fn main() {
     Iterate::iterate(0);
-    //~^ ERROR overflow evaluating the requirement `{integer}: Check`
 }
diff --git a/src/test/ui/specialization/issue-38091.stderr b/src/test/ui/specialization/issue-38091.stderr
index beec702b89e..6be0f26849f 100644
--- a/src/test/ui/specialization/issue-38091.stderr
+++ b/src/test/ui/specialization/issue-38091.stderr
@@ -8,7 +8,7 @@ LL | #![feature(specialization)]
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
 
 error[E0277]: the trait bound `(): Valid` is not satisfied
-  --> $DIR/issue-38091.rs:9:5
+  --> $DIR/issue-38091.rs:12:5
    |
 LL |     type Ty: Valid;
    |              ----- required by this bound in `Iterate::Ty`
@@ -16,18 +16,6 @@ LL |     type Ty: Valid;
 LL |     default type Ty = ();
    |     ^^^^^^^^^^^^^^^^^^^^^ the trait `Valid` is not implemented for `()`
 
-error[E0275]: overflow evaluating the requirement `{integer}: Check`
-  --> $DIR/issue-38091.rs:20:5
-   |
-LL |     fn iterate(self);
-   |     ----------------- required by `Iterate::iterate`
-...
-LL |     Iterate::iterate(0);
-   |     ^^^^^^^^^^^^^^^^
-   |
-   = note: required because of the requirements on the impl of `Iterate<'_>` for `{integer}`
-
-error: aborting due to 2 previous errors; 1 warning emitted
+error: aborting due to previous error; 1 warning emitted
 
-Some errors have detailed explanations: E0275, E0277.
-For more information about an error, try `rustc --explain E0275`.
+For more information about this error, try `rustc --explain E0277`.