Rollup merge of #102568 - compiler-errors:lint-unsatisfied-opaques, r=oli-obk

Lint against nested opaque types that don't satisfy associated type bounds

See the test failures for examples of places where this lint would fire.

r? `@oli-obk`

12 files changed, 108 insertions, 0 deletions

diff --git a/src/test/ui/impl-trait/nested-return-type2-tait.rs b/src/test/ui/impl-trait/nested-return-type2-tait.rs
index 42613d5ccd9..089018a1cdf 100644
--- a/src/test/ui/impl-trait/nested-return-type2-tait.rs
+++ b/src/test/ui/impl-trait/nested-return-type2-tait.rs
@@ -26,6 +26,7 @@ type Sendable = impl Send;
 // var to make it uphold the `: Duh` bound on `Trait::Assoc`. The opaque
 // type does not implement `Duh`, but if its hidden type does.
 fn foo() -> impl Trait<Assoc = Sendable> {
+    //~^ WARN opaque type `impl Trait<Assoc = Sendable>` does not satisfy its associated type bounds
     || 42
 }
 
diff --git a/src/test/ui/impl-trait/nested-return-type2-tait.stderr b/src/test/ui/impl-trait/nested-return-type2-tait.stderr
new file mode 100644
index 00000000000..a8eb69cfcb7
--- /dev/null
+++ b/src/test/ui/impl-trait/nested-return-type2-tait.stderr
@@ -0,0 +1,17 @@
+warning: opaque type `impl Trait<Assoc = Sendable>` does not satisfy its associated type bounds
+  --> $DIR/nested-return-type2-tait.rs:28:24
+   |
+LL |     type Assoc: Duh;
+   |                 --- this associated type bound is unsatisfied for `Sendable`
+...
+LL | fn foo() -> impl Trait<Assoc = Sendable> {
+   |                        ^^^^^^^^^^^^^^^^
+   |
+   = note: `#[warn(opaque_hidden_inferred_bound)]` on by default
+help: add this bound
+   |
+LL | type Sendable = impl Send + Duh;
+   |                           +++++
+
+warning: 1 warning emitted
+
diff --git a/src/test/ui/impl-trait/nested-return-type2.rs b/src/test/ui/impl-trait/nested-return-type2.rs
index 39928d543e1..cc1f1f4ec44 100644
--- a/src/test/ui/impl-trait/nested-return-type2.rs
+++ b/src/test/ui/impl-trait/nested-return-type2.rs
@@ -23,6 +23,7 @@ impl<R: Duh, F: FnMut() -> R> Trait for F {
 // Lazy TAIT would error out, but we inserted a hack to make it work again,
 // keeping backwards compatibility.
 fn foo() -> impl Trait<Assoc = impl Send> {
+    //~^ WARN opaque type `impl Trait<Assoc = impl Send>` does not satisfy its associated type bounds
     || 42
 }
 
diff --git a/src/test/ui/impl-trait/nested-return-type2.stderr b/src/test/ui/impl-trait/nested-return-type2.stderr
new file mode 100644
index 00000000000..3aed05ca132
--- /dev/null
+++ b/src/test/ui/impl-trait/nested-return-type2.stderr
@@ -0,0 +1,17 @@
+warning: opaque type `impl Trait<Assoc = impl Send>` does not satisfy its associated type bounds
+  --> $DIR/nested-return-type2.rs:25:24
+   |
+LL |     type Assoc: Duh;
+   |                 --- this associated type bound is unsatisfied for `impl Send`
+...
+LL | fn foo() -> impl Trait<Assoc = impl Send> {
+   |                        ^^^^^^^^^^^^^^^^^
+   |
+   = note: `#[warn(opaque_hidden_inferred_bound)]` on by default
+help: add this bound
+   |
+LL | fn foo() -> impl Trait<Assoc = impl Send + Duh> {
+   |                                          +++++
+
+warning: 1 warning emitted
+
diff --git a/src/test/ui/impl-trait/nested-return-type3-tait.rs b/src/test/ui/impl-trait/nested-return-type3-tait.rs
index 3936f4dbbb4..3a97e35b4c4 100644
--- a/src/test/ui/impl-trait/nested-return-type3-tait.rs
+++ b/src/test/ui/impl-trait/nested-return-type3-tait.rs
@@ -17,6 +17,7 @@ impl<F: Duh> Trait for F {
 type Sendable = impl Send;
 
 fn foo() -> impl Trait<Assoc = Sendable> {
+    //~^ WARN opaque type `impl Trait<Assoc = Sendable>` does not satisfy its associated type bounds
     42
 }
 
diff --git a/src/test/ui/impl-trait/nested-return-type3-tait.stderr b/src/test/ui/impl-trait/nested-return-type3-tait.stderr
new file mode 100644
index 00000000000..5f58c8dca4a
--- /dev/null
+++ b/src/test/ui/impl-trait/nested-return-type3-tait.stderr
@@ -0,0 +1,17 @@
+warning: opaque type `impl Trait<Assoc = Sendable>` does not satisfy its associated type bounds
+  --> $DIR/nested-return-type3-tait.rs:19:24
+   |
+LL |     type Assoc: Duh;
+   |                 --- this associated type bound is unsatisfied for `Sendable`
+...
+LL | fn foo() -> impl Trait<Assoc = Sendable> {
+   |                        ^^^^^^^^^^^^^^^^
+   |
+   = note: `#[warn(opaque_hidden_inferred_bound)]` on by default
+help: add this bound
+   |
+LL | type Sendable = impl Send + Duh;
+   |                           +++++
+
+warning: 1 warning emitted
+
diff --git a/src/test/ui/impl-trait/nested-return-type3-tait2.rs b/src/test/ui/impl-trait/nested-return-type3-tait2.rs
index 56778ed90dc..5b6f78a9896 100644
--- a/src/test/ui/impl-trait/nested-return-type3-tait2.rs
+++ b/src/test/ui/impl-trait/nested-return-type3-tait2.rs
@@ -16,6 +16,7 @@ impl<F: Duh> Trait for F {
 
 type Sendable = impl Send;
 type Traitable = impl Trait<Assoc = Sendable>;
+//~^ WARN opaque type `Traitable` does not satisfy its associated type bounds
 
 fn foo() -> Traitable {
     42
diff --git a/src/test/ui/impl-trait/nested-return-type3-tait2.stderr b/src/test/ui/impl-trait/nested-return-type3-tait2.stderr
new file mode 100644
index 00000000000..c07f6ead750
--- /dev/null
+++ b/src/test/ui/impl-trait/nested-return-type3-tait2.stderr
@@ -0,0 +1,17 @@
+warning: opaque type `Traitable` does not satisfy its associated type bounds
+  --> $DIR/nested-return-type3-tait2.rs:18:29
+   |
+LL |     type Assoc: Duh;
+   |                 --- this associated type bound is unsatisfied for `Sendable`
+...
+LL | type Traitable = impl Trait<Assoc = Sendable>;
+   |                             ^^^^^^^^^^^^^^^^
+   |
+   = note: `#[warn(opaque_hidden_inferred_bound)]` on by default
+help: add this bound
+   |
+LL | type Sendable = impl Send + Duh;
+   |                           +++++
+
+warning: 1 warning emitted
+
diff --git a/src/test/ui/impl-trait/nested-return-type3-tait3.rs b/src/test/ui/impl-trait/nested-return-type3-tait3.rs
index 04c6c92b1a3..394d8f58110 100644
--- a/src/test/ui/impl-trait/nested-return-type3-tait3.rs
+++ b/src/test/ui/impl-trait/nested-return-type3-tait3.rs
@@ -15,6 +15,7 @@ impl<F: Duh> Trait for F {
 }
 
 type Traitable = impl Trait<Assoc = impl Send>;
+//~^ WARN opaque type `Traitable` does not satisfy its associated type bounds
 
 fn foo() -> Traitable {
     42
diff --git a/src/test/ui/impl-trait/nested-return-type3-tait3.stderr b/src/test/ui/impl-trait/nested-return-type3-tait3.stderr
new file mode 100644
index 00000000000..d98ad89222f
--- /dev/null
+++ b/src/test/ui/impl-trait/nested-return-type3-tait3.stderr
@@ -0,0 +1,17 @@
+warning: opaque type `Traitable` does not satisfy its associated type bounds
+  --> $DIR/nested-return-type3-tait3.rs:17:29
+   |
+LL |     type Assoc: Duh;
+   |                 --- this associated type bound is unsatisfied for `impl Send`
+...
+LL | type Traitable = impl Trait<Assoc = impl Send>;
+   |                             ^^^^^^^^^^^^^^^^^
+   |
+   = note: `#[warn(opaque_hidden_inferred_bound)]` on by default
+help: add this bound
+   |
+LL | type Traitable = impl Trait<Assoc = impl Send + Duh>;
+   |                                               +++++
+
+warning: 1 warning emitted
+
diff --git a/src/test/ui/impl-trait/nested-return-type3.rs b/src/test/ui/impl-trait/nested-return-type3.rs
index 74b4dae22eb..5a764fc4c28 100644
--- a/src/test/ui/impl-trait/nested-return-type3.rs
+++ b/src/test/ui/impl-trait/nested-return-type3.rs
@@ -13,6 +13,7 @@ impl<F: Duh> Trait for F {
 }
 
 fn foo() -> impl Trait<Assoc = impl Send> {
+    //~^ WARN opaque type `impl Trait<Assoc = impl Send>` does not satisfy its associated type bounds
     42
 }
 
diff --git a/src/test/ui/impl-trait/nested-return-type3.stderr b/src/test/ui/impl-trait/nested-return-type3.stderr
new file mode 100644
index 00000000000..632de71aa4c
--- /dev/null
+++ b/src/test/ui/impl-trait/nested-return-type3.stderr
@@ -0,0 +1,17 @@
+warning: opaque type `impl Trait<Assoc = impl Send>` does not satisfy its associated type bounds
+  --> $DIR/nested-return-type3.rs:15:24
+   |
+LL |     type Assoc: Duh;
+   |                 --- this associated type bound is unsatisfied for `impl Send`
+...
+LL | fn foo() -> impl Trait<Assoc = impl Send> {
+   |                        ^^^^^^^^^^^^^^^^^
+   |
+   = note: `#[warn(opaque_hidden_inferred_bound)]` on by default
+help: add this bound
+   |
+LL | fn foo() -> impl Trait<Assoc = impl Send + Duh> {
+   |                                          +++++
+
+warning: 1 warning emitted
+