hir typeck: look into nested goals

uses a `ProofTreeVisitor` to look into nested
goals when looking at the pending obligations
during hir typeck. Used by closure signature
inference, coercion, and for async functions.

10 files changed, 84 insertions, 28 deletions

diff --git a/tests/ui/closures/deduce-signature/deduce-from-opaque-type-after-norm.rs b/tests/ui/closures/deduce-signature/deduce-from-opaque-type-after-norm.rs
new file mode 100644
index 00000000000..9885d381d24
--- /dev/null
+++ b/tests/ui/closures/deduce-signature/deduce-from-opaque-type-after-norm.rs
@@ -0,0 +1,11 @@
+//@ revisions: current next
+//@ ignore-compare-mode-next-solver (explicit revisions)
+//@[next] compile-flags: -Znext-solver
+//@ check-pass
+trait Foo {
+    fn test() -> impl Fn(u32) -> u32 {
+        |x| x.count_ones()
+    }
+}
+
+fn main() {}
diff --git a/tests/ui/closures/deduce-signature/deduce-from-opaque-type.rs b/tests/ui/closures/deduce-signature/deduce-from-opaque-type.rs
new file mode 100644
index 00000000000..3185a431f0b
--- /dev/null
+++ b/tests/ui/closures/deduce-signature/deduce-from-opaque-type.rs
@@ -0,0 +1,9 @@
+//@ revisions: current next
+//@ ignore-compare-mode-next-solver (explicit revisions)
+//@[next] compile-flags: -Znext-solver
+//@ check-pass
+fn foo() -> impl FnOnce(u32) -> u32 {
+    |x| x.leading_zeros()
+}
+
+fn main() {}
diff --git a/tests/ui/closures/deduce-signature/infer-higher-ranked-signature.rs b/tests/ui/closures/deduce-signature/infer-higher-ranked-signature.rs
new file mode 100644
index 00000000000..d9ab0149087
--- /dev/null
+++ b/tests/ui/closures/deduce-signature/infer-higher-ranked-signature.rs
@@ -0,0 +1,20 @@
+//@ revisions: current next
+//@ ignore-compare-mode-next-solver (explicit revisions)
+//@[next] compile-flags: -Znext-solver
+//@ check-pass
+
+trait Foo {}
+fn needs_foo<T>(_: T)
+where
+    Wrap<T>: Foo,
+{
+}
+
+struct Wrap<T>(T);
+impl<T> Foo for Wrap<T> where T: for<'a> Fn(&'a i32) {}
+
+fn main() {
+    needs_foo(|x| {
+        x.to_string();
+    });
+}
diff --git a/tests/ui/closures/infer-signature-from-impl.rs b/tests/ui/closures/deduce-signature/infer-signature-from-impl.rs
index fa455c15ec7..20802ce37ee 100644
--- a/tests/ui/closures/infer-signature-from-impl.rs
+++ b/tests/ui/closures/deduce-signature/infer-signature-from-impl.rs
@@ -1,8 +1,7 @@
 //@ revisions: current next
 //@ ignore-compare-mode-next-solver (explicit revisions)
 //@[next] compile-flags: -Znext-solver
-//@[next] known-bug: trait-system-refactor-initiative#71
-//@[current] check-pass
+//@ check-pass
 
 trait Foo {}
 fn needs_foo<T>(_: T)
diff --git a/tests/ui/closures/deduce-signature/obligation-with-leaking-placeholders.current.stderr b/tests/ui/closures/deduce-signature/obligation-with-leaking-placeholders.current.stderr
new file mode 100644
index 00000000000..eaa0d32e75d
--- /dev/null
+++ b/tests/ui/closures/deduce-signature/obligation-with-leaking-placeholders.current.stderr
@@ -0,0 +1,15 @@
+error: implementation of `Foo` is not general enough
+  --> $DIR/obligation-with-leaking-placeholders.rs:18:5
+   |
+LL | /     needs_foo(|x| {
+LL | |
+LL | |
+LL | |         x.to_string();
+LL | |     });
+   | |______^ implementation of `Foo` is not general enough
+   |
+   = note: `Wrap<{closure@$DIR/obligation-with-leaking-placeholders.rs:18:15: 18:18}>` must implement `Foo<'0>`, for any lifetime `'0`...
+   = note: ...but it actually implements `Foo<'1>`, for some specific lifetime `'1`
+
+error: aborting due to 1 previous error
+
diff --git a/tests/ui/closures/infer-signature-from-impl.next.stderr b/tests/ui/closures/deduce-signature/obligation-with-leaking-placeholders.next.stderr
index 332917eaaff..3d667f12371 100644
--- a/tests/ui/closures/infer-signature-from-impl.next.stderr
+++ b/tests/ui/closures/deduce-signature/obligation-with-leaking-placeholders.next.stderr
@@ -1,8 +1,9 @@
 error[E0282]: type annotations needed
-  --> $DIR/infer-signature-from-impl.rs:18:16
+  --> $DIR/obligation-with-leaking-placeholders.rs:18:16
    |
 LL |     needs_foo(|x| {
    |                ^
+...
 LL |         x.to_string();
    |         - type must be known at this point
    |
diff --git a/tests/ui/closures/deduce-signature/obligation-with-leaking-placeholders.rs b/tests/ui/closures/deduce-signature/obligation-with-leaking-placeholders.rs
new file mode 100644
index 00000000000..deb888ec286
--- /dev/null
+++ b/tests/ui/closures/deduce-signature/obligation-with-leaking-placeholders.rs
@@ -0,0 +1,23 @@
+//@ revisions: current next
+//@ ignore-compare-mode-next-solver (explicit revisions)
+//@[next] compile-flags: -Znext-solver
+
+// See #124385 for more details.
+
+trait Foo<'a> {}
+fn needs_foo<T>(_: T)
+where
+    for<'a> Wrap<T>: Foo<'a>,
+{
+}
+
+struct Wrap<T>(T);
+impl<'a, T> Foo<'a> for Wrap<T> where T: Fn(&'a i32) {}
+
+fn main() {
+    needs_foo(|x| {
+        //[current]~^ implementation of `Foo` is not general enough
+        //[next]~^^ ERROR type annotations needed
+        x.to_string();
+    });
+}
diff --git a/tests/ui/closures/issue-23012-supertrait-signature-inference.rs b/tests/ui/closures/deduce-signature/supertrait-signature-inference-issue-23012.rs
index 732f687309c..16890b28acd 100644
--- a/tests/ui/closures/issue-23012-supertrait-signature-inference.rs
+++ b/tests/ui/closures/deduce-signature/supertrait-signature-inference-issue-23012.rs
@@ -1,3 +1,6 @@
+//@ revisions: current next
+//@ ignore-compare-mode-next-solver (explicit revisions)
+//@[next] compile-flags: -Znext-solver
 //@ check-pass
 // Checks that we can infer a closure signature even if the `FnOnce` bound is
 // a supertrait of the obligations we have currently registered for the Ty var.
diff --git a/tests/ui/traits/next-solver/deduce-closure-signature-after-normalization.rs b/tests/ui/traits/next-solver/deduce-closure-signature-after-normalization.rs
deleted file mode 100644
index a0fe7f0d0a5..00000000000
--- a/tests/ui/traits/next-solver/deduce-closure-signature-after-normalization.rs
+++ /dev/null
@@ -1,11 +0,0 @@
-//@ compile-flags: -Znext-solver
-// FIXME(-Znext-solver): This test is currently broken because the `deduce_closure_signature`
-// is unable to look at nested obligations.
-trait Foo {
-    fn test() -> impl Fn(u32) -> u32 {
-        |x| x.count_ones()
-        //~^ ERROR type annotations needed
-    }
-}
-
-fn main() {}
diff --git a/tests/ui/traits/next-solver/deduce-closure-signature-after-normalization.stderr b/tests/ui/traits/next-solver/deduce-closure-signature-after-normalization.stderr
deleted file mode 100644
index 3d7cd1af467..00000000000
--- a/tests/ui/traits/next-solver/deduce-closure-signature-after-normalization.stderr
+++ /dev/null
@@ -1,14 +0,0 @@
-error[E0282]: type annotations needed
-  --> $DIR/deduce-closure-signature-after-normalization.rs:6:10
-   |
-LL |         |x| x.count_ones()
-   |          ^  - type must be known at this point
-   |
-help: consider giving this closure parameter an explicit type
-   |
-LL |         |x: /* Type */| x.count_ones()
-   |           ++++++++++++
-
-error: aborting due to 1 previous error
-
-For more information about this error, try `rustc --explain E0282`.