From f79fa636bfc99bf24d8df5124d26fbbab04b5f8c Mon Sep 17 00:00:00 2001
From: Adwin White <adwinw01@gmail.com>
Date: Fri, 24 Jul 2026 16:08:58 +0800
Subject: [PATCH] add missing resolving vars

---
 .../query/type_op/implied_outlives_bounds.rs  |  1 +
 ..._outlives_bounds_not_resolving_vars_ice.rs | 19 ++++++++++++
 ...lives_bounds_not_resolving_vars_ice.stderr | 29 +++++++++++++++++++
 3 files changed, 49 insertions(+)
 create mode 100644 tests/ui/traits/next-solver/implied_outlives_bounds_not_resolving_vars_ice.rs
 create mode 100644 tests/ui/traits/next-solver/implied_outlives_bounds_not_resolving_vars_ice.stderr

diff --git a/compiler/rustc_trait_selection/src/traits/query/type_op/implied_outlives_bounds.rs b/compiler/rustc_trait_selection/src/traits/query/type_op/implied_outlives_bounds.rs
index a98f8b9a9af88..e55f87c6076e6 100644
--- a/compiler/rustc_trait_selection/src/traits/query/type_op/implied_outlives_bounds.rs
+++ b/compiler/rustc_trait_selection/src/traits/query/type_op/implied_outlives_bounds.rs
@@ -95,6 +95,7 @@ pub fn compute_implied_outlives_bounds_inner<'tcx>(
             continue;
         }
 
+        let arg = ocx.infcx.resolve_vars_if_possible(arg);
         // From the full set of obligations, just filter down to the region relationships.
         for obligation in
             wf::unnormalized_obligations(ocx.infcx, param_env, arg, DUMMY_SP, CRATE_DEF_ID)
diff --git a/tests/ui/traits/next-solver/implied_outlives_bounds_not_resolving_vars_ice.rs b/tests/ui/traits/next-solver/implied_outlives_bounds_not_resolving_vars_ice.rs
new file mode 100644
index 0000000000000..a1e60c38fbbc8
--- /dev/null
+++ b/tests/ui/traits/next-solver/implied_outlives_bounds_not_resolving_vars_ice.rs
@@ -0,0 +1,19 @@
+//@ compile-flags: -Znext-solver
+
+// Regression test for https://github.com/rust-lang/rust-clippy/issues/17439
+
+#![feature(inherent_associated_types)]
+
+struct Foo<T>(T);
+
+impl<'a> Foo<fn(&'a ())> {
+    type Assoc = &'a ();
+}
+
+fn bar(_: fn(Foo<for<'b> fn(Foo<fn(&'b ())>::Assoc)>::Assoc)) {}
+//~^ ERROR: higher-ranked subtype error
+//~| ERROR: higher-ranked subtype error
+//~| ERROR: lifetime bound not satisfied [E0478]
+//~| ERROR: lifetime bound not satisfied [E0478]
+
+fn main() {}
diff --git a/tests/ui/traits/next-solver/implied_outlives_bounds_not_resolving_vars_ice.stderr b/tests/ui/traits/next-solver/implied_outlives_bounds_not_resolving_vars_ice.stderr
new file mode 100644
index 0000000000000..6a79474f60915
--- /dev/null
+++ b/tests/ui/traits/next-solver/implied_outlives_bounds_not_resolving_vars_ice.stderr
@@ -0,0 +1,29 @@
+error[E0478]: lifetime bound not satisfied
+  --> $DIR/implied_outlives_bounds_not_resolving_vars_ice.rs:13:11
+   |
+LL | fn bar(_: fn(Foo<for<'b> fn(Foo<fn(&'b ())>::Assoc)>::Assoc)) {}
+   |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error[E0478]: lifetime bound not satisfied
+  --> $DIR/implied_outlives_bounds_not_resolving_vars_ice.rs:13:11
+   |
+LL | fn bar(_: fn(Foo<for<'b> fn(Foo<fn(&'b ())>::Assoc)>::Assoc)) {}
+   |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+
+error: higher-ranked subtype error
+  --> $DIR/implied_outlives_bounds_not_resolving_vars_ice.rs:13:1
+   |
+LL | fn bar(_: fn(Foo<for<'b> fn(Foo<fn(&'b ())>::Assoc)>::Assoc)) {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: higher-ranked subtype error
+  --> $DIR/implied_outlives_bounds_not_resolving_vars_ice.rs:13:8
+   |
+LL | fn bar(_: fn(Foo<for<'b> fn(Foo<fn(&'b ())>::Assoc)>::Assoc)) {}
+   |        ^
+
+error: aborting due to 4 previous errors
+
+For more information about this error, try `rustc --explain E0478`.