From 6143a2c319119c839590453c892ea5eeca9d4465 Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Wed, 10 Apr 2024 15:28:54 -0400
Subject: [PATCH] Check alias args for WF even if they have escaping bound vars

---
 .../rustc_trait_selection/src/traits/wf.rs    | 30 ++-----------------
 tests/ui/inference/issue-80409.compat.stderr  | 19 ++++++++++++
 .../ui/inference/issue-80409.no-compat.stderr | 25 +++++++++-------
 tests/ui/inference/issue-80409.rs             | 12 +-------
 4 files changed, 37 insertions(+), 49 deletions(-)
 create mode 100644 tests/ui/inference/issue-80409.compat.stderr

diff --git a/compiler/rustc_trait_selection/src/traits/wf.rs b/compiler/rustc_trait_selection/src/traits/wf.rs
index 5553490542b75..ee67b62155384 100644
--- a/compiler/rustc_trait_selection/src/traits/wf.rs
+++ b/compiler/rustc_trait_selection/src/traits/wf.rs
@@ -463,7 +463,7 @@ impl<'a, 'tcx> WfPredicates<'a, 'tcx> {
         let obligations = self.nominal_obligations(data.def_id, data.args);
         self.out.extend(obligations);
 
-        self.compute_projection_args(data.args);
+        data.args.visit_with(self);
     }
 
     /// Pushes the obligations required for an inherent alias to be WF
@@ -493,33 +493,7 @@ impl<'a, 'tcx> WfPredicates<'a, 'tcx> {
             self.out.extend(obligations);
         }
 
-        self.compute_projection_args(data.args);
-    }
-
-    fn compute_projection_args(&mut self, args: GenericArgsRef<'tcx>) {
-        let tcx = self.tcx();
-        let cause = self.cause(traits::WellFormed(None));
-        let param_env = self.param_env;
-        let depth = self.recursion_depth;
-
-        self.out.extend(
-            args.iter()
-                .filter(|arg| {
-                    matches!(arg.unpack(), GenericArgKind::Type(..) | GenericArgKind::Const(..))
-                })
-                .filter(|arg| !arg.has_escaping_bound_vars())
-                .map(|arg| {
-                    traits::Obligation::with_depth(
-                        tcx,
-                        cause.clone(),
-                        depth,
-                        param_env,
-                        ty::Binder::dummy(ty::PredicateKind::Clause(ty::ClauseKind::WellFormed(
-                            arg,
-                        ))),
-                    )
-                }),
-        );
+        data.args.visit_with(self);
     }
 
     fn require_sized(&mut self, subty: Ty<'tcx>, cause: traits::ObligationCauseCode<'tcx>) {
diff --git a/tests/ui/inference/issue-80409.compat.stderr b/tests/ui/inference/issue-80409.compat.stderr
new file mode 100644
index 0000000000000..fbc41f951d2fb
--- /dev/null
+++ b/tests/ui/inference/issue-80409.compat.stderr
@@ -0,0 +1,19 @@
+error[E0277]: the trait bound `TFsm: Fsm` is not satisfied
+  --> $DIR/issue-80409.rs:25:26
+   |
+LL |     fn on_entry<TAction: Fn(&mut StateContext<'_, TFsm>)>(&self, _action: TAction) {}
+   |                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Fsm` is not implemented for `TFsm`
+   |
+note: required by a bound in `StateContext`
+  --> $DIR/issue-80409.rs:33:31
+   |
+LL | struct StateContext<'a, TFsm: Fsm> {
+   |                               ^^^ required by this bound in `StateContext`
+help: consider restricting type parameter `TFsm`
+   |
+LL | impl<TFsm: Fsm> FsmStateBuilder<TFsm> {
+   |          +++++
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/tests/ui/inference/issue-80409.no-compat.stderr b/tests/ui/inference/issue-80409.no-compat.stderr
index c772225be7549..fbc41f951d2fb 100644
--- a/tests/ui/inference/issue-80409.no-compat.stderr
+++ b/tests/ui/inference/issue-80409.no-compat.stderr
@@ -1,14 +1,19 @@
-error: internal compiler error: error performing operation: fully_perform
-  --> $DIR/issue-80409.rs:49:30
+error[E0277]: the trait bound `TFsm: Fsm` is not satisfied
+  --> $DIR/issue-80409.rs:25:26
    |
-LL |     builder.state().on_entry(|_| {});
-   |                              ^^^
+LL |     fn on_entry<TAction: Fn(&mut StateContext<'_, TFsm>)>(&self, _action: TAction) {}
+   |                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Fsm` is not implemented for `TFsm`
    |
-note: 
-  --> $DIR/issue-80409.rs:49:30
+note: required by a bound in `StateContext`
+  --> $DIR/issue-80409.rs:33:31
    |
-LL |     builder.state().on_entry(|_| {});
-   |                              ^^^
+LL | struct StateContext<'a, TFsm: Fsm> {
+   |                               ^^^ required by this bound in `StateContext`
+help: consider restricting type parameter `TFsm`
+   |
+LL | impl<TFsm: Fsm> FsmStateBuilder<TFsm> {
+   |          +++++
+
+error: aborting due to 1 previous error
 
-query stack during panic:
-end of query stack
+For more information about this error, try `rustc --explain E0277`.
diff --git a/tests/ui/inference/issue-80409.rs b/tests/ui/inference/issue-80409.rs
index dfb84563e6d80..dbada82ca7763 100644
--- a/tests/ui/inference/issue-80409.rs
+++ b/tests/ui/inference/issue-80409.rs
@@ -1,18 +1,7 @@
 // This should not pass, because `usize: Fsm` does not hold. However, it currently ICEs.
 
-// ignore-tidy-linelength
-
 //@ revisions: compat no-compat
-//@[compat] check-pass
 //@[no-compat] compile-flags: -Zno-implied-bounds-compat
-//@[no-compat] check-fail
-//@[no-compat] known-bug: #80409
-//@[no-compat] failure-status: 101
-//@[no-compat] normalize-stderr-test "delayed at.*" -> ""
-//@[no-compat] normalize-stderr-test "note: .*\n\n" -> ""
-//@[no-compat] normalize-stderr-test "thread 'rustc' panicked.*\n" -> ""
-//@[no-compat] normalize-stderr-test "(error: internal compiler error: [^:]+):\d+:\d+: " -> "$1:LL:CC: "
-//@[no-compat] rustc-env:RUST_BACKTRACE=0
 
 #![allow(unreachable_code, unused)]
 
@@ -34,6 +23,7 @@ struct FsmStateBuilder<TFsm> {
 
 impl<TFsm> FsmStateBuilder<TFsm> {
     fn on_entry<TAction: Fn(&mut StateContext<'_, TFsm>)>(&self, _action: TAction) {}
+    //~^ ERROR the trait bound `TFsm: Fsm` is not satisfied
 }
 
 trait Fsm {