Extend `QueryStability` to handle `IntoIterator` implementations

Fix adjacent code

Fix duplicate warning; merge test into `tests/ui-fulldeps/internal-lints`

Use `rustc_middle::ty::FnSig::inputs`

Address two review comments

- https://github.com/rust-lang/rust/pull/139345#discussion_r2109006991
- https://github.com/rust-lang/rust/pull/139345#discussion_r2109058588

Use `Instance::try_resolve`

Import `rustc_middle::ty::Ty` as `Ty` rather than `MiddleTy`

Simplify predicate handling

Add more `#[allow(rustc::potential_query_instability)]` following rebase

Remove two `#[allow(rustc::potential_query_instability)]` following rebase

Address review comment

Update compiler/rustc_lint/src/internal.rs

Co-authored-by: lcnr <rust@lcnr.de>

2 files changed, 29 insertions, 1 deletions

diff --git a/tests/ui-fulldeps/internal-lints/query_stability.rs b/tests/ui-fulldeps/internal-lints/query_stability.rs
index 7b897fabd2d..9dc65250064 100644
--- a/tests/ui-fulldeps/internal-lints/query_stability.rs
+++ b/tests/ui-fulldeps/internal-lints/query_stability.rs
@@ -34,4 +34,16 @@ fn main() {
         //~^ ERROR using `values_mut` can result in unstable query results
         *val = *val + 10;
     }
+
+    FxHashMap::<u32, i32>::default().extend(x);
+    //~^ ERROR using `into_iter` can result in unstable query results
+}
+
+fn hide_into_iter<T>(x: impl IntoIterator<Item = T>) -> impl Iterator<Item = T> {
+    x.into_iter()
+}
+
+fn take(map: std::collections::HashMap<i32, i32>) {
+    _ = hide_into_iter(map);
+    //~^ ERROR using `into_iter` can result in unstable query results
 }
diff --git a/tests/ui-fulldeps/internal-lints/query_stability.stderr b/tests/ui-fulldeps/internal-lints/query_stability.stderr
index 43b156dc20a..a95ffd25a47 100644
--- a/tests/ui-fulldeps/internal-lints/query_stability.stderr
+++ b/tests/ui-fulldeps/internal-lints/query_stability.stderr
@@ -59,5 +59,21 @@ LL |     for val in x.values_mut() {
    |
    = note: if you believe this case to be fine, allow this lint and add a comment explaining your rationale
 
-error: aborting due to 7 previous errors
+error: using `into_iter` can result in unstable query results
+  --> $DIR/query_stability.rs:38:38
+   |
+LL |     FxHashMap::<u32, i32>::default().extend(x);
+   |                                      ^^^^^^^^^
+   |
+   = note: if you believe this case to be fine, allow this lint and add a comment explaining your rationale
+
+error: using `into_iter` can result in unstable query results
+  --> $DIR/query_stability.rs:47:9
+   |
+LL |     _ = hide_into_iter(map);
+   |         ^^^^^^^^^^^^^^^^^^^
+   |
+   = note: if you believe this case to be fine, allow this lint and add a comment explaining your rationale
+
+error: aborting due to 9 previous errors