Fix const qualification when executed after promotion

The const qualification was so far performed before the promotion and
the implementation assumed that it will never encounter a promoted.

With `const_precise_live_drops` feature, checking for live drops is
delayed until after drop elaboration, which in turn runs after
promotion. so the assumption is no longer true. When evaluating
`NeedsNonConstDrop` it is now possible to encounter promoteds.

Use type base qualification for the promoted. It is a sound
approximation in general, and in the specific case of promoteds and
`NeedsNonConstDrop` it is precise.

1 files changed, 9 insertions, 0 deletions

diff --git a/src/test/ui/consts/precise-drop-with-promoted.rs b/src/test/ui/consts/precise-drop-with-promoted.rs
new file mode 100644
index 00000000000..6f2317a5a27
--- /dev/null
+++ b/src/test/ui/consts/precise-drop-with-promoted.rs
@@ -0,0 +1,9 @@
+// Regression test for issue #89938.
+// check-pass
+// compile-flags: --crate-type=lib
+#![feature(const_precise_live_drops)]
+
+pub const fn f() {
+    let _: Option<String> = None;
+    let _: &'static Option<String> = &None;
+}