Rollup merge of #63582 - JohnTitor:fix-ice-63226, r=oli-obk

Fix ICE #63226

Fixes #63226

r? @oli-obk

src/test/ui/consts/auxiliary/issue-63226.rs

@@ -0,0 +1,14 @@
+pub struct VTable{
+    state:extern fn(),
+}
+
+impl VTable{
+    pub const fn vtable()->&'static VTable{
+        Self::VTABLE
+    }
+
+    const VTABLE: &'static VTable =
+        &VTable{state};
+}
+
+extern fn state() {}

src/test/ui/consts/issue-63226.rs

@@ -0,0 +1,12 @@
+// aux-build:issue-63226.rs
+// compile-flags:--extern issue_63226
+// edition:2018
+// build-pass
+// A regression test for issue #63226.
+// Checks if `const fn` is marked as reachable.
+
+use issue_63226::VTable;
+
+static ICE_ICE:&'static VTable=VTable::vtable();
+
+fn main() {}