Guard against non-monomorphized type_id intrinsic call

2 files changed, 40 insertions, 0 deletions

diff --git a/src/test/ui/consts/issue-73976.rs b/src/test/ui/consts/issue-73976.rs
new file mode 100644
index 00000000000..ef141791c2c
--- /dev/null
+++ b/src/test/ui/consts/issue-73976.rs
@@ -0,0 +1,26 @@
+// This test is from #73976. We previously did not check if a type is monomorphized
+// before calculating its type id, which leads to the bizzare behaviour below that
+// TypeId of a generic type does not match itself.
+//
+// This test case should either run-pass or be rejected at compile time.
+// Currently we just disallow this usage and require pattern is monomorphic.
+
+#![feature(const_type_id)]
+
+use std::any::TypeId;
+
+pub struct GetTypeId<T>(T);
+
+impl<T: 'static> GetTypeId<T> {
+    pub const VALUE: TypeId = TypeId::of::<T>();
+}
+
+const fn check_type_id<T: 'static>() -> bool {
+    matches!(GetTypeId::<T>::VALUE, GetTypeId::<T>::VALUE)
+    //~^ ERROR could not evaluate constant pattern
+    //~| ERROR could not evaluate constant pattern
+}
+
+fn main() {
+    assert!(check_type_id::<usize>());
+}
diff --git a/src/test/ui/consts/issue-73976.stderr b/src/test/ui/consts/issue-73976.stderr
new file mode 100644
index 00000000000..dbb7690b849
--- /dev/null
+++ b/src/test/ui/consts/issue-73976.stderr
@@ -0,0 +1,14 @@
+error: could not evaluate constant pattern
+  --> $DIR/issue-73976.rs:19:37
+   |
+LL |     matches!(GetTypeId::<T>::VALUE, GetTypeId::<T>::VALUE)
+   |                                     ^^^^^^^^^^^^^^^^^^^^^
+
+error: could not evaluate constant pattern
+  --> $DIR/issue-73976.rs:19:37
+   |
+LL |     matches!(GetTypeId::<T>::VALUE, GetTypeId::<T>::VALUE)
+   |                                     ^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 2 previous errors
+