Add regression test for ICE with TransmuteFrom and min_generic_const_args

Add a check-pass test that exercises TransmuteFrom with
min_generic_const_args, which previously caused an ICE
(expected ConstKind::Value).

Author: jeanibarz

tests/ui/transmutability/transmute-from-const-args-ice-150457.rs

@@ -0,0 +1,31 @@
+//! Ensure `TransmuteFrom` with `min_generic_const_args` doesn't ICE
+//! during well-formedness checking.
+//!
+//! Regression test for <https://github.com/rust-lang/rust/issues/150457>.
+
+//@ check-pass (ICE was in wfcheck, not codegen)
+
+#![feature(transmutability)]
+#![feature(min_generic_const_args)]
+
+use std::mem::{Assume, TransmuteFrom};
+
+struct W<'a>(&'a ());
+
+fn test<'a>()
+where
+    W<'a>: TransmuteFrom<
+        (),
+        {
+            Assume {
+                alignment: const { true },
+                lifetimes: const { true },
+                safety: const { true },
+                validity: true,
+            }
+        },
+    >,
+{
+}
+
+fn main() {}