Add test for issue-64662

Author: JohnTitor

src/test/ui/consts/issue-64662.rs

@@ -0,0 +1,10 @@
+enum Foo {
+    A = foo(), //~ ERROR: type annotations needed
+    B = foo(), //~ ERROR: type annotations needed
+}
+
+const fn foo<T>() -> isize {
+    0
+}
+
+fn main() {}

src/test/ui/consts/issue-64662.stderr

@@ -0,0 +1,15 @@
+error[E0282]: type annotations needed
+  --> $DIR/issue-64662.rs:2:9
+   |
+LL |     A = foo(),
+   |         ^^^ cannot infer type for `T`
+
+error[E0282]: type annotations needed
+  --> $DIR/issue-64662.rs:3:9
+   |
+LL |     B = foo(),
+   |         ^^^ cannot infer type for `T`
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0282`.