Foo.is_eq would return false if the type was a typedef and had an overload, but the underlying type was not comparable. Version 0.7.8.

test/test_suite/distinct/distinct_is_eq.c3

@@ -0,0 +1,12 @@
+module test;
+import std;
+struct Boo { int a; }
+typedef Foo = Boo;
+
+fn bool Foo.eq(Foo a, Foo b) @operator(==) => false;
+
+fn int main()
+{
+	$assert Foo.is_eq;
+	return 0;
+}