address review: add explanation for tests

Author: LorrensP-2158466

tests/ui/regions/closure-prop-issue-104477-case1.rs

@@ -1,5 +1,8 @@
 //@ check-pass
-
+// This checks that the compiler does not require that 'a: 'b. '_ has 'a and 'b as non-local
+// upper bounds, but the compiler should not propagate 'a: 'b OR 'b: 'a when checking
+// the closures. If it did, this would fail to compile, eventhough it's a valid program.
+// PR #148329 explains this in detail.
 
 struct MyTy<'x, 'a, 'b>(std::cell::Cell<(&'x &'a u8, &'x &'b u8)>);
 fn wf<T>(_: T) {}

tests/ui/regions/closure-prop-issue-148289.rs

@@ -1,4 +1,8 @@
 //@ check-pass
+// This test checks that the compiler does not propagate 'd: 'c when propagating region errors
+// for the closure argument. If it did, this would fail to compile, eventhough it's a valid program.
+// It should only propagate 'd: 'c.
+// PR #148329 explains this in detail.
 
 #[derive(Clone, Copy)]
 struct Inv<'a>(*mut &'a ());