The example tests/lua/simp1.lua demonstrates the issue.
The higher-order matcher matches closed terms that are definitionally equal.
So, given a definition
definition a := 1
it will match 'a' with '1' since they are definitionally equal.
Then, if we have a theorem
theorem a_eq_1 : a = 1
as a rewrite rule, it was triggering the following infinite loop when simplifying the expression "a"
a --> 1 --> 1 --> 1 ...
The first simplification is expected. The other ones are not.
The problem is that "1" is definitionally equal to "a", and they match.
The rewrite_rule_set manager accepts the rule a --> 1 since the left-hand-side does not occur in the right-hand-side.
To avoid this loop, we test if the new expression is not equal to the previous one.
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
