fix #4187

Author: NikolajBjorner

src/ast/rewriter/rewriter.cpp

@@ -18,6 +18,7 @@ Module Name:
 --*/
 #include "ast/rewriter/rewriter_def.h"
 #include "ast/ast_ll_pp.h"
+#include "ast/ast_pp.h"
 #include "ast/ast_smt2_pp.h"
 
 void rewriter_core::init_cache_stack() {
@@ -47,6 +48,9 @@ bool rewriter_core::rewrites_from(expr* t, proof* p) {
 }
 
 bool rewriter_core::rewrites_to(expr* t, proof* p) {
+    CTRACE("rewriter", p && !m().proofs_disabled() && to_app(m().get_fact(p))->get_arg(1) != t, 
+           tout << mk_pp(p, m()) << "\n";
+           tout << mk_pp(t, m()) << "\n";);
     return !p || m().proofs_disabled() || (to_app(m().get_fact(p))->get_arg(1) == t); 
 }
 
@@ -76,6 +80,8 @@ void rewriter_core::cache_shifted_result(expr * k, unsigned offset, expr * v) {
 void rewriter_core::cache_result(expr * k, expr * v, proof * pr) {
     m_cache->insert(k, v);
     SASSERT(m_proof_gen);
+    SASSERT(rewrites_from(k, pr));
+    SASSERT(rewrites_to(v, pr));
     m_cache_pr->insert(k, pr);
 }
 

src/ast/rewriter/th_rewriter.cpp

@@ -698,11 +698,12 @@ struct th_rewriter_cfg : public default_rewriter_cfg {
                 p1 = m().mk_pull_quant(old_q, q1);
             }
         }
-        else if (
-                 old_q->get_kind() == lambda_k &&
+        else if (old_q->get_kind() == lambda_k &&
                  is_ground(new_body)) {
             result = m_ar_rw.util().mk_const_array(old_q->get_sort(), new_body);
-            result_pr = nullptr;
+            if (m().proofs_enabled()) {
+                result_pr = m().mk_rewrite(old_q, result);
+            }
             return true;
         }
         else {