fail gracefully on interpolation errors

src/interp/iz3interp.cpp

@@ -271,7 +271,18 @@ public:
 
         // translate into an interpolatable proof
         profiling::timer_start("Proof translation");
-        tr->translate(proof,pf);
+        try {
+            tr->translate(proof,pf);
+        }
+        catch (const char *msg) {
+            throw interpolation_failure(msg);
+        }
+        catch (const iz3translation::unsupported &) {
+            throw interpolation_error();
+        }
+        catch (const iz3proof::proof_error &) {
+            throw interpolation_error();
+        }
         profiling::timer_stop("Proof translation");
     
         // translate the proof into interpolants
@@ -309,7 +320,18 @@ public:
       
             // translate into an interpolatable proof
             profiling::timer_start("Proof translation");
-            tr->translate(proof,pf);
+            try {
+                tr->translate(proof,pf);
+            }
+            catch (const char *msg) {
+                throw interpolation_failure(msg);
+            }
+            catch (const iz3translation::unsupported &) {
+                throw interpolation_error();
+            }
+            catch (const iz3proof::proof_error &) {
+                throw interpolation_error();
+            }
             profiling::timer_stop("Proof translation");
       
             // translate the proof into interpolants

src/interp/iz3interp.h

@@ -43,6 +43,27 @@ struct iz3_bad_tree {
 struct iz3_incompleteness {
 };
 
+// This is thrown if there is some bug in the
+// interpolation procedure
+class interpolation_failure : public default_exception {
+ public:
+ interpolation_failure(const char *msg)
+     : default_exception(msg)
+    {
+    }
+};
+
+// This is thrown if we cannot derive an interpolant from a proof
+// because it contains unsupported theories or if the proof contains
+// errors
+class interpolation_error : public default_exception {
+ public:
+ interpolation_error()
+     : default_exception("theory not supported by interpolation or bad proof" )
+        {
+        }
+};
+
 typedef interpolation_options_struct *interpolation_options;
 
 /* Compute an interpolant from a proof. This version uses the parents vector

src/interp/iz3translate.cpp

@@ -2041,11 +2041,23 @@ public:
             locality.clear();
 #endif
             iproof = iz3proof_itp::create(this,range_downward(i),weak_mode());
-            Iproof::node ipf = translate_main(proof);
-            ast itp = iproof->interpolate(ipf);
-            itps.push_back(itp);
-            delete iproof;
-            clear_translation();
+            try {
+                Iproof::node ipf = translate_main(proof);
+                ast itp = iproof->interpolate(ipf);
+                itps.push_back(itp);
+                delete iproof;
+                clear_translation();
+            }
+            catch (const iz3proof_itp::proof_error &) {
+                delete iproof;
+                clear_translation();
+                throw iz3proof::proof_error();
+            }
+            catch (const unsupported &exc) {
+                delete iproof;
+                clear_translation();
+                throw exc;
+            }
         }
         // Very simple proof -- lemma of the empty clause with computed interpolation
         iz3proof::node Ipf = dst.make_lemma(std::vector<ast>(),itps);  // builds result in dst