handle Zipperposition's ResourceOut gracefully

--- a/src/HOL/Tools/ATP/atp_proof.ML	Fri Aug 27 14:28:56 2021 +0200
+++ b/src/HOL/Tools/ATP/atp_proof.ML	Fri Aug 27 14:29:02 2021 +0200
@@ -157,32 +157,31 @@
 fun from_lemmas [] = ""
   | from_lemmas ss = " from " ^ space_implode " " (Try.serial_commas "and" (map quote ss))
 
-fun string_of_atp_failure MaybeUnprovable = "The generated problem is maybe unprovable"
-  | string_of_atp_failure Unprovable = "The generated problem is unprovable"
-  | string_of_atp_failure GaveUp = "The prover gave up"
+fun string_of_atp_failure MaybeUnprovable = "Problem maybe unprovable"
+  | string_of_atp_failure Unprovable = "Unprovable problem"
+  | string_of_atp_failure GaveUp = "Gave up"
   | string_of_atp_failure ProofMissing =
-    "The prover claims the conjecture is a theorem but did not provide a proof"
+    "Claims the conjecture is a theorem but did not provide a proof"
   | string_of_atp_failure ProofIncomplete =
-    "The prover claims the conjecture is a theorem but provided an incomplete proof"
+    "Claims the conjecture is a theorem but provided an incomplete proof"
   | string_of_atp_failure ProofUnparsable =
-    "The prover claims the conjecture is a theorem but provided an unparsable proof"
+    "Claims the conjecture is a theorem but provided an unparsable proof"
   | string_of_atp_failure (UnsoundProof (false, ss)) =
-    "The prover derived the lemma \"False\"" ^ from_lemmas ss ^
-    "; specify a sound type encoding or omit the \"type_enc\" option"
+    "Derived the lemma \"False\"" ^ from_lemmas ss ^
+    ", probably due to the use of an unsound type encoding"
   | string_of_atp_failure (UnsoundProof (true, ss)) =
-    "The prover derived the lemma \"False\"" ^ from_lemmas ss ^
+    "Derived the lemma \"False\"" ^ from_lemmas ss ^
     ", which could be due to a bug in Sledgehammer or to inconsistent axioms (including \"sorry\"s)"
   | string_of_atp_failure TimedOut = "Timed out"
-  | string_of_atp_failure Inappropriate =
-    "The generated problem lies outside the prover's scope"
-  | string_of_atp_failure OutOfResources = "The prover ran out of resources"
-  | string_of_atp_failure MalformedInput = "The generated problem is malformed"
-  | string_of_atp_failure MalformedOutput = "The prover output is malformed"
-  | string_of_atp_failure Interrupted = "The prover was interrupted"
-  | string_of_atp_failure Crashed = "The prover crashed"
-  | string_of_atp_failure InternalError = "An internal prover error occurred"
+  | string_of_atp_failure Inappropriate = "Problem outside the prover's scope"
+  | string_of_atp_failure OutOfResources = "Ran out of resources"
+  | string_of_atp_failure MalformedInput = "Malformed problem"
+  | string_of_atp_failure MalformedOutput = "Malformed output"
+  | string_of_atp_failure Interrupted = "Interrupted"
+  | string_of_atp_failure Crashed = "Crashed"
+  | string_of_atp_failure InternalError = "Internal prover error"
   | string_of_atp_failure (UnknownError s) =
-    "A prover error occurred" ^
+    "Prover error" ^
     (if s = "" then " (pass the \"verbose\" option for details)" else ":\n" ^ s)
 
 fun extract_delimited (begin_delim, end_delim) output =

--- a/src/HOL/Tools/Sledgehammer/sledgehammer_atp_systems.ML	Fri Aug 27 14:28:56 2021 +0200
+++ b/src/HOL/Tools/Sledgehammer/sledgehammer_atp_systems.ML	Fri Aug 27 14:29:02 2021 +0200
@@ -557,7 +557,9 @@
        ["--input tptp --output tptp --timeout " ^ string_of_int (to_secs 1 timeout) ^ " " ^ File.bash_path problem
         |> extra_options <> "" ? prefix (extra_options ^ " ")],
      proof_delims = tstp_proof_delims,
-     known_failures = known_szs_status_failures,
+     known_failures =
+       [(TimedOut, "SZS status ResourceOut")] @   (* odd way of timing out *)
+       known_szs_status_failures,
      prem_role = Hypothesis,
      best_slices = fn _ =>
        (* FUDGE *)