hoa: add some error recovery

* src/hoaparse/hoaparse.yy: Here.
* src/tgbatest/hoaparse.test: More tests.

src/hoaparse/hoaparse.yy

@@ -144,6 +144,16 @@ hoa: header "--BODY--" body "--END--"
        res.h->loc = @$;
        YYACCEPT;
      }
+hoa: error "--END--"
+     {
+       res.h->loc = @$;
+       YYACCEPT;
+     }
+hoa: error ENDOFFILE
+     {
+       res.h->loc = @$;
+       YYACCEPT;
+     }
 hoa: ENDOFFILE { YYABORT; }
 
 string_opt: | STRING
@@ -173,12 +183,18 @@ header: format-version header-items
 	    }
 	}
 
-format-version: "HOA:" { res.h->loc = @1; } IDENTIFIER
+version: IDENTIFIER
-		{
+         {
-		  if (*$3 != "v1")
+	   if (*$1 != "v1")
-		    error(@$, "unsupported version of the HOA format");
+	     error(@$, "unsupported version of the HOA format");
-		  delete $3;
+	   delete $1;
-		}
+	 }
+
+format-version: "HOA:" { res.h->loc = @1; } version
+              | error "HOA:"
+	        { error(@1, "ignoring leading garbage");
+		  res.h->loc = @2; }
+                version
 
 header-items: | header-items header-item
 header-item: "States:" INT
@@ -295,6 +311,7 @@ header-item: "States:" INT
 		       " be ignored)");
 	       delete $1;
 	     }
+           | error
 
 ap-names: | ap-names ap-name
 ap-name: STRING
@@ -500,6 +517,8 @@ state: state-name labeled-edges
 	     res.cur_guard = res.guards.begin();
 	   }
        }
+     | error
+
 state-name: "State:" state-label_opt checked-state-num string_opt acc-sig_opt
 	  {
 	    res.cur_state = $3;
@@ -517,6 +536,11 @@ label: '[' label-expr ']'
              res.cur_label = bdd_from_int($2);
              bdd_delref($2);
 	   }
+     | '[' error ']'
+           {
+	     error(@$, "ignoring this invalid label");
+	     res.cur_label = bddtrue;
+	   }
 state-label_opt:       { res.has_state_label = false; }
                | label { res.has_state_label = true;
                          res.state_label_loc = @1;
@@ -547,6 +571,10 @@ acc-sig_opt:
 		   res.ignore_acc_silent = true;
 		 }
 	     }
+           | '{' error '}'
+	     {
+	       error(@$, "ignoring this invalid acceptance set");
+	     }
 acc-sets:
           {
 	    $$ = spot::acc_cond::mark_t(0U);

src/tgbatest/hoaparse.test

@@ -223,7 +223,7 @@ EOF
 expecterr input <<EOF
 input:5.19: number is larger than the count of acceptance sets...
 input:5.1-13: ... declared here.
-input:12.1-7: unsupported version of the HOA format
+input:12.6-7: unsupported version of the HOA format
 input:12.1-7: missing 'Acceptance:' header
 EOF
 
@@ -560,3 +560,61 @@ State: 1
 EOF
 
 diff expected input.out
+
+
+# Error recovery
+
+cat >input <<EOF
+HOA: v1
+States: 2
+Start: 0
+AP: 0
+acc-name: Buchi
+Acceptance: 1 Inf(0)
+--BODY--
+State: 0 {a}  /* not a digit */
+[t] 1
+State: 1
+[a] 0         /* not a digit */
+--END--
+HOA: v1
+Acceptance: 1 Inf(0)
+States: 2
+Start: 0
+AP: 0
+acc-name: Buchi
+--BODY--
+State: 0 {0}
+[t] "f" 1     /* WTF? */
+State: 1
+[t] 0
+--END--
+some garbage HOA: v1
+Acceptance: 1 Inf(0)
+States: 2
+Start: 0
+AP: 0
+acc-name: Buchi
+--BODY--
+Stat: 0 {0}  /* not State: */
+[t] 1
+State: 1
+[t] 0
+--END--
+this is complete garbage!
+--END--
+and even more garbage
+EOF
+
+expecterr input <<EOF
+input:8.11: syntax error, unexpected identifier, expecting integer or '}'
+input:8.10-12: ignoring this invalid acceptance set
+input:11.2: syntax error, unexpected identifier
+input:11.1-3: ignoring this invalid label
+input:21.5-7: syntax error, unexpected string, expecting integer
+input:25.1-4: syntax error, unexpected identifier, expecting end of file or HOA:
+input:25.1-12: ignoring leading garbage
+input:32.1-5: syntax error, unexpected header name, expecting --END-- or State:
+input:37.1-4: syntax error, unexpected identifier, expecting end of file or HOA:
+input:39.1-3: syntax error, unexpected identifier, expecting end of file or HOA:
+EOF