kernel: insert a few SET_BRK_CALL_TO(stat) calls

After evaluating the body of a loop resp. an if-statmeent, and before
evaluating the next condition expression, reset the current statement to
point to the loop resp. if-statement again.

src/stats.c

@@ -240,6 +240,8 @@ UInt            ExecIfElse (
 
     }
 
+    SET_BRK_CALL_TO(stat);
+
     /* otherwise execute the else-branch body and leave                    */
     body = READ_STAT(stat, 3);
     return EXEC_STAT( body );
@@ -269,6 +271,7 @@ UInt            ExecIfElif (
 
         }
 
+        SET_BRK_CALL_TO(stat);
     }
 
     /* return 0 (to indicate that no leave-statement was executed)         */
@@ -299,6 +302,7 @@ UInt            ExecIfElifElse (
 
         }
 
+        SET_BRK_CALL_TO(stat);
     }
 
     /* otherwise execute the else-branch body and leave                    */
@@ -689,6 +693,7 @@ static ALWAYS_INLINE UInt ExecWhileHelper(Stat stat, UInt nr)
         if (nr >= 3)
             EXEC_STAT_IN_LOOP(body3);
 
+        SET_BRK_CALL_TO(stat);
     }
 
     /* return 0 (to indicate that no leave-statement was executed)         */
@@ -760,6 +765,8 @@ static ALWAYS_INLINE UInt ExecRepeatHelper(Stat stat, UInt nr)
         if (nr >= 3)
             EXEC_STAT_IN_LOOP(body3);
 
+        SET_BRK_CALL_TO(stat);
+
     } while ( EVAL_BOOL_EXPR( cond ) == False );
 
     /* return 0 (to indicate that no leave-statement was executed)         */

tst/testspecial/backtrace.g.out

@@ -64,7 +64,11 @@ gap>
 gap> f:=function() if 1 < 0 then return 1; elif 1 then return 2; fi; return 3; end;;
 gap> f();
 Error, <expr> must be 'true' or 'false' (not a integer) in
-  1 < 0 at *stdin*:18 called from 
+  if 1 < 0 then
+    return 1;
+elif 1 then
+    return 2;
+fi; at *stdin*:18 called from 
 <function "f">( <arguments> )
  called from read-eval loop at *stdin*:19
 you can replace <expr> via 'return <expr>;'
@@ -130,7 +134,9 @@ gap>
 gap> f:=function() local x; repeat x:=1; until 1; return 2; end;;
 gap> f();
 Error, <expr> must be 'true' or 'false' (not a integer) in
-  x := 1; at *stdin*:30 called from 
+  repeat
+    x := 1;
+until 1; at *stdin*:30 called from 
 <function "f">( <arguments> )
  called from read-eval loop at *stdin*:31
 you can replace <expr> via 'return <expr>;'