Fix bug where recursion depth is not reset on longjmp

src/read.h

@@ -46,7 +46,9 @@
 
 #define TRY_READ \
  if (!STATE(NrError)) { \
+ Int recursionDepth = STATE(RecursionDepth); \
  if (sySetjmp(STATE(ReadJmpError))) { \
+ STATE(RecursionDepth) = recursionDepth; \
  STATE(NrError)++; \
  }\
  }\

tst/testinstall/depth.tst

@@ -0,0 +1,32 @@
+gap> START_TEST("depth.tst");
+
+# We don't know what the recursion depth will be when the test starts,
+# so do relative comparisons.
+gap> curdepth := GetRecursionDepth();;
+gap> GetRecursionDepth() - curdepth;
+0
+gap> dive := function(depth)
+> if depth>1 then
+> dive(depth-1);
+> else
+> Print("Depth ", GetRecursionDepth() - curdepth, "\n");
+> fi;
+> end;;
+gap> dive(10);
+Depth 10
+gap> dive(500);
+Depth 500
+gap> SetRecursionTrapInterval(100);
+gap> dive(500);
+Error, recursion depth trap (100)
+gap> SetRecursionTrapInterval(5000);
+gap> dive(500);
+Depth 500
+
+# Just want an error to occur to check the depth is reset correctly
+gap> IsAbelian(2);
+Error, no method found! For debugging hints type ?Recovery from NoMethodFound
+Error, no 1st choice method found for `IsCommutative' on 1 arguments
+gap> dive(500);
+Depth 500
+gap> STOP_TEST( "depth.tst", 1);