Nested generate regions are illegal

ivtest/gold/br_gh1117.gold

@@ -0,0 +1 @@
+./ivltests/br_gh1117.v:10: error: generate/endgenerate regions cannot nest.

ivtest/ivltests/br_gh1117.v

@@ -0,0 +1,25 @@
+module top;
+  wire x, y, z;
+  reg in;
+  genvar i;
+
+  generate
+  for (i=0; i<1; i=i+1) begin
+    assign x = in;
+  end
+  generate // This should be an error
+  for (i=0; i<1; i=i+1) begin
+    assign y = in;
+  end
+  endgenerate
+  endgenerate
+
+  generate // This is ok
+  for (i=0; i<1; i=i+1) begin
+    assign z = in;
+  end
+  endgenerate
+
+  initial $display("Failed: should be a compile error!");
+
+endmodule

ivtest/regress-vlg.list

@@ -353,6 +353,7 @@ br_gh788		normal,-gno-io-range-error,-Wno-anachronisms	ivltests gold=br_gh788.go
 br_gh793		normal			ivltests
 br_gh827		normal			ivltests gold=br_gh827.gold
 br_gh889		normal,-gspecify	ivltests gold=br_gh889.gold
+br_gh1117		CE			ivltests gold=br_gh1117.gold
 br_gh1175a		CE			ivltests gold=br_gh1175a.gold
 br_gh1175b		CE			ivltests gold=br_gh1175b.gold
 br_gh1175c		CE			ivltests gold=br_gh1175c.gold

parse.y

@@ -45,6 +45,7 @@ extern void lex_end_table();
 static data_type_t* param_data_type = 0;
 static bool param_is_local = false;
 static bool param_is_type = false;
+static bool in_gen_region = false;
 static std::list<pform_range_t>* specparam_active_range = 0;
 
 /* Port declaration lists use this structure for context. */
@@ -74,6 +75,15 @@ static stack<PBlock*> current_block_stack;
    specified. */
 static LexicalScope::lifetime_t var_lifetime;
 
+static void check_in_gen_region(const struct vlltype &loc)
+{
+      if (in_gen_region) {
+	    cerr << loc << ": error: generate/endgenerate regions cannot nest." << endl;
+	    error_count += 1;
+      }
+      in_gen_region = true;
+}
+
 static pform_name_t* pform_create_this(void)
 {
       name_component_t name (perm_string::literal(THIS_TOKEN));
@@ -5208,15 +5218,7 @@ module_item
      generate/endgenerate regions do not nest. Generate schemes nest,
      but generate regions do not. */
 
-  | K_generate generate_item_list_opt K_endgenerate
+  | K_generate { check_in_gen_region(@1); } generate_item_list_opt K_endgenerate { in_gen_region = false; }
-     { // Test for bad nesting. I understand it, but it is illegal.
-       if (pform_parent_generate()) {
-	     cerr << @1 << ": error: Generate/endgenerate regions cannot nest." << endl;
-	     cerr << @1 << ":      : Try removing optional generate/endgenerate keywords," << endl;
-	     cerr << @1 << ":      : or move them to surround the parent generate scheme." << endl;
-	     error_count += 1;
-	}
-      }
 
   | K_genvar list_of_identifiers ';'
       { pform_genvars(@1, $2); }