Make void functions return a dummy value.

This means void and non-void functions are called the same way, which
means non-void functions can be cast to void functions.

1 files changed, 18 insertions, 4 deletions

diff --git a/graph.c b/graph.c
index 5ddabd8..837a2d8 100644
--- a/graph.c
+++ b/graph.c
@@ -52,6 +52,23 @@ graph_function (ast_function_definition_t *function)
 
     node = node_insert_after (function->end, node);
     node = node_insert_after (function->exit, node);
+
+    if (function->type_spec->common.type == AST_VOID_TYPE)
+    {
+	/* Dummy return value. This is useful because it means
+	 * function calls will always leave something on the
+	 * stack. That mean void functions are called in the
+	 * same way as non-void functions, and that makes
+	 * it possible to cast non-void function pointers to
+	 * void function pointers
+	 */
+	value_t value;
+
+	value.int32_val = 0;
+
+	node = node_new_literal (value, function->type_spec, node, ast);
+    }
+    
     node = node_new_return (function->return_type, node, ast);
     node->common.reachable = TRUE;
 }
@@ -276,7 +293,6 @@ graph_expression (ast_expression_t *expr,
 	g_assert (id->definition);
 
 	node = generate_load (id->definition, expr, FALSE, node, ast);
-
 	break;
 
     case AST_INT_LITERAL_EXPRESSION:
@@ -710,9 +726,7 @@ graph_statement (ast_statement_t *statement,
 
     case AST_EXPRESSION_STATEMENT:
 	node = graph_expression (statement->expression.expr, node);
-
-	if (statement->expression.expr->common.type_spec->common.type != AST_VOID_TYPE)
-	    node = node_new_pop (node, ast);
+	node = node_new_pop (node, ast);
 	break;
 
     case AST_RETURN_STATEMENT: