[vala] Support derived structs with no fields, report an error otherwise

[Jürg Billeter <juergbi src gnome org>]

commit bf46b34f9e262d29720d7d65191969abc838ba83
Author: Luca Bruno <lethalman88 gmail com>
Date:   Mon Jun 28 10:40:46 2010 +0200

    Support derived structs with no fields, report an error otherwise
    
    Fixes bug 622777.

 codegen/valaccodestructmodule.vala |    8 ++++++--
 vala/valaclass.vala                |    1 +
 vala/valastruct.vala               |   17 +++++++++++++----
 3 files changed, 20 insertions(+), 6 deletions(-)
---
diff --git a/codegen/valaccodestructmodule.vala b/codegen/valaccodestructmodule.vala
index d84cbb7..4b3587a 100644
--- a/codegen/valaccodestructmodule.vala
+++ b/codegen/valaccodestructmodule.vala
@@ -103,9 +103,13 @@ public class Vala.CCodeStructModule : CCodeBaseModule {
 			}
 		}
 
-		decl_space.add_type_declaration (new CCodeTypeDefinition ("struct _%s".printf (st.get_cname ()), new CCodeVariableDeclarator (st.get_cname ())));
+		if (st.base_struct == null) {
+			decl_space.add_type_declaration (new CCodeTypeDefinition ("struct _%s".printf (st.get_cname ()), new CCodeVariableDeclarator (st.get_cname ())));
 
-		decl_space.add_type_definition (instance_struct);
+			decl_space.add_type_definition (instance_struct);
+		} else {
+			decl_space.add_type_declaration (new CCodeTypeDefinition (st.base_struct.get_cname (), new CCodeVariableDeclarator (st.get_cname ())));
+		}
 
 		var function = new CCodeFunction (st.get_dup_function (), st.get_cname () + "*");
 		if (st.is_private_symbol ()) {
diff --git a/vala/valaclass.vala b/vala/valaclass.vala
index 54916c5..91fa016 100644
--- a/vala/valaclass.vala
+++ b/vala/valaclass.vala
@@ -1053,6 +1053,7 @@ public class Vala.Class : ObjectTypeSymbol {
 					if (f.binding == MemberBinding.INSTANCE) {
 						error = true;
 						Report.error (source_reference, "derived compact classes may not have instance fields");
+						break;
 					}
 				}
 			}
diff --git a/vala/valastruct.vala b/vala/valastruct.vala
index bcfa13e..180c67e 100644
--- a/vala/valastruct.vala
+++ b/vala/valastruct.vala
@@ -828,10 +828,19 @@ public class Vala.Struct : TypeSymbol {
 			prop.check (analyzer);
 		}
 
-		if (!external && !external_package && base_type == null && get_fields ().size == 0
-		    && !is_boolean_type () && !is_integer_type () && !is_floating_type ()) {
-			error = true;
-			Report.error (source_reference, "structs cannot be empty: %s".printf(name));
+		if (!external && !external_package) {
+			if (base_type == null && get_fields ().size == 0 && !is_boolean_type () && !is_integer_type () && !is_floating_type ()) {
+				error = true;
+				Report.error (source_reference, "structs cannot be empty: %s".printf(name));
+			} else if (base_type != null) {
+				foreach (Field f in fields) {
+					if (f.binding == MemberBinding.INSTANCE) {
+						error = true;
+						Report.error (source_reference, "derived structs may not have instance fields");
+						break;
+					}
+				}
+			}
 		}
 
 		analyzer.current_source_file = old_source_file;