patch 9.0.1209: getting interface member does not always work

Problem:    Getting interface member does not always work.
Solution:   Convert the index on the interface to the index on the object.
            (closes #11825)

src/proto/vim9class.pro

@@ -1,4 +1,5 @@
 /* vim9class.c */
+int object_index_from_itf_index(class_T *itf, int idx, class_T *cl);
 void ex_class(exarg_T *eap);
 type_T *class_member_type(class_T *cl, char_u *name, char_u *name_end, int *member_idx);
 void ex_enum(exarg_T *eap);

src/proto/vim9instr.pro

@@ -5,6 +5,7 @@ isn_T *generate_instr_type(cctx_T *cctx, isntype_T isn_type, type_T *type);
 isn_T *generate_instr_debug(cctx_T *cctx);
 int generate_CONSTRUCT(cctx_T *cctx, class_T *cl);
 int generate_GET_OBJ_MEMBER(cctx_T *cctx, int idx, type_T *type);
+int generate_GET_ITF_MEMBER(cctx_T *cctx, class_T *itf, int itf_idx, type_T *type);
 int generate_STORE_THIS(cctx_T *cctx, int idx);
 int may_generate_2STRING(int offset, int tolerant, cctx_T *cctx);
 int generate_add_instr(cctx_T *cctx, vartype_T vartype, type_T *type1, type_T *type2, exprtype_T expr_type);

src/structs.h

@@ -1483,6 +1483,14 @@ typedef struct {
     char_u	*ocm_init;   // allocated
 } ocmember_T;
 
+// used for the lookup table of a class member index
+typedef struct itf2class_S itf2class_T;
+struct itf2class_S {
+    itf2class_T	*i2c_next;
+    class_T	*i2c_class;
+    // array with ints follows
+};
+
 #define CLASS_INTERFACE 1
 
 // "class_T": used for v_class of typval of VAR_CLASS
@@ -1501,6 +1509,7 @@ struct class_S
     int		class_interface_count;
     char_u	**class_interfaces;	// allocated array of names
     class_T	**class_interfaces_cl;	// interfaces (counts as reference)
+    itf2class_T	*class_itf2class;	// member index lookup tables
 
     // class members: "static varname"
     int		class_class_member_count;

src/testdir/test_vim9_class.vim

@@ -870,6 +870,32 @@ def Test_class_implements_interface()
       endclass
   END
   v9.CheckScriptFailure(lines, 'E1349: Function "Methods" of interface "Some" not implemented')
+
+  # Check different order of members in class and interface works.
+  lines =<< trim END
+      vim9script
+
+      interface Result
+        this.label: string
+        this.errpos: number
+      endinterface
+
+      # order of members is opposite of interface
+      class Failure implements Result
+        this.errpos: number = 42
+        this.label: string = 'label'
+      endclass
+
+      def Test()
+        var result: Result = Failure.new()
+
+        assert_equal('label', result.label)
+        assert_equal(42, result.errpos)
+      enddef
+
+      Test()
+  END
+  v9.CheckScriptSuccess(lines)
 enddef
 
 def Test_class_used_as_type()

src/version.c

@@ -695,6 +695,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1209,
 /**/
     1208,
 /**/

src/vim9.h

@@ -34,10 +34,11 @@ typedef enum {
     ISN_INSTR,	    // instructions compiled from expression
     ISN_CONSTRUCT,  // construct an object, using contstruct_T
     ISN_GET_OBJ_MEMBER, // object member, index is isn_arg.number
+    ISN_GET_ITF_MEMBER, // interface member, index is isn_arg.classmember
     ISN_STORE_THIS, // store value in "this" object member, index is
 		    // isn_arg.number
-    ISN_LOAD_CLASSMEMBER,  // load class member, using classmember_T
-    ISN_STORE_CLASSMEMBER,  // store in class member, using classmember_T
+    ISN_LOAD_CLASSMEMBER,  // load class member, using isn_arg.classmember
+    ISN_STORE_CLASSMEMBER,  // store in class member, using isn_arg.classmember
 
     // get and set variables
     ISN_LOAD,	    // push local variable isn_arg.number
@@ -480,7 +481,7 @@ typedef struct {
     class_T	*construct_class;   // class the object is created from
 } construct_T;
 
-// arguments to ISN_STORE_CLASSMEMBER and ISN_LOAD_CLASSMEMBER
+// arguments to ISN_STORE_CLASSMEMBER, ISN_LOAD_CLASSMEMBER, ISN_GET_ITF_MEMBER
 typedef struct {
     class_T	*cm_class;
     int		cm_idx;

src/vim9class.c

@@ -196,6 +196,32 @@ add_members_to_class(
     return OK;
 }
 
+/*
+ * Convert a member index "idx" of interface "itf" to the member index of class
+ * "cl" implementing that interface.
+ */
+    int
+object_index_from_itf_index(class_T *itf, int idx, class_T *cl)
+{
+    if (idx > itf->class_obj_member_count)
+    {
+	siemsg("index %d out of range for interface %s", idx, itf->class_name);
+	return 0;
+    }
+    itf2class_T *i2c;
+    for (i2c = itf->class_itf2class; i2c != NULL; i2c = i2c->i2c_next)
+	if (i2c->i2c_class == cl)
+	    break;
+    if (i2c == NULL)
+    {
+	siemsg("class %s not found on interface %s",
+					      cl->class_name, itf->class_name);
+	return 0;
+    }
+    int *table = (int *)(i2c + 1);
+    return table[idx];
+}
+
 /*
  * Handle ":class" and ":abstract class" up to ":endclass".
  * Handle ":interface" up to ":endinterface".
@@ -765,22 +791,6 @@ early_ret:
 
 	cl->class_extends = extends_cl;
 
-	if (ga_impl.ga_len > 0)
-	{
-	    // Move the "implements" names into the class.
-	    cl->class_interface_count = ga_impl.ga_len;
-	    cl->class_interfaces = ALLOC_MULT(char_u *, ga_impl.ga_len);
-	    if (cl->class_interfaces == NULL)
-		goto cleanup;
-	    for (int i = 0; i < ga_impl.ga_len; ++i)
-		cl->class_interfaces[i] = ((char_u **)ga_impl.ga_data)[i];
-	    VIM_CLEAR(ga_impl.ga_data);
-	    ga_impl.ga_len = 0;
-
-	    cl->class_interfaces_cl = intf_classes;
-	    intf_classes = NULL;
-	}
-
 	// Add class and object members to "cl".
 	if (add_members_to_class(&classmembers,
 				 extends_cl == NULL ? NULL
@@ -798,6 +808,48 @@ early_ret:
 				 &cl->class_obj_member_count) == FAIL)
 	    goto cleanup;
 
+	if (ga_impl.ga_len > 0)
+	{
+	    // Move the "implements" names into the class.
+	    cl->class_interface_count = ga_impl.ga_len;
+	    cl->class_interfaces = ALLOC_MULT(char_u *, ga_impl.ga_len);
+	    if (cl->class_interfaces == NULL)
+		goto cleanup;
+	    for (int i = 0; i < ga_impl.ga_len; ++i)
+		cl->class_interfaces[i] = ((char_u **)ga_impl.ga_data)[i];
+	    VIM_CLEAR(ga_impl.ga_data);
+	    ga_impl.ga_len = 0;
+
+	    // For each interface add a lookuptable for the member index on the
+	    // interface to the member index in this class.
+	    for (int i = 0; i < cl->class_interface_count; ++i)
+	    {
+		class_T *ifcl = intf_classes[i];
+		itf2class_T *if2cl = alloc_clear(sizeof(itf2class_T)
+				 + ifcl->class_obj_member_count * sizeof(int));
+		if (if2cl == NULL)
+		    goto cleanup;
+		if2cl->i2c_next = ifcl->class_itf2class;
+		ifcl->class_itf2class = if2cl;
+		if2cl->i2c_class = cl;
+
+		for (int if_i = 0; if_i < ifcl->class_obj_member_count; ++if_i)
+		    for (int cl_i = 0; cl_i < cl->class_obj_member_count; ++cl_i)
+		    {
+			if (STRCMP(ifcl->class_obj_members[if_i].ocm_name,
+				     cl->class_obj_members[cl_i].ocm_name) == 0)
+			{
+			    int *table = (int *)(if2cl + 1);
+			    table[if_i] = cl_i;
+			    break;
+			}
+		    }
+	    }
+
+	    cl->class_interfaces_cl = intf_classes;
+	    intf_classes = NULL;
+	}
+
 	if (is_class && cl->class_class_member_count > 0)
 	{
 	    // Allocate a typval for each class member and initialize it.
@@ -1411,6 +1463,13 @@ class_unref(class_T *cl)
 	vim_free(cl->class_interfaces);
 	vim_free(cl->class_interfaces_cl);
 
+	itf2class_T *next;
+	for (itf2class_T *i2c = cl->class_itf2class; i2c != NULL; i2c = next)
+	{
+	    next = i2c->i2c_next;
+	    vim_free(i2c);
+	}
+
 	for (int i = 0; i < cl->class_class_member_count; ++i)
 	{
 	    ocmember_T *m = &cl->class_class_members[i];

src/vim9compile.c

@@ -2056,6 +2056,8 @@ compile_load_lhs_with_index(lhs_T *lhs, char_u *var_start, cctx_T *cctx)
 
 	if (generate_LOAD(cctx, ISN_LOAD, 0, NULL, lhs->lhs_type) == FAIL)
 	    return FAIL;
+	if (cl->class_flags & CLASS_INTERFACE)
+	    return generate_GET_ITF_MEMBER(cctx, cl, lhs->lhs_member_idx, type);
 	return generate_GET_OBJ_MEMBER(cctx, lhs->lhs_member_idx, type);
     }
 

src/vim9execute.c

@@ -5184,6 +5184,7 @@ exec_instructions(ectx_T *ectx)
 		break;
 
 	    case ISN_GET_OBJ_MEMBER:
+	    case ISN_GET_ITF_MEMBER:
 		{
 		    tv = STACK_TV_BOT(-1);
 		    if (tv->v_type != VAR_OBJECT)
@@ -5200,8 +5201,20 @@ exec_instructions(ectx_T *ectx)
 			clear_type_list(&type_list);
 			goto on_error;
 		    }
-		    int idx = iptr->isn_arg.number;
+
 		    object_T *obj = tv->vval.v_object;
+		    int idx;
+		    if (iptr->isn_type == ISN_GET_OBJ_MEMBER)
+			idx = iptr->isn_arg.number;
+		    else
+		    {
+			idx = iptr->isn_arg.classmember.cm_idx;
+			// convert the interface index to the object index
+			idx = object_index_from_itf_index(
+					      iptr->isn_arg.classmember.cm_class,
+					      idx, obj->obj_class);
+		    }
+
 		    // the members are located right after the object struct
 		    typval_T *mtv = ((typval_T *)(obj + 1)) + idx;
 		    copy_tv(mtv, tv);
@@ -6912,6 +6925,11 @@ list_instructions(char *pfx, isn_T *instr, int instr_count, ufunc_T *ufunc)
 						  iptr->isn_arg.string); break;
 	    case ISN_GET_OBJ_MEMBER: smsg("%s%4d OBJ_MEMBER %d", pfx, current,
 					     (int)iptr->isn_arg.number); break;
+	    case ISN_GET_ITF_MEMBER: smsg("%s%4d ITF_MEMBER %d on %s",
+			     pfx, current,
+			     (int)iptr->isn_arg.classmember.cm_idx,
+			     iptr->isn_arg.classmember.cm_class->class_name);
+				     break;
 	    case ISN_STORE_THIS: smsg("%s%4d STORE_THIS %d", pfx, current,
 					     (int)iptr->isn_arg.number); break;
 	    case ISN_CLEARDICT: smsg("%s%4d CLEARDICT", pfx, current); break;

src/vim9expr.c

@@ -364,6 +364,8 @@ compile_class_object_index(cctx_T *cctx, char_u **arg, type_T *type)
 		}
 
 		*arg = name_end;
+		if (cl->class_flags & CLASS_INTERFACE)
+		    return generate_GET_ITF_MEMBER(cctx, cl, i, m->ocm_type);
 		return generate_GET_OBJ_MEMBER(cctx, i, m->ocm_type);
 	    }
 	}

src/vim9instr.c

@@ -149,6 +149,26 @@ generate_GET_OBJ_MEMBER(cctx_T *cctx, int idx, type_T *type)
     return push_type_stack2(cctx, type, &t_any);
 }
 
+/*
+ * Generate ISN_GET_ITF_MEMBER - access member of interface at bottom of stack
+ * by index.
+ */
+    int
+generate_GET_ITF_MEMBER(cctx_T *cctx, class_T *itf, int idx, type_T *type)
+{
+    RETURN_OK_IF_SKIP(cctx);
+
+    // drop the object type
+    isn_T *isn = generate_instr_drop(cctx, ISN_GET_ITF_MEMBER, 1);
+    if (isn == NULL)
+	return FAIL;
+
+    isn->isn_arg.classmember.cm_class = itf;
+    ++itf->class_refcount;
+    isn->isn_arg.classmember.cm_idx = idx;
+    return push_type_stack2(cctx, type, &t_any);
+}
+
 /*
  * Generate ISN_STORE_THIS - store value in member of "this" object with member
  * index "idx".
@@ -2497,6 +2517,7 @@ delete_instr(isn_T *isn)
 
 	case ISN_LOAD_CLASSMEMBER:
 	case ISN_STORE_CLASSMEMBER:
+	case ISN_GET_ITF_MEMBER:
 	    class_unref(isn->isn_arg.classmember.cm_class);
 	    break;