diff --git a/lang/ast/ctx.c b/lang/ast/ctx.c
index f1c53a0..4b603d2 100644
--- a/lang/ast/ctx.c
+++ b/lang/ast/ctx.c
@@ -4,6 +4,7 @@
 #include "node.h"
 
 #include <blue/core/queue.h>
+#include <ivy/diag.h>
 #include <ivy/lang/ast.h>
 #include <stddef.h>
 #include <stdio.h>
@@ -67,6 +68,13 @@ void ivy_parser_destroy(struct ivy_parser *parser, struct ivy_ast_node **result)
 	free(parser);
 }
 
+enum ivy_status ivy_parser_set_diag_ctx(
+	struct ivy_parser *parser, struct ivy_diag_ctx *ctx)
+{
+	parser->p_diag_ctx = ctx;
+	return IVY_OK;
+}
+
 enum ivy_status ivy_parser_get_status(struct ivy_parser *parser)
 {
 	return parser->p_status;
@@ -266,3 +274,30 @@ struct ivy_ast_node *ivy_parser_dequeue_node(struct ivy_parser *parser)
 
 	return b_unbox(struct ivy_ast_node, entry, n_entry);
 }
+
+struct ivy_diag *parser_push_diag(
+	struct ivy_parser *parser, unsigned long diag_class, unsigned long msg,
+	struct ivy_token *tok)
+{
+	struct ivy_diag *diag
+		= ivy_diag_ctx_create_diag(parser->p_diag_ctx, diag_class);
+
+	if (msg != 0) {
+		ivy_diag_push_msg(diag, msg);
+	}
+
+	if (tok) {
+		const struct ivy_diag_highlight hl[] = {
+			IVY_DIAG_HL(
+				ERROR, tok->t_start.c_row, tok->t_start.c_col,
+				tok->t_end.c_row, tok->t_end.c_col),
+		};
+		const size_t nr_hl = sizeof hl / sizeof hl[0];
+
+		ivy_diag_push_snippet(
+			diag, tok->t_start.c_row, tok->t_end.c_row, NULL, 0, hl,
+			nr_hl);
+	};
+
+	return diag;
+}
diff --git a/lang/ast/ctx.h b/lang/ast/ctx.h
index 9e96379..475563d 100644
--- a/lang/ast/ctx.h
+++ b/lang/ast/ctx.h
@@ -2,7 +2,9 @@
 #define _AST_CTX_H_
 
 #include <blue/core/queue.h>
+#include <ivy/diag.h>
 #include <ivy/lang/ast.h>
+#include <ivy/lang/diag.h>
 #include <ivy/status.h>
 
 #define parser_get_state(parser, state_type)                                   \
@@ -19,6 +21,7 @@ struct parser_state {
 
 struct ivy_parser {
 	enum ivy_status p_status;
+	struct ivy_diag_ctx *p_diag_ctx;
 	b_queue p_state;
 	b_queue p_token_queue;
 	b_queue p_node_queue;
@@ -40,4 +43,8 @@ extern void parser_replace_current_node(
 extern enum ivy_status parser_add_child(
 	struct ivy_parser *parser, struct ivy_ast_node *new_node);
 
+extern struct ivy_diag *parser_push_diag(
+	struct ivy_parser *parser, unsigned long diag_class, unsigned long msg,
+	struct ivy_token *tok);
+
 #endif
diff --git a/lang/ast/node.c b/lang/ast/node.c
index 9b59c61..c25a6dc 100644
--- a/lang/ast/node.c
+++ b/lang/ast/node.c
@@ -250,6 +250,39 @@ void ivy_ast_node_to_string(struct ivy_ast_node *node, struct b_string *out)
 	}
 }
 
+void ivy_ast_node_set_bounds_from_token(
+	struct ivy_ast_node *parent, const struct ivy_token *tok)
+{
+	parent->n_start = tok->t_start;
+	parent->n_end = tok->t_end;
+}
+
+void ivy_ast_node_extend_bounds(
+	struct ivy_ast_node *parent, const struct ivy_ast_node *child)
+{
+	if (child->n_start.c_row < parent->n_start.c_row) {
+		parent->n_start = child->n_start;
+	} else if (child->n_start.c_col < parent->n_start.c_col) {
+		parent->n_start.c_col = child->n_start.c_col;
+	}
+
+	if (child->n_end.c_row > parent->n_end.c_row) {
+		parent->n_end = child->n_end;
+	} else if (child->n_end.c_col > parent->n_end.c_col) {
+		parent->n_end.c_col = child->n_end.c_col;
+	}
+}
+
+void ivy_ast_node_extend_bounds_recursive(
+	struct ivy_ast_node *parent, const struct ivy_ast_node *child)
+{
+	while (parent) {
+		ivy_ast_node_extend_bounds(parent, child);
+		child = parent;
+		parent = parent->n_parent;
+	}
+}
+
 void ivy_ast_node_destroy(struct ivy_ast_node *node)
 {
 	struct ivy_ast_node_iterator it = {};
diff --git a/lang/include/ivy/lang/ast.h b/lang/include/ivy/lang/ast.h
index cabe5d5..2cfd8e7 100644
--- a/lang/include/ivy/lang/ast.h
+++ b/lang/include/ivy/lang/ast.h
@@ -7,6 +7,7 @@
 #include <ivy/misc.h>
 #include <ivy/status.h>
 
+struct ivy_diag_ctx;
 struct ivy_token;
 struct ivy_parser;
 struct b_string;
@@ -72,6 +73,8 @@ struct ivy_ast_node_iterator_entry {
 
 struct ivy_ast_node {
 	enum ivy_ast_node_type n_type;
+	struct ivy_ast_node *n_parent;
+	struct ivy_char_cell n_start, n_end;
 	b_queue_entry n_entry;
 	struct ivy_ast_node_iterator_entry n_it;
 };
@@ -332,6 +335,8 @@ IVY_API enum ivy_status ivy_parser_create(struct ivy_parser **parser);
 IVY_API void ivy_parser_destroy(
 	struct ivy_parser *parser, struct ivy_ast_node **result);
 
+IVY_API enum ivy_status ivy_parser_set_diag_ctx(
+	struct ivy_parser *parser, struct ivy_diag_ctx *ctx);
 IVY_API enum ivy_status ivy_parser_get_status(struct ivy_parser *parser);
 IVY_API bool ivy_parser_is_node_complete(struct ivy_parser *parser);
 IVY_API struct ivy_ast_node *ivy_parser_root_node(struct ivy_parser *parser);
@@ -345,6 +350,12 @@ IVY_API enum ivy_status ivy_ast_node_iterate(
 	struct ivy_ast_node *node, struct ivy_ast_node_iterator *it,
 	ivy_ast_node_iteration_callback callback, void *arg);
 IVY_API void ivy_ast_node_to_string(struct ivy_ast_node *node, struct b_string *out);
+IVY_API void ivy_ast_node_set_bounds_from_token(
+	struct ivy_ast_node *parent, const struct ivy_token *tok);
+IVY_API void ivy_ast_node_extend_bounds(
+	struct ivy_ast_node *parent, const struct ivy_ast_node *child);
+IVY_API void ivy_ast_node_extend_bounds_recursive(
+	struct ivy_ast_node *parent, const struct ivy_ast_node *child);
 IVY_API void ivy_ast_node_destroy(struct ivy_ast_node *node);
 
 IVY_API const char *ivy_ast_node_type_to_string(enum ivy_ast_node_type v);