From b89c3bedc5e11632e153e2b62bab1e0f29dc7f8e Mon Sep 17 00:00:00 2001
From: Max Wash <mbswash@gmail.com>
Date: Thu, 8 May 2025 22:32:23 +0100
Subject: [PATCH] lang: ast: add diag for `do` keyword in inline for-loop

---
 lang/ast/for.c               | 21 +++++++++++++++++++++
 lang/diag.c                  |  8 ++++++++
 lang/include/ivy/lang/diag.h |  3 +++
 3 files changed, 32 insertions(+)

diff --git a/lang/ast/for.c b/lang/ast/for.c
index d1b4cd9..c5507d5 100644
--- a/lang/ast/for.c
+++ b/lang/ast/for.c
@@ -81,6 +81,27 @@ static struct token_parse_result parse_do(
 		= parser_get_state(ctx, struct for_parser_state);
 
 	if (state->s_inline) {
+		struct ivy_diag *diag = parser_push_diag(
+			ctx, IVY_LANG_E_INCORRECT_INLINE_FOR_LOOP,
+			IVY_LANG_MSG_DO_UNEXPECTED_IN_INLINE_FOR, tok);
+		ivy_diag_push_msg(
+			diag, IVY_LANG_MSG_PREVIOUS_EXPRESSION_IS_FOR_BODY);
+		const struct ivy_char_cell *x = &state->s_body->n_end;
+		const struct ivy_char_cell *z = &tok->t_end;
+
+		const struct ivy_diag_amendment a[] = {
+			IVY_DIAG_ADD(x->c_row, x->c_col + 1, "."),
+		};
+		const size_t nr_a = sizeof a / sizeof a[0];
+
+		const struct ivy_diag_highlight hl[] = {
+			IVY_DIAG_HL(
+				HINT, x->c_row, x->c_col + 1, x->c_row,
+				x->c_col + 1),
+		};
+		const size_t nr_hl = sizeof hl / sizeof hl[0];
+
+		ivy_diag_push_snippet(diag, x->c_row, z->c_row, a, nr_a, hl, nr_hl);
 		return PARSE_RESULT(IVY_ERR_BAD_SYNTAX, 0);
 	}
 
diff --git a/lang/diag.c b/lang/diag.c
index bcd1fd6..b2124ef 100644
--- a/lang/diag.c
+++ b/lang/diag.c
@@ -8,12 +8,20 @@
 
 static const struct ivy_diag_class diag_classes[] = {
 	ERROR_CLASS(IVY_LANG_E_UNRECOGNISED_SYMBOL, "Unrecognised symbol"),
+	ERROR_CLASS(
+		IVY_LANG_E_INCORRECT_INLINE_FOR_LOOP,
+		"Incorrect inline for-loop"),
 };
 static const size_t nr_diag_classes = sizeof diag_classes / sizeof diag_classes[0];
 
 static const struct ivy_diag_msg diag_msg[] = {
 	MSG(IVY_LANG_MSG_UNKNOWN_SYMBOL_ENCOUNTERED,
             "encountered a symbol that is not part of the Ivy syntax."),
+	MSG(IVY_LANG_MSG_DO_UNEXPECTED_IN_INLINE_FOR,
+            "`[yellow]do[reset]` is not used in inline for-loops."),
+	MSG(IVY_LANG_MSG_PREVIOUS_EXPRESSION_IS_FOR_BODY,
+            "the previous expression is used as the for-loop body. perhaps you "
+            "forgot a [blue]statement separator[reset]?"),
 };
 static const size_t nr_diag_msg = sizeof diag_msg / sizeof diag_msg[0];
 
diff --git a/lang/include/ivy/lang/diag.h b/lang/include/ivy/lang/diag.h
index d6e3209..eda974c 100644
--- a/lang/include/ivy/lang/diag.h
+++ b/lang/include/ivy/lang/diag.h
@@ -8,11 +8,14 @@ struct ivy_diag_ctx;
 enum ivy_lang_diag_code {
 	IVY_LANG_E_NONE = 0,
 	IVY_LANG_E_UNRECOGNISED_SYMBOL,
+	IVY_LANG_E_INCORRECT_INLINE_FOR_LOOP,
 };
 
 enum ivy_lang_diag_msg {
 	IVY_LANG_MSG_NONE = 0,
 	IVY_LANG_MSG_UNKNOWN_SYMBOL_ENCOUNTERED,
+	IVY_LANG_MSG_DO_UNEXPECTED_IN_INLINE_FOR,
+	IVY_LANG_MSG_PREVIOUS_EXPRESSION_IS_FOR_BODY,
 };
 
 IVY_API enum ivy_status ivy_lang_diag_ctx_init(struct ivy_diag_ctx *ctx);