From e2136d60b2db6c714a0c7c84f38bbcad5c519b71 Mon Sep 17 00:00:00 2001
From: Eldred Habert <eldredhabert0@gmail.com>
Date: Mon, 3 Oct 2022 16:50:32 +0200
Subject: [PATCH] Print a more user-friendly error message for leftover diff
 marks (#1089)

---
 src/asm/parser.y | 21 +++++++++++++++------
 1 file changed, 15 insertions(+), 6 deletions(-)

diff --git a/src/asm/parser.y b/src/asm/parser.y
index ee9bb9de..21d6a536 100644
--- a/src/asm/parser.y
+++ b/src/asm/parser.y
@@ -690,17 +690,19 @@ asmfile		: lines
 ;
 
 lines		: %empty
-		| lines line
+		| lines opt_diff_mark line
 ;
 
 endofline	: T_NEWLINE | T_EOB
 ;
 
-plain_directive	: label
-		| label cpu_command
-		| label macro
-		| label directive
-		| assignment_directive
+opt_diff_mark	: %empty // OK
+		| T_OP_ADD {
+			error("syntax error, unexpected + at the beginning of the line (is it a leftover diff mark?)\n");
+		}
+		| T_OP_SUB {
+			error("syntax error, unexpected - at the beginning of the line (is it a leftover diff mark?)\n");
+		}
 ;
 
 line		: plain_directive endofline
@@ -786,6 +788,13 @@ else		: T_POP_ELSE T_NEWLINE {
 		}
 ;
 
+plain_directive	: label
+		| label cpu_command
+		| label macro
+		| label directive
+		| assignment_directive
+;
+
 endc		: T_POP_ENDC {
 			lexer_DecIFDepth();
 		}