Cleaner error message when missing comma in struct initializer #1941.

releasenotes.md

@@ -17,6 +17,7 @@
 - Improve error message when using ',' in struct declarations. #1920
 - Compile time array assign ops, e.g. `$c[1] += 3` #1890.
 - Add `inline` to enums #1819.
+- Cleaner error message when missing comma in struct initializer #1941.
 
 ### Fixes
 - Fix issue requiring prefix on a generic interface declaration.

src/compiler/parse_expr.c

@@ -138,6 +138,10 @@ inline Expr *parse_precedence_with_left_side(ParseContext *c, Expr *left_side, P
 		if (precedence > token_precedence) break;
 		// LHS may be poison.
 		if (!expr_ok(left_side)) return left_side;
+
+		// Special rule to prevent = {}.
+		if (tok == TOKEN_DOT && left_side->expr_kind == EXPR_INITIALIZER_LIST) break;
+
 		// See if there is a rule for infix.
 		ParseFn infix_rule = rules[tok].infix;
 		// Otherwise we ran into a symbol that can't appear in this position.
@@ -912,7 +916,11 @@ Expr *parse_initializer_list(ParseContext *c, Expr *left)
 			}
 			designated = 0;
 		}
-		CONSUME_OR_RET(TOKEN_RBRACE, poisoned_expr);
+		if (!try_consume(c, TOKEN_RBRACE))
+		{
+			PRINT_ERROR_HERE("A comma or '}' was expected here.");
+			return poisoned_expr;
+		}
 		RANGE_EXTEND_PREV(initializer_list);
 		if (designated == 1)
 		{

src/compiler/parse_global.c

@@ -2393,6 +2393,11 @@ static inline Decl *parse_enum_declaration(ParseContext *c)
 		// Allow trailing ','
 		if (!try_consume(c, TOKEN_COMMA))
 		{
+			if (tok_is(c, TOKEN_CONST_IDENT))
+			{
+				PRINT_ERROR_HERE("It looks like you forgot a comma before this identifier.");
+				return poisoned_decl;
+			}
 			EXPECT_OR_RET(TOKEN_RBRACE, poisoned_decl);
 		}
 	}

test/test_suite/enumerations/enum_missing_comma.c3

@@ -0,0 +1,5 @@
+enum Abc
+{
+	FOO
+	BAR // #error: It looks like you forgot a comma
+}

test/test_suite/initialize/initializer_access.c3

@@ -0,0 +1,10 @@
+module test;
+struct Abc
+{
+	int[2] a;
+	int b;
+}
+fn int main()
+{
+	Abc a = { .a = {} .b = 3 }; // #error: A comma or '}' was expected here.
+}