- Second value in switch range not checked properly, causing an error on non-const values. #2777

releasenotes.md

@@ -21,6 +21,7 @@
 - Create optional with `~` instead of `?`. `return io::EOF?;` becomes `return io::EOF~`.
 - Deprecated use of `?` to create optional.
 - Vectors not converted to arrays when passed as raw vaargs. #2776
+- Second value in switch range not checked properly, causing an error on non-const values. #2777
 
 ### Fixes
 - Regression with npot vector in struct triggering an assert #2219.

src/compiler/sema_stmts.c

@@ -2432,10 +2432,10 @@ static inline bool sema_check_value_case(SemaContext *context, Type *switch_type
 		*if_chained = true;
 		return true;
 	}
-	if (is_range && !first_is_const)
+	if (is_range)
 	{
-		sema_error_at(context, extend_span_with_token(expr->span, to_expr->span), "Ranges must be constant integers.");
-		return false;
+		bool second_is_const = sema_cast_const(to_expr) && (expr_is_const_int(to_expr) || expr_is_const_enum(to_expr));
+		if (!first_is_const || !second_is_const) RETURN_SEMA_ERROR(first_is_const ? to_expr : expr, "Ranges must be constant integers or enum values, but this is not an integer / enum constant.");
 	}
 	bool is_enum = expr_is_const_enum(expr);
 	ExprConst *const_expr = &expr->const_expr;

test/test_suite/statements/ranged_switch_with_non_const_end.c3

@@ -0,0 +1,10 @@
+fn void main()
+{
+	for (int i = 0; ; )
+	{
+		switch (i)
+		{
+			case 4 .. i: // #error: Ranges must be constant integers or enum values, but this is not an integer
+		}
+	}
+}