stage2: add test for fixed issue

Author: Vexu

test/behavior.zig

@@ -81,6 +81,7 @@ test {
     _ = @import("behavior/bugs/11159.zig");
     _ = @import("behavior/bugs/11162.zig");
     _ = @import("behavior/bugs/11165.zig");
+    _ = @import("behavior/bugs/11179.zig");
     _ = @import("behavior/bugs/11181.zig");
     _ = @import("behavior/bugs/11182.zig");
     _ = @import("behavior/bugs/11213.zig");

test/behavior/bugs/11179.zig

@@ -0,0 +1,18 @@
+const std = @import("std");
+const Type = std.builtin.Type;
+
+test "Tuple" {
+    const fields_list = fields(@TypeOf(.{}));
+    if (fields_list.len != 0)
+        @compileError("Argument count mismatch");
+}
+
+pub fn fields(comptime T: type) switch (@typeInfo(T)) {
+    .Struct => []const Type.StructField,
+    else => unreachable,
+} {
+    return switch (@typeInfo(T)) {
+        .Struct => |info| info.fields,
+        else => unreachable,
+    };
+}