r:            strings.NewReader("abcdefghijklmnopqrstuvwxyz"),
			n:            27,
			want:         26,
			wantErr:      io.EOF,
			wantBuffered: 0,
		},
		// Any error from filling shouldn't show up until we
		// get past the valid bytes. Here we return 5 valid bytes at the same time
		// as an error, but test that we don't see the error from Discard.
		{
			name: "fill error, discard less",

			result = true
		}

		// Add the second result type, if any.
		if twoResults {
			if name.FuncType.Result == nil {
				// An explicit void result looks odd but it
				// seems to be how cgo has worked historically.
				sb.WriteString("_Ctype_void")
			}
			sb.WriteString(", error)")
		}
	}

	sb.WriteString("{ ")

	// Define _cgoN for each argument value.