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",

				directive := fields[1]
				funcName := fields[2]
				if directive == "nocallback" {
					fatalf("#cgo nocallback disabled until Go 1.23")
					f.NoCallbacks[funcName] = true
				} else if directive == "noescape" {
					fatalf("#cgo noescape disabled until Go 1.23")
					f.NoEscapes[funcName] = true
				}
			}
		}
	}
	f.Preamble = strings.Join(linesOut, "\n")
}