compiler: reword "declared and not used" error message

This is a gofrontend copy of

From the CL 203282 description:

    "declared and not used" is technically correct, but might confuse
    the user. Switching "and" to "but" will hopefully create the
    contrast for the users: they did one thing (declaration), but
    not the other --- actually using the variable.

Change-Id: Ie302171c3c6aa6d4429dc125cf994be8ad58554a
Trust: Ian Lance Taylor <>
Reviewed-by: Than McIntosh <>
2 files changed