Re: [PATCHv2 8/9] checkout-index: Fix negations of even numbers of -n

On Wed, Jul 31, 2013 at 12:28 PM, Stefan Beller
[off-list ref] wrote:

The --no-create was parsed with OPT_BOOLEAN, which has a counting up
logic implemented. Since b04ba2bb (parse-options: deprecate OPT_BOOLEAN,
2011-09-27) the OPT_BOOLEAN is deprecated and is only a define:
        /* Deprecated synonym */
        #define OPTION_BOOLEAN OPTION_COUNTUP

However the variable not_new, which can be counted up by giving multiple
--no-create multiple times, is used to set a bit in the struct checkout

s/multiple --no-create multiple times/--no-create multiple times/

bitfield (defined in cache.h:969, declared at builtin/checkout-index.c:19):

        state.not_new = not_new;

When assigning a value other than 0 or 1 to a bit, all leading digits but
the last are ignored and only the last bit is used for setting the bit
variable.

Hence the following:
        # in git.git:
        $ git status
        # working directory clean
        rm COPYING
        $ git status
        # deleted:    COPYING
        $ git checkout-index -a -n
        # deleted:    COPYING
        # which is expected as we're telling git to not restore or create
        # files, however:
        $ git checkout-index -a -n -n
        $ git status
        # working directory clean, COPYING is restored again!
        # That's the bug, we're fixing here.

By restraining the variable not_new to a value being definitely 0 or 1
by the macro OPT_BOOL the bug is fixed.

Signed-off-by: Stefan Beller <redacted>