Re: Git compile warnings (under mac/clang)

On Thu, Jan 22, 2015 at 10:20:01PM +0100, Johannes Schindelin wrote:

On 2015-01-22 20:59, Stefan Beller wrote:

quoted

cc Johannes Schindelin [off-list ref] who is working in
the fsck at the moment

On Thu, Jan 22, 2015 at 11:43 AM, Michael Blume [off-list ref] wrote:

quoted

    CC fsck.o
fsck.c:110:38: warning: comparison of unsigned enum expression >= 0 is
always true [-Wtautological-compare]
        if (options->msg_severity && msg_id >= 0 && msg_id < FSCK_MSG_MAX)
                                     ~~~~~~ ^  ~

According to A2.5.4 of The C Programming Language 2nd edition:

    Identifiers declared as enumerators (see Par.A.8.4) are constants of type int.

Therefore, the warning is incorrect: any assumption about enum fsck_msg_id to be unsigned is false.

I'm not sure that made it to ANSI. C99 says (setion 6.7.2.2, paragraph
4):

  Each enumerated type shall be compatible with char, a signed integer
  type, or an unsigned integer type. The choice of type is
  implementation-defined, but shall be capable of representing the
  values of all the members of the enumeration.

I don't have a copy of C89, but this isn't mentioned in the (very
cursory) list of changes found in C99. Anyway, that's academic.

I think we dealt with a similar situation before, in
3ce3ffb840a1dfa7fcbafa9309fab37478605d08.

-Peff