Re: Compile error

Hi Albrecht!

On 03/14/2022 04:56:42 PM Mon, Albrecht Dreß via balsa-list wrote:
Hi Andreas,

thanks a lot for your report!

Am 14.03.22 13:52 schrieb(en) AS via balsa-list:
        mailbox_imap.c: In function ‘libbalsa_mailbox_imap_fetch_headers’:
        mailbox_imap.c:2333:15: error: comparison of integer expressions of different signedness: ‘glong’ 
{aka ‘long int’} and ‘unsigned int’ [-Werror=sign-compare]
         2333 |     if (msgno > imap_mbox_handle_get_exists(mimap->handle))
                        |               ^
        cc1: all warnings being treated as errors

Yes, that's a bug in the code!  Which probably slipped through with older compilers than on Debian unstable…

I'm not really familiar with the IMAP code, but I *think* the trivial solution would be to declare msgno as 
unsigned in line 2328, and to add a cast to unsigned in line 2330, as all the imap_* functions use unsigned 
as parameters.  Peter?


Yes, that should fix it!

But I'm left with a few questions:
•  First, why didn't I get that warning/error when I committed that test a year ago? Meson sets "-Wall", which implies 
"-Wsign-compare", and even including "-Wsign-compare" explicitly doesn't result in the warning!
•  Also, why does Balsa use a signed type for message numbers? They are 1-based, and zero is already used as 
the invalid value, so all negative values are presumably unused.
•  And "glong" (aka "long int", or "long") seems extravagant; it's presumably left over from when 16-bit ints were 
common but a mailbox with more than 32,767 messages was possible; surely "unsigned" would be adequate today.


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