On 04/27/2011 10:29 AM, Tom Lane wrote:
Andrew Dunstan<and...@dunslane.net> writes:
On 04/27/2011 12:50 AM, Tom Lane wrote:
Andrew Dunstan<and...@dunslane.net> writes:
All or almost all the warnings seen on Windows/Mingw of the type
"warning: unknown conversion type character 'm' in format" come from
checking of three functions: errmsg, elog and errdetail. I therefore
propose to disable the attribute checking of those three functions, on
Windows only (since that's the only place I've seen the warnings).
That seems to me to be throwing the baby out with the bathwater.
If Windows could be assumed to be just like every other platform,
we could maybe figure that being format-warning-free elsewhere
was sufficient checking; but that assumption is obviously wrong.
We're not doing anything about the warnings, and I'm not sure there's
anything we can do other than suppress them or live with them.
The compiler is in fact quite correct, it doesn't know anything about
"%m", and if we were ever to use %m in a context where we actually
expected it to output the contents of strerror(errno) the warning would
be lost among a huge pile of these other warnings where its use is
harmless because we expand it ourselves. That strikes me as a more
potent danger.
I don't buy that. The risk that gcc will let past a '%m' without
complaint, in a function that doesn't actually support it, exists on
most non-Linux platforms (ie pretty much anywhere you use gcc with
non-GNU libc), and has existed from the beginning. Despite this,
I cannot recall that we have ever had a bug of that ilk. But we have
most certainly had bugs with incorrect/unportable matching of other
format arguments. I think losing the ability to detect the latter
in Windows-specific code is a terrible price to pay for silencing
an easily-ignorable class of warnings.
What I'd like to know is why it doesn't complain elsewhere. The one
non-Linux non-Windows machine I have is FBSD. Its gcc (4.2.1) doesn't
expand "%m" but doesn't complain about it either. It does complain
about other unknown formats. I wonder if they have patched gcc to
silence the warnings?
cheers
andrew
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