On Wed, Mar 20, 2019 at 02:54:22PM +0000, Daniel P. Berrangé wrote: > On Wed, Mar 20, 2019 at 01:52:26PM +0000, Stefan Hajnoczi wrote: > > On Fri, Mar 15, 2019 at 03:51:15PM +0100, Markus Armbruster wrote: > > > * Our use of header guards is rather sloppy. Sloppiness there can > > > lead to confusing compilation errors. The rest of the series cleans > > > up existing header guards. In particular, it normalizes guard > > > symbols to follow a common pattern, in the hope of making clashes > > > less likely. It doesn't add new header guards. We have more than > > > 200 headers without a recognizable header guard. A few of them are > > > for multiple inclusion, a few more don't need header guards because > > > they don't do anything but include, but the majority probably should > > > have one. Left for another day. > > > > Time for #pragma once? > > https://en.wikipedia.org/wiki/Pragma_once > > That seems like a reasonable idea to me. We already mandate CLang or > GCC as only supported compilers, so there's no portability concerns. > > > On the subject of non-standard C extensions, I was also wondering if > QEMU should consider use of __attribute__((cleanup($func))) for doing > automatically free'ing of memory when variables go out of scope. As > well as reducing possibility of memory leaks, this simplifies code > as it often allows for many "goto cleanup" jumps to be replaced with > direct "return -1"s. It isn't the most attractive syntax, but that > downside doesn't outweigh the positives from my POV. > > We recently started using it in libvirt for this reason. > > Glib2 itself already uses this since 2.44 and exposes some macros for > client code to use for this. > > We bumped min glib to 2.40 a year go because Debian Jessie has 2.42 > and Ubuntu Trusty needs 2.40 which Peter used as a build merge test > machine. > > Our platform support policy will let us drop Jessie support when > Buster is released fairly soon. If Peter no longer uses Trusty > machines for buld, we'll soon be able to have a min glib that uses > attribute(cleanup) as a standard dep.
That sounds good to me. I've also seen __attribute__((cleanup($func))) used more frequently in other projects and it makes the code both simpler and safer. Stefan
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