Re: Is this non-volatile pointer access OK?

On Mon, 2012-09-03 at 11:14 +0100, Peter Geoghegan wrote:
> Come to think of it, the whole convention of using a lower-case
> variant of the original pointer variable name seems like a foot-gun,
> given the harmful and indeed very subtle consequences of making this
> error.

With some inventive macro magic, you could probably make this safer.
I'm thinking something along the lines of replacing

SpinLockAcquire(&xlogctl->info_lck);

with

SpinLockAcquire(XLogCtl, info_lck);

which expands to

{
    volatile typeof(XLogCtl) *XLogCtl_volatile = XLogCtl;
    void *XLogCtl = NULL;  // compiler error or crash at run time if used
    OldSpinLockAcquire(XLogCtl_volatile->info_lock);
    ...

and then something corresponding for SpinLockRelease.

This will likely only work with modern compilers, but it could give you
some amount of static checking against this problem.