Re: [HACKERS] Odd behavior with PG_TRY

Kevin Grittner <kgrittn@gmail.com> writes:
> On Fri, Jan 6, 2017 at 5:43 AM, Michael Paquier
> <michael.paquier@gmail.com> wrote:
>> If a variable is modified within PG_TRY and then referenced in
>> PG_CATCH it needs to be marked as volatile to be strictly in
>> conformance with POSIX. This also ensures that any compiler does not
>> do any stupid optimizations with those variables in the way they are
>> referenced and used.

> That sort of begs the question of why PG_exception_stack is not
> marked as volatile, since the macros themselves modify it within
> the PG_TRY block and reference it within the PG_CATCH block.  Is
> there some reason this variable is immune to the problem?

It's not a local variable.
        regards, tom lane