Horton

Re: Nicely exiting PG_TRY and PG_CATCH

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Mikhail Gribkov <youzhick@gmail.com>
Cc: pgsql-hackers@lists.postgresql.org
Date: 2022-10-07T21:19:03Z
Lists: pgsql-hackers 
Mikhail Gribkov <youzhick@gmail.com> writes:
> Usually it's not a good idea to exit PG_TRY() block via return statement.
> Otherwise it would leave PG_exception_stack global variable in a wrong
> state and next ereport() will jump to some junk address.

Yeah, you can't return or goto out of the PG_TRY part.

> Another suspicious case is PG_CATCH block in jsonb_plpython.c:

This should be OK.  The PG_CATCH and PG_FINALLY macros are set up so that
we've fully restored that state *before* we execute any of the
error-handling code.  It would be basically impossible to have a guarantee
that CATCH blocks never throw errors; they'd be so restricted as to be
near useless, like signal handlers.

			regards, tom lane

Commits

  1. Move return statements out of PG_TRY blocks.

  2. Add -Wshadow=compatible-local to the standard compilation flags