Re: proposal: plpgsql, new check for extra_errors - strict_expr_check

Hi

I rewrote this patch. Instead of enhancing the main SQL parser, it does
post parser checks of the parse tree.

Now the patch is significantly less invasive (changes are just in plpgsql -
mostly in grammar), and it is smaller (without regress tests it has half
size).

This patch allows the detection of usage of undocumented syntax for plpgsql
expressions. Using this undocumented
syntax can be the reason why badly written code (missing semicolon) can be
quietly executed without any raising of error.

Only patch 01 is important - patches 02, 03 are prepared for review.
Patch 02 activates a new check by default, and fixes the regress test to be
executed. This is important for checking for possible false alarms.
Patch 03 disables this check and returns regress tests to their original
state.

Regards

Pavel