bug in PLPGSQL

Your name : Andriy I Pilipenko
Your email address : bamby(at)marka(dot)net(dot)ua

System Configuration
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Architecture (example: Intel Pentium) : Intel Pentium

Operating System (example: Linux 2.0.26 ELF) : FreeBSD-4.2-STABLE

PostgreSQL version (example: PostgreSQL-7.0): PostgreSQL-7.0.3

Compiler used (example: gcc 2.8.0) : gcc version 2.95.2 19991024 (release)

Please enter a FULL description of your problem:
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There is bug in PLPGSQL. If one of the parameters to plpgsql function is
null, other parameters becomes null too.

Please describe a way to repeat the problem. Please try to provide a
concise reproducible example, if at all possible:
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First create function like this:

CREATE FUNCTION f(varchar, varchar) RETURNS varchar
AS '
begin
return ''first arg is: '' || $1;
end;
' LANGUAGE 'plpgsql';

Then run query "SELECT f('some text', NULL)" and you will receive null
value.

If you know how this problem might be fixed, list the solution below:
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