[fpc-pascal] reference-counted function results not initialized to nil

[Michalis Kamburelis]

> After upgrading fpc 2.6.4 -> 3.0.0, I'm seeing a bug where (as noted in
> subject) reference-counted function results are not being initialized to
> nil.

They were never guaranteed to be initialized to nil.

Reference-counted types (unlike other types) cannot contain memory
garbage. But it doesn't mean that they are always initialized empty
when the function starts. You need to explicitly do Result := '' if
your code reads the Result later.

See similar questions for Delphi:
http://stackoverflow.com/questions/5336863/what-is-the-default-value-of-result-in-delphi
http://stackoverflow.com/questions/5314918/do-i-need-to-setlength-a-dynamic-array-on-initialization/5315254#5315254

Luckily, FPC warns about it, at least in my simple test:

$ fpc -vw a.lpr && ./a
a.lpr(5,20) Warning: function result variable of a managed type does
not seem to be initialized
blabla
blablablabla
blablablablablabla

Regards,
Michalis
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