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

Michalis Kamburelis michalis.kambi at gmail.com
Sat Jun 25 05:19:42 CEST 2016

> 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:

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

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