[fpc-pascal] Unable to compile fpc 3.0.4

[Giuliano Colla]

I've stumbled into a problem.

On one platform (linux x86_64, distro is CentOs6) I'm unable to compile 
fpc packages of fpc 3.0.4

The compiler is successful but the package compilation fails on package 
paszlib. The error given is

zbase.pas(446,7) Error: Illegal expression
zbase.pas(447,36) Error: Operator is not overloaded: "Constant String" + 
"zError(LongInt):AnsiString;"
zbase.pas(506) Fatal: There were 2 errors compiling module, stopping
Fatal: Compilation aborted

The affected lines are:

       str(err,zerror);
       zerror:='Unknown zlib error '+zerror;

if I patch those lines, sort of:

       //str(err,zerror);
       zerror:='Unknown zlib error ';//+zerror;

then compilation fails in trees.pas: all occurences of tree[n].xx give 
raise to an error

trees.pas(871,18) Error: Array type required

(followed by 30 more similar messages)

I have no clue of where could be the problem.

Any hint will be greatly appreciated.

Giuliano