← board

uses sysutils, pylib fails to compile; uses pylib, sysutils is fine

Pre-existing (reproduces on stable_linux_amd64/default/pinned). A two-line program is enough:

program t;
uses sysutils, pylib;      { swap the two and it compiles }
begin
  WriteLn(1);
end.



error: undefined variable (msg)
  near:  AnsiString   begin msg >>>  m

The failure is inside pylib's own Exception.Create, where msg := m no longer resolves msg to the class's field. pylib declares an Exception class and so does sysutils; with sysutils compiled first, pylib's constructor body binds against the wrong class and its field vanishes. Which unit is named first should not change whether a library compiles.

Related, and probably the same root: [[bug-nilpy-rtl-exception-surface-shadowed]] — pylib's Exception shadows sysutils', so Exception.CreateFmt is missing from NilPy. One of the two classes has to win properly, or they have to be one class (the "ONE Exception class" work in 873a693e did that for the NilPy side).

Where it bites

lib/pcl/mimic_reportlab_pdfgen.pas needs both (pylib for Python-shaped keyword arguments, sysutils for raise Exception.Create) and carries a comment pinning the order. Any library in the same position has to know this folklore.

Gate

make test + a regression test with both orders, and the pylib/sysutils Exception surfaces both reachable.

Log