[freitasjca]

Summary

THorseWebSocketSocketTransport.WaitReadable fails to compile on Delphi-Linux64 (any Delphi POSIX target): E2029 in its Delphi-POSIX branch. The WebSocket transport is therefore unbuildable on Delphi-Linux64.

Root cause

In the Delphi, non-Windows ({$ELSE}) branch of WaitReadable (src/Horse.Provider.Socket.WebSocket.pas, ~line 299):

FD_ZERO(LSet);
FD_SET(ASocket, LSet);            // E2029 here
...
select(ASocket + 1, @LSet, nil, nil, @LTimeout)

On Delphi-POSIX, FD_SET is (case-insensitively) the type fd_set, not a macro — so FD_SET(ASocket, LSet) parses as a typecast and the compiler reports E2029 ')' expected but ',' found. The POSIX fd_set helpers are spelled __FD_ZERO / __FD_SET, and select needs Posix.SysSelect qualification to disambiguate.

This branch had not been compiled before: the WebSocket CI (PR #549) built FPC-Linux + Delphi-Windows only, and the Delphi-POSIX {$ELSE} is reached only on a Delphi POSIX target. It surfaced building the Epoll sample for Delphi-Linux64.

Fix

__FD_ZERO(LSet);
__FD_SET(ASocket, LSet);
...
Result := Posix.SysSelect.select(ASocket + 1, @LSet, nil, nil, @LTimeout) > 0;

This matches Delphi's own Indy POSIX stack (IdStackVCLPosix uses __FD_SET). The change is isolated to the Delphi-POSIX branch — the FPC branch (fpFD_* / fpSelect) and the Delphi-Windows branch (Winsock FD_SET) are untouched.

On testing — an honest note

This is a compile-time fix, and a functional/unit test cannot guard it: the WebSocket integration tests run on Windows and FPC-Linux, where the pre-fix code already compiled — the defect is reachable only when the unit is compiled for a Delphi POSIX target, so a runtime test would pass identically on broken and fixed code.

The appropriate regression guard is a CI job that compiles the WebSocket transport for Delphi-Linux64. If that target isn't in the current matrix, I'm happy to add a compile-only job in a follow-up — it's the only thing that would have caught this, and it would catch the same class of Delphi-POSIX issue elsewhere.

Files

• src/Horse.Provider.Socket.WebSocket.pas — Delphi-POSIX branch of WaitReadable.