gh-140001: Remove obsolete TCL_WIN_SOCKET macro (from Tcl 7.x) from _tkinter.c

[mdehoon]

The macro TCL_WIN_SOCKET used in Modules/_tkinter.c is a Tcl 7.x legacy macro that is no longer defined in Tcl ≥ 8.0.
As Python now requires Tcl 8.5.12, the code path is now unreachable, and can safely be removed.

The macro FHANDLETYPE defined in Modules/_tkinter.c then always evaluates to TCL_UNIX_FD, and can also be removed.

• Issue: Modules/_tkinter.c uses legacy macros TCL_WIN_SOCKET, TCL_UNIX_FD from Tcl 7.x #140001

[picnixz]

Please open an issue and link the Tcl documentation as well; TiA.

[mdehoon]

See https://www.tcl-lang.org/man/tcl7.6/TclLib/GetFile.3.html for a description of these macros in Tcl 7.6.
The macros TCL_WIN_SOCKET and TCL_UNIX_FD were used in Tcl_GetFile, which was removed in Tcl 8.0.

See generic/tcl.h in the Tcl 7.6 source code for the definition of these two macros:

#define TCL_UNIX_FD	1
#define TCL_WIN_SOCKET	6

These macros are not defined in generic/tcl.h of Tcl 8.0, or mentioned anywhere else in the Tcl 8.0 source code.

[serhiy-storchaka]

Should not WAIT_FOR_STDIN be removed too?

[mdehoon]

WAIT_FOR_STDIN is not always defined: it remains undefined if __CYGWIN__ is defined.

[serhiy-storchaka]

LGTM. 👍