COMP: Resolve DCMTK/Python macro redefs in AUTOGEN mocs TU; prevent Windows pid_t clash

[jcfr]

AUTOMOC merges all moc_*.cpp into one Translation Unit (TU) (<target>_autogen/mocs_compilation*.cpp). For CTKDICOMWidgets, that TU ends up including both Python.h (via PythonQt) and DCMTK's osconfig.h. Across platforms, pyconfig.h and osconfig.h define overlapping HAVE_* feature macros; when merged, this yields widespread redefinition warnings.

On Windows, pyconfig.h may also typedef pid_t, colliding with DCMTK’s typedef and causing MSVC C2632 ("int followed by int is illegal"). On Unix-like systems, pid_t comes from <sys/types.h>, so the type clash does not escalate.

Fix:

• Include PythonQtPythonInclude.h first in the generated wrapper header.
• Immediately #undef a minimal set of Python-defined HAVE_* macros so DCMTK can (re)define them without conflict, restoring the effective isolation we had before enabling AUTOMOC.

Behavior is unchanged; this quiets warnings cross-platform and prevents the Windows build error.

[jcfr]

This addresses the build error and warnings reported last night on CDash¹

Error:

(compiling source file 'CTKDICOMWidgetsPythonQt_autogen/mocs_compilation_Release.cpp')
    C:\path\to\Slicer-build\DCMTK-build\config\include\dcmtk\config\osconfig.h(1083,9):
    see previous definition of 'HAVE_STRERROR'
C:\path\to\Slicer-build\python-install\include\pyconfig.h(225,13): error C2632: 'int' followed by 'int' is illegal

Warnings:

C:\path\to\Slicer-build\python-install\include\pyconfig.h(51,9): warning C4005: 'HAVE_IO_H': macro redefinition
(compiling source file 'CTKDICOMWidgetsPythonQt_autogen/mocs_compilation_Release.cpp')
    C:\path\to\Slicer-build\DCMTK-build\config\include\dcmtk\config\osconfig.h(179,9):
    see previous definition of 'HAVE_IO_H'
C:\path\to\Slicer-build\python-install\include\pyconfig.h(52,9): warning C4005: 'HAVE_SYS_UTIME_H': macro redefinition
(compiling source file 'CTKDICOMWidgetsPythonQt_autogen/mocs_compilation_Release.cpp')
    C:\path\to\Slicer-build\DCMTK-build\config\include\dcmtk\config\osconfig.h(446,9):
    see previous definition of 'HAVE_SYS_UTIME_H'
C:\path\to\Slicer-build\python-install\include\pyconfig.h(53,9): warning C4005: 'HAVE_TEMPNAM': macro redefinition
(compiling source file 'CTKDICOMWidgetsPythonQt_autogen/mocs_compilation_Release.cpp')
    C:\path\to\Slicer-build\DCMTK-build\config\include\dcmtk\config\osconfig.h(1088,9):
    see previous definition of 'HAVE_TEMPNAM'
C:\path\to\Slicer-build\python-install\include\pyconfig.h(55,9): warning C4005: 'HAVE_TMPNAM': macro redefinition
(compiling source file 'CTKDICOMWidgetsPythonQt_autogen/mocs_compilation_Release.cpp')
    C:\path\to\Slicer-build\DCMTK-build\config\include\dcmtk\config\osconfig.h(1090,9):
    see previous definition of 'HAVE_TMPNAM'
C:\path\to\Slicer-build\python-install\include\pyconfig.h(57,9): warning C4005: 'HAVE_STRERROR': macro redefinition
(compiling source file 'CTKDICOMWidgetsPythonQt_autogen/mocs_compilation_Release.cpp')
C:\path\to\Slicer-build\python-install\include\pyconfig.h(524,9): warning C4005: 'HAVE_FTIME': macro redefinition
(compiling source file 'CTKDICOMWidgetsPythonQt_autogen/mocs_compilation_Release.cpp')
    C:\path\to\Slicer-build\DCMTK-build\config\include\dcmtk\config\osconfig.h(114,9):
    see previous definition of 'HAVE_FTIME'
C:\path\to\Slicer-build\python-install\include\pyconfig.h(533,9): warning C4005: 'HAVE_GETPID': macro redefinition
(compiling source file 'CTKDICOMWidgetsPythonQt_autogen/mocs_compilation_Release.cpp')
    C:\path\to\Slicer-build\DCMTK-build\config\include\dcmtk\config\osconfig.h(144,9):
    see previous definition of 'HAVE_GETPID'

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Since similar workaround have been implemented in other location in both CTK and Slicer, consolidation of those will be required and is tracked in those issues:

• Robust fix needed: DCMTK ↔ Python HAVE_* macro/type collisions when AUTOMOC merges moc TUs Slicer/Slicer#8822
• Robust fix needed: DCMTK ↔ Python HAVE_* macro/type collisions when AUTOMOC merges moc TUs #1274

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cc: @jamesobutler @ebrahimebrahim

Footnotes

1. https://slicer.cdash.org/builds/3984970 ↩