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Implement Py_UNUSED() for Windows MSVC compiler #107249

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vstinner opened this issue Jul 25, 2023 · 0 comments
Closed

Implement Py_UNUSED() for Windows MSVC compiler #107249

vstinner opened this issue Jul 25, 2023 · 0 comments
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type-feature A feature request or enhancement

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vstinner commented Jul 25, 2023 •
edited by bedevere-app bot
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The Py_UNUSED() is not implemented for the Windows MSVC compiler.

Example with this function included by Python.h: see #107239 (comment)

static inline unsigned int
PyUnicode_IS_READY(PyObject* Py_UNUSED(op))
{ return 1; }

Without my change, building a C program with cl /W4 which just includes Python.h emits the warning:

Include\cpython/unicodeobject.h(199): warning C4100: '_unused_op': unreferenced formal parameter

With my change, no warnings are emitted!

Linked PRs
@vstinner vstinner added the type-feature A feature request or enhancement label Jul 25, 2023
vstinner added a commit to vstinner/cpython that referenced this issue Jul 25, 2023
@vstinner
pythongh-107249: Implement Py_UNUSED() for MSVC
b9cc3b6 
Fix warnings C4100 in Py_UNUSED() when Python is built with "cl /W4".

Example with this function included by Python.h:

    static inline unsigned int
    PyUnicode_IS_READY(PyObject* Py_UNUSED(op))
    { return 1; }

Without this change, building a C program with "cl /W4" which just
includes Python.h emits the warning:

    Include\cpython/unicodeobject.h(199):
    warning C4100: '_unused_op': unreferenced formal parameter

This change fix this warning.
@bedevere-bot bedevere-bot mentioned this issue Jul 25, 2023
Merged
vstinner added a commit that referenced this issue Jul 25, 2023
@vstinner
gh-107249: Implement Py_UNUSED() for MSVC (#107250)
6a43cce 
Fix warnings C4100 in Py_UNUSED() when Python is built with "cl /W4".

Example with this function included by Python.h:

    static inline unsigned int
    PyUnicode_IS_READY(PyObject* Py_UNUSED(op))
    { return 1; }

Without this change, building a C program with "cl /W4" which just
includes Python.h emits the warning:

    Include\cpython/unicodeobject.h(199):
    warning C4100: '_unused_op': unreferenced formal parameter

This change fix this warning.
jtcave pushed a commit to jtcave/cpython that referenced this issue Jul 27, 2023
@vstinner @jtcave
pythongh-107249: Implement Py_UNUSED() for MSVC (python#107250)
f7f712e 
Fix warnings C4100 in Py_UNUSED() when Python is built with "cl /W4".

Example with this function included by Python.h:

    static inline unsigned int
    PyUnicode_IS_READY(PyObject* Py_UNUSED(op))
    { return 1; }

Without this change, building a C program with "cl /W4" which just
includes Python.h emits the warning:

    Include\cpython/unicodeobject.h(199):
    warning C4100: '_unused_op': unreferenced formal parameter

This change fix this warning.
bdegreve added a commit to cocamware/lass that referenced this issue Aug 15, 2024
@bdegreve
Suppress unreferenced '_unused_op' warning
406ed45 
On Windows, with cl /W4, we get following warning with Python 3.12:

  C:\Program Files\Python312\include\cpython/unicodeobject.h(203,57): warning C4100: '_unused_op': unreferenced formal parameter

Py_UNUSED hasn't changed in 5 years [1], but in Python 3.12 it started
being used in unicodeobject.h [2] so it became part of the public
interface. Because Py_UNUSED only prepended _unused_ to the parameter
name for MSVC [1], we get the C4100 warning when compiling with /W4.
In Python 3.13 this got fixed by adding a specific implementation of
Py_UNUSED for MSVC [3], so the warning is unique to Python 3.12.
However, as we don't know PY_VERSION_HEX _before_ including Python.h,
we'll indiscriminately suppress the C4100 while including Python.h.

[1] https://github.com/python/cpython/blame/3.12/Include/pymacro.h#L114-L123
[2] python/cpython@b2694ab
[3] python/cpython#107249
miss-islington pushed a commit to miss-islington/cpython that referenced this issue Dec 13, 2024
@vstinner @miss-islington
pythongh-107249: Implement Py_UNUSED() for MSVC (pythonGH-107250)
3e904d1 
Fix warnings C4100 in Py_UNUSED() when Python is built with "cl /W4".

Example with this function included by Python.h:

    static inline unsigned int
    PyUnicode_IS_READY(PyObject* Py_UNUSED(op))
    { return 1; }

Without this change, building a C program with "cl /W4" which just
includes Python.h emits the warning:

    Include\cpython/unicodeobject.h(199):
    warning C4100: '_unused_op': unreferenced formal parameter

This change fix this warning.
(cherry picked from commit 6a43cce)

Co-authored-by: Victor Stinner <[email protected]>
@bedevere-app bedevere-app bot mentioned this issue Dec 13, 2024
Merged
vstinner added a commit that referenced this issue Dec 13, 2024
@miss-islington @vstinner
[3.12] gh-107249: Implement Py_UNUSED() for MSVC (GH-107250) (#127907)
f3a689f 
gh-107249: Implement Py_UNUSED() for MSVC (GH-107250)

Fix warnings C4100 in Py_UNUSED() when Python is built with "cl /W4".

Example with this function included by Python.h:

    static inline unsigned int
    PyUnicode_IS_READY(PyObject* Py_UNUSED(op))
    { return 1; }

Without this change, building a C program with "cl /W4" which just
includes Python.h emits the warning:

    Include\cpython/unicodeobject.h(199):
    warning C4100: '_unused_op': unreferenced formal parameter

This change fix this warning.
(cherry picked from commit 6a43cce)

Co-authored-by: Victor Stinner <[email protected]>
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