From da6760bdf5ed8ede203618d5118f4ceb2cb1652d Mon Sep 17 00:00:00 2001 From: Serhiy Storchaka Date: Mon, 4 Dec 2023 13:14:56 +0200 Subject: [PATCH] gh-65210: Add const qualifiers in PyArg_VaParseTupleAndKeywords() (GH-105958) Change the declaration of the keywords parameter in functions PyArg_ParseTupleAndKeywords() and PyArg_VaParseTupleAndKeywords() from `char **` to `char * const *` in C and `const char * const *` in C++. It makes these functions compatible with argument of type `const char * const *`, `const char **` or `char * const *` in C++ and `char * const *` in C without explicit type cast. Co-authored-by: C.A.M. Gerlach --- Doc/c-api/arg.rst | 26 +++++++++++++++++-- Doc/extending/extending.rst | 2 +- Doc/whatsnew/3.13.rst | 10 +++++++ Include/modsupport.h | 4 +-- Include/pyport.h | 8 ++++++ ...3-06-21-11-53-09.gh-issue-65210.PhFRBJ.rst | 3 +++ Python/getargs.c | 17 ++++++------ 7 files changed, 57 insertions(+), 13 deletions(-) create mode 100644 Misc/NEWS.d/next/C API/2023-06-21-11-53-09.gh-issue-65210.PhFRBJ.rst diff --git a/Doc/c-api/arg.rst b/Doc/c-api/arg.rst index 62d87d898e6..834aae9372f 100644 --- a/Doc/c-api/arg.rst +++ b/Doc/c-api/arg.rst @@ -413,7 +413,7 @@ API Functions than a variable number of arguments. -.. c:function:: int PyArg_ParseTupleAndKeywords(PyObject *args, PyObject *kw, const char *format, char *keywords[], ...) +.. c:function:: int PyArg_ParseTupleAndKeywords(PyObject *args, PyObject *kw, const char *format, char * const *keywords, ...) Parse the parameters of a function that takes both positional and keyword parameters into local variables. @@ -424,15 +424,24 @@ API Functions Returns true on success; on failure, it returns false and raises the appropriate exception. + .. note:: + + The *keywords* parameter declaration is :c:expr:`char * const *` in C and + :c:expr:`const char * const *` in C++. + This can be overridden with the :c:macro:`PY_CXX_CONST` macro. + .. versionchanged:: 3.6 Added support for :ref:`positional-only parameters `. .. versionchanged:: 3.13 + The *keywords* parameter has now type :c:expr:`char * const *` in C and + :c:expr:`const char * const *` in C++, instead of :c:expr:`char **`. Added support for non-ASCII keyword parameter names. -.. c:function:: int PyArg_VaParseTupleAndKeywords(PyObject *args, PyObject *kw, const char *format, char *keywords[], va_list vargs) + +.. c:function:: int PyArg_VaParseTupleAndKeywords(PyObject *args, PyObject *kw, const char *format, char * const *keywords, va_list vargs) Identical to :c:func:`PyArg_ParseTupleAndKeywords`, except that it accepts a va_list rather than a variable number of arguments. @@ -505,6 +514,19 @@ API Functions PyArg_ParseTuple(args, "O|O:ref", &object, &callback) +.. c:macro:: PY_CXX_CONST + + The value to be inserted, if any, before :c:expr:`char * const *` + in the *keywords* parameter declaration of + :c:func:`PyArg_ParseTupleAndKeywords` and + :c:func:`PyArg_VaParseTupleAndKeywords`. + Default empty for C and ``const`` for C++ + (:c:expr:`const char * const *`). + To override, define it to the desired value before including + :file:`Python.h`. + + .. versionadded:: 3.13 + --------------- Building values diff --git a/Doc/extending/extending.rst b/Doc/extending/extending.rst index 1ee7f28b2ba..745fc10a22d 100644 --- a/Doc/extending/extending.rst +++ b/Doc/extending/extending.rst @@ -735,7 +735,7 @@ Keyword Parameters for Extension Functions The :c:func:`PyArg_ParseTupleAndKeywords` function is declared as follows:: int PyArg_ParseTupleAndKeywords(PyObject *arg, PyObject *kwdict, - const char *format, char *kwlist[], ...); + const char *format, char * const *kwlist, ...); The *arg* and *format* parameters are identical to those of the :c:func:`PyArg_ParseTuple` function. The *kwdict* parameter is the dictionary of diff --git a/Doc/whatsnew/3.13.rst b/Doc/whatsnew/3.13.rst index 676305c6e1d..be890ff314d 100644 --- a/Doc/whatsnew/3.13.rst +++ b/Doc/whatsnew/3.13.rst @@ -1111,6 +1111,16 @@ New Features APIs accepting the format codes always use ``Py_ssize_t`` for ``#`` formats. (Contributed by Inada Naoki in :gh:`104922`.) +* The *keywords* parameter of :c:func:`PyArg_ParseTupleAndKeywords` and + :c:func:`PyArg_VaParseTupleAndKeywords` has now type :c:expr:`char * const *` + in C and :c:expr:`const char * const *` in C++, instead of :c:expr:`char **`. + It makes these functions compatible with arguments of type + :c:expr:`const char * const *`, :c:expr:`const char **` or + :c:expr:`char * const *` in C++ and :c:expr:`char * const *` in C + without an explicit type cast. + This can be overridden with the :c:macro:`PY_CXX_CONST` macro. + (Contributed by Serhiy Storchaka in :gh:`65210`.) + * Add :c:func:`PyImport_AddModuleRef`: similar to :c:func:`PyImport_AddModule`, but return a :term:`strong reference` instead of a :term:`borrowed reference`. diff --git a/Include/modsupport.h b/Include/modsupport.h index 450cc99c404..ea4c0fce9f4 100644 --- a/Include/modsupport.h +++ b/Include/modsupport.h @@ -9,10 +9,10 @@ extern "C" { PyAPI_FUNC(int) PyArg_Parse(PyObject *, const char *, ...); PyAPI_FUNC(int) PyArg_ParseTuple(PyObject *, const char *, ...); PyAPI_FUNC(int) PyArg_ParseTupleAndKeywords(PyObject *, PyObject *, - const char *, char **, ...); + const char *, PY_CXX_CONST char * const *, ...); PyAPI_FUNC(int) PyArg_VaParse(PyObject *, const char *, va_list); PyAPI_FUNC(int) PyArg_VaParseTupleAndKeywords(PyObject *, PyObject *, - const char *, char **, va_list); + const char *, PY_CXX_CONST char * const *, va_list); PyAPI_FUNC(int) PyArg_ValidateKeywordArguments(PyObject *); PyAPI_FUNC(int) PyArg_UnpackTuple(PyObject *, const char *, Py_ssize_t, Py_ssize_t, ...); diff --git a/Include/pyport.h b/Include/pyport.h index abb526d503f..328471085f9 100644 --- a/Include/pyport.h +++ b/Include/pyport.h @@ -586,6 +586,14 @@ extern "C" { # define ALIGNOF_MAX_ALIGN_T _Alignof(long double) #endif +#ifndef PY_CXX_CONST +# ifdef __cplusplus +# define PY_CXX_CONST const +# else +# define PY_CXX_CONST +# endif +#endif + #if defined(__sgi) && !defined(_SGI_MP_SOURCE) # define _SGI_MP_SOURCE #endif diff --git a/Misc/NEWS.d/next/C API/2023-06-21-11-53-09.gh-issue-65210.PhFRBJ.rst b/Misc/NEWS.d/next/C API/2023-06-21-11-53-09.gh-issue-65210.PhFRBJ.rst new file mode 100644 index 00000000000..a15646f4dad --- /dev/null +++ b/Misc/NEWS.d/next/C API/2023-06-21-11-53-09.gh-issue-65210.PhFRBJ.rst @@ -0,0 +1,3 @@ +Change the declaration of the *keywords* parameter of +:c:func:`PyArg_ParseTupleAndKeywords` and +:c:func:`PyArg_VaParseTupleAndKeywords` for better compatibility with C++. diff --git a/Python/getargs.c b/Python/getargs.c index 5ff8f747360..0c4ce282f48 100644 --- a/Python/getargs.c +++ b/Python/getargs.c @@ -1,6 +1,7 @@ /* New getargs implementation */ +#define PY_CXX_CONST const #include "Python.h" #include "pycore_abstract.h" // _PyNumber_Index() #include "pycore_dict.h" // _PyDict_HasOnlyStringKeys() @@ -12,10 +13,10 @@ PyAPI_FUNC(int) _PyArg_Parse_SizeT(PyObject *, const char *, ...); PyAPI_FUNC(int) _PyArg_ParseTuple_SizeT(PyObject *, const char *, ...); PyAPI_FUNC(int) _PyArg_ParseTupleAndKeywords_SizeT(PyObject *, PyObject *, - const char *, char **, ...); + const char *, const char * const *, ...); PyAPI_FUNC(int) _PyArg_VaParse_SizeT(PyObject *, const char *, va_list); PyAPI_FUNC(int) _PyArg_VaParseTupleAndKeywords_SizeT(PyObject *, PyObject *, - const char *, char **, va_list); + const char *, const char * const *, va_list); #define FLAG_COMPAT 1 @@ -54,7 +55,7 @@ static Py_ssize_t convertbuffer(PyObject *, const void **p, const char **); static int getbuffer(PyObject *, Py_buffer *, const char**); static int vgetargskeywords(PyObject *, PyObject *, - const char *, char **, va_list *, int); + const char *, const char * const *, va_list *, int); static int vgetargskeywordsfast(PyObject *, PyObject *, struct _PyArg_Parser *, va_list *, int); static int vgetargskeywordsfast_impl(PyObject *const *args, Py_ssize_t nargs, @@ -1247,7 +1248,7 @@ int PyArg_ParseTupleAndKeywords(PyObject *args, PyObject *keywords, const char *format, - char **kwlist, ...) + const char * const *kwlist, ...) { int retval; va_list va; @@ -1271,7 +1272,7 @@ int _PyArg_ParseTupleAndKeywords_SizeT(PyObject *args, PyObject *keywords, const char *format, - char **kwlist, ...) + const char * const *kwlist, ...) { int retval; va_list va; @@ -1297,7 +1298,7 @@ int PyArg_VaParseTupleAndKeywords(PyObject *args, PyObject *keywords, const char *format, - char **kwlist, va_list va) + const char * const *kwlist, va_list va) { int retval; va_list lva; @@ -1322,7 +1323,7 @@ int _PyArg_VaParseTupleAndKeywords_SizeT(PyObject *args, PyObject *keywords, const char *format, - char **kwlist, va_list va) + const char * const *kwlist, va_list va) { int retval; va_list lva; @@ -1460,7 +1461,7 @@ PyArg_ValidateKeywordArguments(PyObject *kwargs) static int vgetargskeywords(PyObject *args, PyObject *kwargs, const char *format, - char **kwlist, va_list *p_va, int flags) + const char * const *kwlist, va_list *p_va, int flags) { char msgbuf[512]; int levels[32];