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-Wwrite-strings: Add a PyArg_ParseTupleAndKeywords "const char *" overload

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-Wwrite-strings flags code like:

   static char *keywords[] = {"command", "from_tty", "to_string", NULL };

as needing "(char *)" casts, because string literals are "const char []".

We can get rid of the casts by changing the array type like this:

 -  static char *keywords[] = {"command", "from_tty", "to_string", NULL };
 +  static const char *keywords[] = {"command", "from_tty", "to_string", NULL };

However, passing the such array to PyArg_ParseTupleAndKeywords no longer
works OOTB, because PyArg_ParseTupleAndKeywords expects a "char **":

  PyArg_ParseTupleAndKeywords(PyObject *args, PyObject *kw,
                              const char *format,
			      char *keywords[], ...);

and "const char **" is not implicitly convertible to "char **".  C++
is more tolerant that C here WRT aliasing, and a const_cast<char **>
is fine.  However, to avoid having all callers do the cast themselves,
this commit defines a gdb_PyArg_ParseTupleAndKeywords function here
with a corresponding 'keywords' parameter type that does the cast in a
single place.

gdb/ChangeLog:
2017-04-05  Pedro Alves  <palves@redhat.com>

	* python/python-internal.h (gdb_PyArg_ParseTupleAndKeywords): New
	static inline function.
	* python/py-arch.c (archpy_disassemble): Constify 'keywords'
	array and use gdb_PyArg_ParseTupleAndKeywords.
	* python/py-cmd.c (cmdpy_init): Likewise.
	* python/py-finishbreakpoint.c (bpfinishpy_init): Likewise.
	* python/py-inferior.c (infpy_read_memory, infpy_write_memory)
	(infpy_search_memory): Likewise.
	* python/py-objfile.c (objfpy_add_separate_debug_file)
	(gdbpy_lookup_objfile): Likewise.
	* python/py-symbol.c (gdbpy_lookup_symbol)
	(gdbpy_lookup_global_symbol): Likewise.
	* python/py-type.c (gdbpy_lookup_type): Likewise.
	* python/py-value.c (valpy_lazy_string, valpy_string): Likewise.
	* python/python.c (execute_gdb_command, gdbpy_write, gdbpy_flush):
	Likewise.
This commit is contained in:
Pedro Alves
2017-04-05 19:21:36 +01:00
parent 0d1f4ceb39
commit 2adadf5170
12 changed files with 111 additions and 63 deletions
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28
gdb/python/python-internal.h
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@@ -316,6 +316,34 @@ struct gdb_PyGetSetDef : PyGetSetDef
{}
};
/* The 'keywords' parameter of PyArg_ParseTupleAndKeywords has type
'char **'. However, string literals are const in C++, and so to
avoid casting at every keyword array definition, we'll need to make
the keywords array an array of 'const char *'. To avoid having all
callers add a 'const_cast<char **>' themselves when passing such an
array through 'char **', we define our own version of
PyArg_ParseTupleAndKeywords here with a corresponding 'keywords'
parameter type that does the cast in a single place. (This is not
an overload of PyArg_ParseTupleAndKeywords in order to make it
clearer that we're calling our own function instead of a function
that exists in some newer Python version.) */
static inline int
gdb_PyArg_ParseTupleAndKeywords (PyObject *args, PyObject *kw,
const char *format, const char **keywords, ...)
{
va_list ap;
int res;
va_start (ap, keywords);
res = PyArg_VaParseTupleAndKeywords (args, kw, format,
const_cast<char **> (keywords),
ap);
va_end (ap);
return res;
}
/* In order to be able to parse symtab_and_line_to_sal_object function
a real symtab_and_line structure is needed. */
#include "symtab.h"