From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 46818 invoked by alias); 4 Apr 2017 18:37:53 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org Received: (qmail 45424 invoked by uid 89); 4 Apr 2017 18:37:52 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-26.9 required=5.0 tests=BAYES_00,GIT_PATCH_0,GIT_PATCH_1,GIT_PATCH_2,GIT_PATCH_3,RP_MATCHES_RCVD,SPF_HELO_PASS autolearn=ham version=3.3.2 spammy= X-HELO: mx1.redhat.com Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Tue, 04 Apr 2017 18:37:45 +0000 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id C518F3B74F for ; Tue, 4 Apr 2017 18:37:45 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com C518F3B74F Authentication-Results: ext-mx06.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx06.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=sergiodj@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com C518F3B74F Received: from localhost (unused-10-15-17-193.yyz.redhat.com [10.15.17.193]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 8CD50189EC; Tue, 4 Apr 2017 18:37:44 +0000 (UTC) From: Sergio Durigan Junior To: Pedro Alves Cc: gdb-patches@sourceware.org Subject: Re: [PATCH 14/18] -Wwrite-strings: Add a PyArg_ParseTupleAndKeywords "const char *" overload References: <1491326751-16180-1-git-send-email-palves@redhat.com> <1491326751-16180-15-git-send-email-palves@redhat.com> X-URL: https://sergiodj.net Date: Tue, 04 Apr 2017 18:37:00 -0000 In-Reply-To: <1491326751-16180-15-git-send-email-palves@redhat.com> (Pedro Alves's message of "Tue, 4 Apr 2017 18:25:47 +0100") Message-ID: <87efx8dnnr.fsf@redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-IsSubscribed: yes X-SW-Source: 2017-04/txt/msg00051.txt.bz2 On Tuesday, April 04 2017, Pedro Alves wrote: > -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 like this: > > - static char *keywords[] = {"command", "from_tty", "to_string", NULL }; > + static const char *keywords[] = {"command", "from_tty", "to_string", NULL }; > > However, passing the 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 > would be fine. > > However, to avoid having all callers add the 'const_cast' > themselves, this commit define a PyArg_ParseTupleAndKeywords overload > here with a corresponding 'keywords' parameter type that does the cast > in a single place. > > As in the PyGetSetDef patch, I'd be fine with naming this > gdb_PyArg_ParseTupleAndKeywords instead, if people would find having > our own overload confusing. As much as I like the overloading approach in general, I prefer to see our own overloads marked with the "gdb_", just to make things clearer. > BTW, this API issue was discussed years ago in the python-dev list: > > https://mail.python.org/pipermail/python-dev/2006-February/060689.html > > ... and an overload for C++ was suggested in there somewhere. > Unfortunately, it was never added. Interesting. I wonder if there's an actual bug/issue opened on their bugzilla about this. Hm, after a quick search I didn't find anything. Maybe it's worth creating one. The rest is fine by me. Thanks! > gdb/ChangeLog: > yyyy-mm-dd Pedro Alves > > * python/py-arch.c (archpy_disassemble): Constify 'keywords' > array. > * python/py-cmd.c (cmdpy_init): Constify 'keywords' array. > * python/py-finishbreakpoint.c (bpfinishpy_init): Constify > 'keywords' array. > * python/py-inferior.c (infpy_read_memory, infpy_write_memory) > (infpy_search_memory): Constify 'keywords' array. > * python/py-objfile.c (objfpy_add_separate_debug_file) > (gdbpy_lookup_objfile): Constify 'keywords' array. > * python/py-symbol.c (gdbpy_lookup_symbol) > (gdbpy_lookup_global_symbol): Constify 'keywords' array. > * python/py-type.c (gdbpy_lookup_type): Constify 'keywords' array. > * python/py-value.c (valpy_lazy_string, valpy_string): Constify > 'keywords' array. > * python/python.c (execute_gdb_command, gdbpy_write, gdbpy_flush): > Constify 'keywords' array. > * python/python-internal.h (PyArg_ParseTupleAndKeywords): New > function overload. > --- > gdb/python/py-arch.c | 2 +- > gdb/python/py-breakpoint.c | 4 ++-- > gdb/python/py-cmd.c | 6 +++--- > gdb/python/py-finishbreakpoint.c | 2 +- > gdb/python/py-inferior.c | 6 +++--- > gdb/python/py-objfile.c | 4 ++-- > gdb/python/py-symbol.c | 4 ++-- > gdb/python/py-type.c | 2 +- > gdb/python/py-value.c | 4 ++-- > gdb/python/python-internal.h | 25 +++++++++++++++++++++++++ > gdb/python/python.c | 6 +++--- > 11 files changed, 45 insertions(+), 20 deletions(-) > > diff --git a/gdb/python/py-arch.c b/gdb/python/py-arch.c > index 71d2989..48fae32 100644 > --- a/gdb/python/py-arch.c > +++ b/gdb/python/py-arch.c > @@ -116,7 +116,7 @@ archpy_name (PyObject *self, PyObject *args) > static PyObject * > archpy_disassemble (PyObject *self, PyObject *args, PyObject *kw) > { > - static char *keywords[] = { "start_pc", "end_pc", "count", NULL }; > + static const char *keywords[] = { "start_pc", "end_pc", "count", NULL }; > CORE_ADDR start, end = 0; > CORE_ADDR pc; > gdb_py_ulongest start_temp; > diff --git a/gdb/python/py-breakpoint.c b/gdb/python/py-breakpoint.c > index 724a7ed..2043d42 100644 > --- a/gdb/python/py-breakpoint.c > +++ b/gdb/python/py-breakpoint.c > @@ -637,8 +637,8 @@ bppy_get_ignore_count (PyObject *self, void *closure) > static int > bppy_init (PyObject *self, PyObject *args, PyObject *kwargs) > { > - static char *keywords[] = { "spec", "type", "wp_class", "internal", > - "temporary", NULL }; > + static const char *keywords[] = { "spec", "type", "wp_class", "internal", > + "temporary", NULL }; > const char *spec; > int type = bp_breakpoint; > int access_type = hw_write; > diff --git a/gdb/python/py-cmd.c b/gdb/python/py-cmd.c > index 3aaf7f9..8f61d9c 100644 > --- a/gdb/python/py-cmd.c > +++ b/gdb/python/py-cmd.c > @@ -490,8 +490,8 @@ cmdpy_init (PyObject *self, PyObject *args, PyObject *kw) > char *docstring = NULL; > struct cmd_list_element **cmd_list; > char *cmd_name, *pfx_name; > - static char *keywords[] = { "name", "command_class", "completer_class", > - "prefix", NULL }; > + static const char *keywords[] = { "name", "command_class", "completer_class", > + "prefix", NULL }; > PyObject *is_prefix = NULL; > int cmp; > > @@ -506,7 +506,7 @@ cmdpy_init (PyObject *self, PyObject *args, PyObject *kw) > > if (! PyArg_ParseTupleAndKeywords (args, kw, "si|iO", > keywords, &name, &cmdtype, > - &completetype, &is_prefix)) > + &completetype, &is_prefix)) > return -1; > > if (cmdtype != no_class && cmdtype != class_run > diff --git a/gdb/python/py-finishbreakpoint.c b/gdb/python/py-finishbreakpoint.c > index 106fe34..9d43d55 100644 > --- a/gdb/python/py-finishbreakpoint.c > +++ b/gdb/python/py-finishbreakpoint.c > @@ -156,7 +156,7 @@ bpfinishpy_post_stop_hook (struct gdbpy_breakpoint_object *bp_obj) > static int > bpfinishpy_init (PyObject *self, PyObject *args, PyObject *kwargs) > { > - static char *keywords[] = { "frame", "internal", NULL }; > + static const char *keywords[] = { "frame", "internal", NULL }; > struct finish_breakpoint_object *self_bpfinish = > (struct finish_breakpoint_object *) self; > PyObject *frame_obj = NULL; > diff --git a/gdb/python/py-inferior.c b/gdb/python/py-inferior.c > index 46a0aad..8b4782b 100644 > --- a/gdb/python/py-inferior.c > +++ b/gdb/python/py-inferior.c > @@ -435,7 +435,7 @@ infpy_read_memory (PyObject *self, PyObject *args, PyObject *kw) > CORE_ADDR addr, length; > gdb_byte *buffer = NULL; > PyObject *addr_obj, *length_obj, *result; > - static char *keywords[] = { "address", "length", NULL }; > + static const char *keywords[] = { "address", "length", NULL }; > > if (! PyArg_ParseTupleAndKeywords (args, kw, "OO", keywords, > &addr_obj, &length_obj)) > @@ -494,7 +494,7 @@ infpy_write_memory (PyObject *self, PyObject *args, PyObject *kw) > const gdb_byte *buffer; > CORE_ADDR addr, length; > PyObject *addr_obj, *length_obj = NULL; > - static char *keywords[] = { "address", "buffer", "length", NULL }; > + static const char *keywords[] = { "address", "buffer", "length", NULL }; > #ifdef IS_PY3K > Py_buffer pybuf; > > @@ -643,7 +643,7 @@ infpy_search_memory (PyObject *self, PyObject *args, PyObject *kw) > { > struct gdb_exception except = exception_none; > CORE_ADDR start_addr, length; > - static char *keywords[] = { "address", "length", "pattern", NULL }; > + static const char *keywords[] = { "address", "length", "pattern", NULL }; > PyObject *start_addr_obj, *length_obj; > Py_ssize_t pattern_size; > const gdb_byte *buffer; > diff --git a/gdb/python/py-objfile.c b/gdb/python/py-objfile.c > index 105d88a..ad1ec4f 100644 > --- a/gdb/python/py-objfile.c > +++ b/gdb/python/py-objfile.c > @@ -432,7 +432,7 @@ objfpy_is_valid (PyObject *self, PyObject *args) > static PyObject * > objfpy_add_separate_debug_file (PyObject *self, PyObject *args, PyObject *kw) > { > - static char *keywords[] = { "file_name", NULL }; > + static const char *keywords[] = { "file_name", NULL }; > objfile_object *obj = (objfile_object *) self; > const char *file_name; > > @@ -559,7 +559,7 @@ objfpy_lookup_objfile_by_build_id (const char *build_id) > PyObject * > gdbpy_lookup_objfile (PyObject *self, PyObject *args, PyObject *kw) > { > - static char *keywords[] = { "name", "by_build_id", NULL }; > + static const char *keywords[] = { "name", "by_build_id", NULL }; > const char *name; > PyObject *by_build_id_obj = NULL; > int by_build_id; > diff --git a/gdb/python/py-symbol.c b/gdb/python/py-symbol.c > index b71cfb4..de44c06 100644 > --- a/gdb/python/py-symbol.c > +++ b/gdb/python/py-symbol.c > @@ -373,7 +373,7 @@ gdbpy_lookup_symbol (PyObject *self, PyObject *args, PyObject *kw) > int domain = VAR_DOMAIN; > struct field_of_this_result is_a_field_of_this; > const char *name; > - static char *keywords[] = { "name", "block", "domain", NULL }; > + static const char *keywords[] = { "name", "block", "domain", NULL }; > struct symbol *symbol = NULL; > PyObject *block_obj = NULL, *sym_obj, *bool_obj; > const struct block *block = NULL; > @@ -443,7 +443,7 @@ gdbpy_lookup_global_symbol (PyObject *self, PyObject *args, PyObject *kw) > { > int domain = VAR_DOMAIN; > const char *name; > - static char *keywords[] = { "name", "domain", NULL }; > + static const char *keywords[] = { "name", "domain", NULL }; > struct symbol *symbol = NULL; > PyObject *sym_obj; > > diff --git a/gdb/python/py-type.c b/gdb/python/py-type.c > index f071006..4f4ede1 100644 > --- a/gdb/python/py-type.c > +++ b/gdb/python/py-type.c > @@ -1347,7 +1347,7 @@ type_object_to_type (PyObject *obj) > PyObject * > gdbpy_lookup_type (PyObject *self, PyObject *args, PyObject *kw) > { > - static char *keywords[] = { "name", "block", NULL }; > + static const char *keywords[] = { "name", "block", NULL }; > const char *type_name = NULL; > struct type *type = NULL; > PyObject *block_obj = NULL; > diff --git a/gdb/python/py-value.c b/gdb/python/py-value.c > index bb42e8b..1a82af5 100644 > --- a/gdb/python/py-value.c > +++ b/gdb/python/py-value.c > @@ -431,7 +431,7 @@ valpy_lazy_string (PyObject *self, PyObject *args, PyObject *kw) > gdb_py_longest length = -1; > struct value *value = ((value_object *) self)->value; > const char *user_encoding = NULL; > - static char *keywords[] = { "encoding", "length", NULL }; > + static const char *keywords[] = { "encoding", "length", NULL }; > PyObject *str_obj = NULL; > > if (!PyArg_ParseTupleAndKeywords (args, kw, "|s" GDB_PY_LL_ARG, keywords, > @@ -526,7 +526,7 @@ valpy_string (PyObject *self, PyObject *args, PyObject *kw) > const char *user_encoding = NULL; > const char *la_encoding = NULL; > struct type *char_type; > - static char *keywords[] = { "encoding", "errors", "length", NULL }; > + static const char *keywords[] = { "encoding", "errors", "length", NULL }; > > if (!PyArg_ParseTupleAndKeywords (args, kw, "|ssi", keywords, > &user_encoding, &errors, &length)) > diff --git a/gdb/python/python-internal.h b/gdb/python/python-internal.h > index 8fc89cd..76f7443 100644 > --- a/gdb/python/python-internal.h > +++ b/gdb/python/python-internal.h > @@ -318,6 +318,31 @@ struct gdb_PyGetSetDef : PyGetSetDef > > #define PyGetSetDef gdb_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' themselves when passing such an > + array through 'char **', we define a PyArg_ParseTupleAndKeywords > + overload here with a corresponding 'keywords' parameter type that > + does the cast in a single place. */ > + > +static inline int > +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 (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" > diff --git a/gdb/python/python.c b/gdb/python/python.c > index a7aff53..5a46493 100644 > --- a/gdb/python/python.c > +++ b/gdb/python/python.c > @@ -572,7 +572,7 @@ execute_gdb_command (PyObject *self, PyObject *args, PyObject *kw) > const char *arg; > PyObject *from_tty_obj = NULL, *to_string_obj = NULL; > int from_tty, to_string; > - static char *keywords[] = {"command", "from_tty", "to_string", NULL }; > + static const char *keywords[] = { "command", "from_tty", "to_string", NULL }; > > if (! PyArg_ParseTupleAndKeywords (args, kw, "s|O!O!", keywords, &arg, > &PyBool_Type, &from_tty_obj, > @@ -1047,7 +1047,7 @@ static PyObject * > gdbpy_write (PyObject *self, PyObject *args, PyObject *kw) > { > const char *arg; > - static char *keywords[] = {"text", "stream", NULL }; > + static const char *keywords[] = { "text", "stream", NULL }; > int stream_type = 0; > > if (! PyArg_ParseTupleAndKeywords (args, kw, "s|i", keywords, &arg, > @@ -1088,7 +1088,7 @@ gdbpy_write (PyObject *self, PyObject *args, PyObject *kw) > static PyObject * > gdbpy_flush (PyObject *self, PyObject *args, PyObject *kw) > { > - static char *keywords[] = {"stream", NULL }; > + static const char *keywords[] = { "stream", NULL }; > int stream_type = 0; > > if (! PyArg_ParseTupleAndKeywords (args, kw, "|i", keywords, > -- > 2.5.5 -- Sergio GPG key ID: 237A 54B1 0287 28BF 00EF 31F4 D0EB 7628 65FC 5E36 Please send encrypted e-mail if possible http://sergiodj.net/