-Wwrite-strings: Wrap PyGetSetDef for construction with string literals

Unfortunately, PyGetSetDef's 'name' and 'doc' members are 'char *'
instead of 'const char *', meaning that in order to list-initialize
PyGetSetDef arrays using string literals requires writing explicit
'char *' casts.  For example:

    static PyGetSetDef value_object_getset[] = {
   -  { "address", valpy_get_address, NULL, "The address of the value.",
   +  { (char *) "address", valpy_get_address, NULL,
   +    (char *) "The address of the value.",
	NULL },
   -  { "is_optimized_out", valpy_get_is_optimized_out, NULL,
   -    "Boolean telling whether the value is optimized "
   +  { (char *) "is_optimized_out", valpy_get_is_optimized_out, NULL,
   +    (char *) "Boolean telling whether the value is optimized "
	"out (i.e., not available).",
	NULL },
   -  { "type", valpy_get_type, NULL, "Type of the value.", NULL },
   -  { "dynamic_type", valpy_get_dynamic_type, NULL,
   -    "Dynamic type of the value.", NULL },
   -  { "is_lazy", valpy_get_is_lazy, NULL,
   -    "Boolean telling whether the value is lazy (not fetched yet\n\
   +  { (char *) "type", valpy_get_type, NULL,
   +    (char *) "Type of the value.", NULL },
   +  { (char *) "dynamic_type", valpy_get_dynamic_type, NULL,
   +    (char *) "Dynamic type of the value.", NULL },
   +  { (char *) "is_lazy", valpy_get_is_lazy, NULL,
   +    (char *) "Boolean telling whether the value is lazy (not fetched yet\n\
    from the inferior).  A lazy value is fetched when needed, or when\n\
    the \"fetch_lazy()\" method is called.", NULL },
      {NULL}  /* Sentinel */

We have ~20 such arrays, and I first wrote a patch that fixed all of
them like that...  It's not pretty...

One way to make these a bit less ugly would be add a new macro that
hides the casts, like:

  #define GDBPY_GSDEF(NAME, GET, SET, DOC, CLOSURE) \
     { (char *) NAME, GET, SET, (char *) DOC, CLOSURE }

and then use it like:

    static PyGetSetDef value_object_getset[] = {
       GDBPY_GSDEF ("address", valpy_get_address, NULL,
       		    "The address of the value.", NULL),
       GDBPY_GSDEF ("is_optimized_out", valpy_get_is_optimized_out, NULL,
       		    "Boolean telling whether the value is optimized ", NULL),
      {NULL}  /* Sentinel */
    };

But since we have C++11, which gives us constexpr and list
initialization, I thought of a way that requires no changes where the
arrays are initialized:

We add a new type that extends PyGetSetDef (called gdb_PyGetSetDef),
and add constexpr constructors that accept const 'name' and 'doc', and
then list/aggregate initialization simply "calls" these matching
constructors instead.

I put "calls" in quotes, because given "constexpr", it's all done at
compile time, and there's no overhead either in binary size or at run
time.  In fact, we get identical binaries, before/after this change.

Unlike the fixes that fix some old Python API to match the API of more
recent Python, this switches to using explicit "gdb_PyGetSetDef"
everywhere, just to be clear that we are using our own version of it.

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

	* python/python-internal.h (gdb_PyGetSetDef): New type.
	* python/py-block.c (block_object_getset)
	(breakpoint_object_getset): Now a gdb_PyGetSetDef array.
	* python/py-event.c (event_object_getset)
	(finish_breakpoint_object_getset): Likewise.
	* python/py-inferior.c (inferior_object_getset): Likewise.
	* python/py-infthread.c (thread_object_getset): Likewise.
	* python/py-lazy-string.c (lazy_string_object_getset): Likewise.
	* python/py-linetable.c (linetable_entry_object_getset): Likewise.
	* python/py-objfile.c (objfile_getset): Likewise.
	* python/py-progspace.c (pspace_getset): Likewise.
	* python/py-record-btrace.c (btpy_insn_getset, btpy_call_getset):
	Likewise.
	* python/py-record.c (recpy_record_getset): Likewise.
	* python/py-symbol.c (symbol_object_getset): Likewise.
	* python/py-symtab.c (symtab_object_getset, sal_object_getset):
	Likewise.
	* python/py-type.c (type_object_getset, field_object_getset):
	Likewise.
	* python/py-value.c (value_object_getset): Likewise.

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 9430d3a273a3ebb66419f43b4effd2b7728699e8..28557c2700502e895f9abcaec5b16f583ae714f2 100644 (file)
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,26 @@
+2017-04-05  Pedro Alves  <palves@redhat.com>
+
+       * python/python-internal.h (gdb_PyGetSetDef): New type.
+       * python/py-block.c (block_object_getset)
+       (breakpoint_object_getset): Now a gdb_PyGetSetDef array.
+       * python/py-event.c (event_object_getset)
+       (finish_breakpoint_object_getset): Likewise.
+       * python/py-inferior.c (inferior_object_getset): Likewise.
+       * python/py-infthread.c (thread_object_getset): Likewise.
+       * python/py-lazy-string.c (lazy_string_object_getset): Likewise.
+       * python/py-linetable.c (linetable_entry_object_getset): Likewise.
+       * python/py-objfile.c (objfile_getset): Likewise.
+       * python/py-progspace.c (pspace_getset): Likewise.
+       * python/py-record-btrace.c (btpy_insn_getset, btpy_call_getset):
+       Likewise.
+       * python/py-record.c (recpy_record_getset): Likewise.
+       * python/py-symbol.c (symbol_object_getset): Likewise.
+       * python/py-symtab.c (symtab_object_getset, sal_object_getset):
+       Likewise.
+       * python/py-type.c (type_object_getset, field_object_getset):
+       Likewise.
+       * python/py-value.c (value_object_getset): Likewise.
+
 2017-04-05  Pedro Alves  <palves@redhat.com>
 
        * python/python-internal.h (gdb_PyObject_CallMethod)

diff --git a/gdb/python/py-block.c b/gdb/python/py-block.c
index f477d4a63e199a51130814665805c663f6857298..840c842e85a3161685af3c1df2ecadbb16422979 100644 (file)
--- a/gdb/python/py-block.c
+++ b/gdb/python/py-block.c
@@ -461,7 +461,7 @@ Return true if this block is valid, false if not." },
   {NULL}  /* Sentinel */
 };
 
-static PyGetSetDef block_object_getset[] = {
+static gdb_PyGetSetDef block_object_getset[] = {
   { "start", blpy_get_start, NULL, "Start address of the block.", NULL },
   { "end", blpy_get_end, NULL, "End address of the block.", NULL },
   { "function", blpy_get_function, NULL,

diff --git a/gdb/python/py-breakpoint.c b/gdb/python/py-breakpoint.c
index 724a7ed41c96c54cf849d8f290ff8bc9456e1575..34f46fb7a42a3c3a5106ebace68399f8c44290f4 100644 (file)
--- a/gdb/python/py-breakpoint.c
+++ b/gdb/python/py-breakpoint.c
@@ -1048,7 +1048,7 @@ local_setattro (PyObject *self, PyObject *name, PyObject *v)
   return PyObject_GenericSetAttr ((PyObject *)self, name, v);
 }
 
-static PyGetSetDef breakpoint_object_getset[] = {
+static gdb_PyGetSetDef breakpoint_object_getset[] = {
   { "enabled", bppy_get_enabled, bppy_set_enabled,
     "Boolean telling whether the breakpoint is enabled.", NULL },
   { "silent", bppy_get_silent, bppy_set_silent,

diff --git a/gdb/python/py-event.c b/gdb/python/py-event.c
index 127dcc742608ddb4f59300448f340291733ce95e..dc1d73e78b4ba5898969c5a9ea56a882e09e6c49 100644 (file)
--- a/gdb/python/py-event.c
+++ b/gdb/python/py-event.c
@@ -114,7 +114,7 @@ evpy_emit_event (PyObject *event,
   return 0;
 }
 
-static PyGetSetDef event_object_getset[] =
+static gdb_PyGetSetDef event_object_getset[] =
 {
   { "__dict__", gdb_py_generic_dict, NULL,
     "The __dict__ for this event.", &event_object_type },

diff --git a/gdb/python/py-finishbreakpoint.c b/gdb/python/py-finishbreakpoint.c
index 106fe34e85aa1573ae857591a2dba96baec6b614..76189b8a1deb472eb36b8f191c2ff329b95d74a6 100644 (file)
--- a/gdb/python/py-finishbreakpoint.c
+++ b/gdb/python/py-finishbreakpoint.c
@@ -426,7 +426,7 @@ gdbpy_initialize_finishbreakpoints (void)
   return 0;
 }
 
-static PyGetSetDef finish_breakpoint_object_getset[] = {
+static gdb_PyGetSetDef finish_breakpoint_object_getset[] = {
   { "return_value", bpfinishpy_get_returnvalue, NULL,
   "gdb.Value object representing the return value, if any. \
 None otherwise.", NULL },

diff --git a/gdb/python/py-inferior.c b/gdb/python/py-inferior.c
index 46a0aad593c08e6e98a6c704da7dfb03b2e622de..77fc543dcabcb409c4241e04ce86b9aeda84e1c4 100644 (file)
--- a/gdb/python/py-inferior.c
+++ b/gdb/python/py-inferior.c
@@ -827,7 +827,7 @@ gdbpy_initialize_inferior (void)
                                 &membuf_object_type);
 }
 
-static PyGetSetDef inferior_object_getset[] =
+static gdb_PyGetSetDef inferior_object_getset[] =
 {
   { "num", infpy_get_num, NULL, "ID of inferior, as assigned by GDB.", NULL },
   { "pid", infpy_get_pid, NULL, "PID of inferior, as assigned by the OS.",

diff --git a/gdb/python/py-infthread.c b/gdb/python/py-infthread.c
index 5482bf9ea19a69f5eb7bfdd25ab37e4316bd915a..626c15cedb56ca1789d5dd075c8592decdfd982f 100644 (file)
--- a/gdb/python/py-infthread.c
+++ b/gdb/python/py-infthread.c
@@ -304,7 +304,7 @@ gdbpy_initialize_thread (void)
                                 (PyObject *) &thread_object_type);
 }
 
-static PyGetSetDef thread_object_getset[] =
+static gdb_PyGetSetDef thread_object_getset[] =
 {
   { "name", thpy_get_name, thpy_set_name,
     "The name of the thread, as set by the user or the OS.", NULL },

diff --git a/gdb/python/py-lazy-string.c b/gdb/python/py-lazy-string.c
index ab3f411743951e1f94cd89bd80383686417242c3..19990330601ad1403445d788909e0d5fdcf8fed6 100644 (file)
--- a/gdb/python/py-lazy-string.c
+++ b/gdb/python/py-lazy-string.c
@@ -300,7 +300,7 @@ static PyMethodDef lazy_string_object_methods[] = {
 };
 
 
-static PyGetSetDef lazy_string_object_getset[] = {
+static gdb_PyGetSetDef lazy_string_object_getset[] = {
   { "address", stpy_get_address, NULL, "Address of the string.", NULL },
   { "encoding", stpy_get_encoding, NULL, "Encoding of the string.", NULL },
   { "length", stpy_get_length, NULL, "Length of the string.", NULL },

diff --git a/gdb/python/py-linetable.c b/gdb/python/py-linetable.c
index a5e57b0d365b1472653876aa8009f9b07c7a0048..8d17aabbf9d96f06f0c20aa5e41f7a2e3fb40961 100644 (file)
--- a/gdb/python/py-linetable.c
+++ b/gdb/python/py-linetable.c
@@ -550,7 +550,7 @@ PyTypeObject ltpy_iterator_object_type = {
 };
 
 
-static PyGetSetDef linetable_entry_object_getset[] = {
+static gdb_PyGetSetDef linetable_entry_object_getset[] = {
   { "line", ltpy_entry_get_line, NULL,
     "The line number in the source file.", NULL },
   { "pc", ltpy_entry_get_pc, NULL,

diff --git a/gdb/python/py-objfile.c b/gdb/python/py-objfile.c
index 105d88a27c7aeb1d7eaa949c9c762491f39df5af..6a47c1703409fca8032ed007a7c32138428d6b9f 100644 (file)
--- a/gdb/python/py-objfile.c
+++ b/gdb/python/py-objfile.c
@@ -670,7 +670,7 @@ Add FILE_NAME to the list of files containing debug info for the objfile." },
   { NULL }
 };
 
-static PyGetSetDef objfile_getset[] =
+static gdb_PyGetSetDef objfile_getset[] =
 {
   { "__dict__", gdb_py_generic_dict, NULL,
     "The __dict__ for this objfile.", &objfile_object_type },

diff --git a/gdb/python/py-progspace.c b/gdb/python/py-progspace.c
index 1e06a75d2f7857497e2bd9c29cf6a17506dfe2bf..edabba4a002f5ac925d33cb00b2dab4296fe807f 100644 (file)
--- a/gdb/python/py-progspace.c
+++ b/gdb/python/py-progspace.c
@@ -378,7 +378,7 @@ gdbpy_initialize_pspace (void)
 
 \f
 
-static PyGetSetDef pspace_getset[] =
+static gdb_PyGetSetDef pspace_getset[] =
 {
   { "__dict__", gdb_py_generic_dict, NULL,
     "The __dict__ for this progspace.", &pspace_object_type },

diff --git a/gdb/python/py-record-btrace.c b/gdb/python/py-record-btrace.c
index c8163326d01cfec37cc834377a3b6b7b3f3f6695..6d08121376e4b5bebf07cc4140afc17f837e23d9 100644 (file)
--- a/gdb/python/py-record-btrace.c
+++ b/gdb/python/py-record-btrace.c
@@ -903,7 +903,7 @@ recpy_bt_goto (PyObject *self, PyObject *args)
 
 /* BtraceInstruction members.  */
 
-struct PyGetSetDef btpy_insn_getset[] =
+struct gdb_PyGetSetDef btpy_insn_getset[] =
 {
   { "number", btpy_number, NULL, "instruction number", NULL},
   { "error", btpy_insn_error, NULL, "error number for gaps", NULL},
@@ -920,7 +920,7 @@ executed speculatively", NULL},
 
 /* BtraceFunctionCall members.  */
 
-static PyGetSetDef btpy_call_getset[] =
+static gdb_PyGetSetDef btpy_call_getset[] =
 {
   { "number", btpy_number, NULL, "function call number", NULL},
   { "level", btpy_call_level, NULL, "call stack level", NULL},

diff --git a/gdb/python/py-record.c b/gdb/python/py-record.c
index 72922a41db2a34b22cd52dae79314fef02506533..60c0a7ce92bcdea49ad748a96db4442ce44f24a6 100644 (file)
--- a/gdb/python/py-record.c
+++ b/gdb/python/py-record.c
@@ -175,7 +175,7 @@ Rewind to given location."},
 
 /* Record member list.  */
 
-static PyGetSetDef recpy_record_getset[] = {
+static gdb_PyGetSetDef recpy_record_getset[] = {
   { "ptid", recpy_ptid, NULL, "Current thread.", NULL },
   { "method", recpy_method, NULL, "Current recording method.", NULL },
   { "format", recpy_format, NULL, "Current recording format.", NULL },

diff --git a/gdb/python/py-symbol.c b/gdb/python/py-symbol.c
index b71cfb404fe75122035ced7477fea5a384d5ff18..05b002fe725cf6c002d5fedb73fab9f6fe408b6c 100644 (file)
--- a/gdb/python/py-symbol.c
+++ b/gdb/python/py-symbol.c
@@ -560,7 +560,7 @@ gdbpy_initialize_symbols (void)
 
 \f
 
-static PyGetSetDef symbol_object_getset[] = {
+static gdb_PyGetSetDef symbol_object_getset[] = {
   { "type", sympy_get_type, NULL,
     "Type of the symbol.", NULL },
   { "symtab", sympy_get_symtab, NULL,

diff --git a/gdb/python/py-symtab.c b/gdb/python/py-symtab.c
index 09cab22182078f7d4ad5d267f075a221b1e57778..53b160e5d2c9a3792774af4a1114635006e0ed0a 100644 (file)
--- a/gdb/python/py-symtab.c
+++ b/gdb/python/py-symtab.c
@@ -544,7 +544,7 @@ gdbpy_initialize_symtabs (void)
 
 \f
 
-static PyGetSetDef symtab_object_getset[] = {
+static gdb_PyGetSetDef symtab_object_getset[] = {
   { "filename", stpy_get_filename, NULL,
     "The symbol table's source filename.", NULL },
   { "objfile", stpy_get_objfile, NULL, "The symtab's objfile.",
@@ -606,7 +606,7 @@ PyTypeObject symtab_object_type = {
   symtab_object_getset           /*tp_getset */
 };
 
-static PyGetSetDef sal_object_getset[] = {
+static gdb_PyGetSetDef sal_object_getset[] = {
   { "symtab", salpy_get_symtab, NULL, "Symtab object.", NULL },
   { "pc", salpy_get_pc, NULL, "Return the symtab_and_line's pc.", NULL },
   { "last", salpy_get_last, NULL,

diff --git a/gdb/python/py-type.c b/gdb/python/py-type.c
index f0710061f748779d6b0150b4b9a89d1ef5a734bc..12b631086d996d5953be1a95d80f304bc350be22 100644 (file)
--- a/gdb/python/py-type.c
+++ b/gdb/python/py-type.c
@@ -1413,7 +1413,7 @@ gdbpy_initialize_types (void)
 
 \f
 
-static PyGetSetDef type_object_getset[] =
+static gdb_PyGetSetDef type_object_getset[] =
 {
   { "code", typy_get_code, NULL,
     "The code for this type.", NULL },
@@ -1587,7 +1587,7 @@ PyTypeObject type_object_type =
   0,                             /* tp_new */
 };
 
-static PyGetSetDef field_object_getset[] =
+static gdb_PyGetSetDef field_object_getset[] =
 {
   { "__dict__", gdb_py_generic_dict, NULL,
     "The __dict__ for this field.", &field_object_type },

diff --git a/gdb/python/py-value.c b/gdb/python/py-value.c
index bb42e8b88e65486ca2b3e38fef5e4cc18d5e9321..9c0470f8127b9c906875e48f72e154d0a8c0c657 100644 (file)
--- a/gdb/python/py-value.c
+++ b/gdb/python/py-value.c
@@ -1767,7 +1767,7 @@ gdbpy_initialize_values (void)
 
 \f
 
-static PyGetSetDef value_object_getset[] = {
+static gdb_PyGetSetDef value_object_getset[] = {
   { "address", valpy_get_address, NULL, "The address of the value.",
     NULL },
   { "is_optimized_out", valpy_get_is_optimized_out, NULL,

diff --git a/gdb/python/python-internal.h b/gdb/python/python-internal.h
index 55efd75a8b6421106a5cfc0d4f9b2436f83dd8db..027faa59fa4b8ed0ed148f74e83e00a06b89ecb1 100644 (file)
--- a/gdb/python/python-internal.h
+++ b/gdb/python/python-internal.h
@@ -286,6 +286,36 @@ gdb_PySys_SetPath (const GDB_PYSYS_SETPATH_CHAR *path)
 
 #define PySys_SetPath gdb_PySys_SetPath
 
+/* Wrap PyGetSetDef to allow convenient construction with string
+   literals.  Unfortunately, PyGetSetDef's 'name' and 'doc' members
+   are 'char *' instead of 'const char *', meaning that in order to
+   list-initialize PyGetSetDef arrays with string literals (and
+   without the wrapping below) would require writing explicit 'char *'
+   casts.  Instead, we extend PyGetSetDef and add constexpr
+   constructors that accept const 'name' and 'doc', hiding the ugly
+   casts here in a single place.  */
+
+struct gdb_PyGetSetDef : PyGetSetDef
+{
+  constexpr gdb_PyGetSetDef (const char *name_, getter get_, setter set_,
+                            const char *doc_, void *closure_)
+    : PyGetSetDef {const_cast<char *> (name_), get_, set_,
+                  const_cast<char *> (doc_), closure_}
+  {}
+
+  /* Alternative constructor that allows omitting the closure in list
+     initialization.  */
+  constexpr gdb_PyGetSetDef (const char *name_, getter get_, setter set_,
+                            const char *doc_)
+    : gdb_PyGetSetDef {name_, get_, set_, doc_, NULL}
+  {}
+
+  /* Constructor for the sentinel entries.  */
+  constexpr gdb_PyGetSetDef (std::nullptr_t)
+    : gdb_PyGetSetDef {NULL, NULL, NULL, NULL, NULL}
+  {}
+};
+
 /* 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"