Re: RFC: Python gdb.Type method returning optimized out gdb.Value

[Alexander Smundak <asmundak@google.com>]

Thank you for the quick review.
Edited NEWS, renamed `create_optimized_out' to `optimized_out',
elided 'unavailable' from description, added blank line.
PTAL.

gdb/doc/ChangeLog:

2015-04-07  Sasha Smundak  <asmundak@google.com>

    * python.texi: New method documented.

gdb/ChangeLog:

2015-04-07  Sasha Smundak  <asmundak@google.com>

    * NEWS: Mention gdb.Type.optimized_out method.
    * python/py-type.c (typy_optimized_out):  New function.

gdb/testsuite/ChangeLog:

2015-04-07  Sasha Smundak  <asmundak@google.com>

    * gdb.python/py-type.exp: New test.

diff --git a/gdb/NEWS b/gdb/NEWS
index 884c381..ebb573a 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -37,6 +37,8 @@
      which is the name of the objfile as specified by the user,
      without, for example, resolving symlinks.
   ** You can now write frame unwinders in Python.
+  ** gdb.Type objects have a new method "optimized_out",
+     returning optimized out gdb.Value instance of this type.

 * New commands

diff --git a/gdb/doc/python.texi b/gdb/doc/python.texi
index 098d718..091521c6 100644
--- a/gdb/doc/python.texi
+++ b/gdb/doc/python.texi
@@ -1060,6 +1060,11 @@ If @var{block} is given, then @var{name} is
looked up in that scope.
 Otherwise, it is searched for globally.
 @end defun

+@defun Type.optimized_out ()
+Return @code{gdb.Value} instance of this type whose value is optimized
+out.  This allows a frame decorator to indicate that the value of an
+argument or a local variable is not known.
+@end defun

 Each type has a code, which indicates what category this type falls
 into.  The available type categories are represented by constants
diff --git a/gdb/python/py-type.c b/gdb/python/py-type.c
index 39376a1..0461b26 100644
--- a/gdb/python/py-type.c
+++ b/gdb/python/py-type.c
@@ -1181,6 +1181,15 @@ typy_nonzero (PyObject *self)
   return 1;
 }

+/* Return optimized out value of this type.  */
+
+static PyObject *
+typy_optimized_out (PyObject *self, PyObject *args)
+{
+  struct type *type = ((type_object *) self)->type;
+  return value_to_value_object (allocate_optimized_out_value (type));
+}
+
 /* Return a gdb.Field object for the field named by the argument.  */

 static PyObject *
@@ -1493,6 +1502,8 @@ They are first class values." },
   { "const", typy_const, METH_NOARGS,
     "const () -> Type\n\
 Return a const variant of this type." },
+  { "optimized_out", typy_optimized_out, METH_NOARGS,
+"optimized_out() -> Value\nReturn optimized out value of this type." },
   { "fields", typy_fields, METH_NOARGS,
     "fields () -> list\n\
 Return a list holding all the fields of this type.\n\
diff --git a/gdb/testsuite/gdb.python/py-type.exp
b/gdb/testsuite/gdb.python/py-type.exp
index c4c8d9f..2edbfe3 100644
--- a/gdb/testsuite/gdb.python/py-type.exp
+++ b/gdb/testsuite/gdb.python/py-type.exp
@@ -253,6 +253,9 @@ gdb_test "python print
gdb.lookup_type('char').array(1, 0)" \
 gdb_test "python print gdb.lookup_type('char').array(1, -1)" \
     "Array length must not be negative.*"

+gdb_test "python print gdb.lookup_type('int').optimized_out()" \
+    "<optimized out>"
+
 with_test_prefix "lang_c" {
     runto_bp "break to inspect struct and array."
     test_fields "c"

On Tue, Apr 7, 2015 at 10:44 AM, Doug Evans <dje@google.com> wrote:
> Alexander Smundak writes:
>  > Provide the ability for a a Python frame decorator to indicate that
>  > a value is not available.
>  >
>  > doc/ChangeLog:
>  >
>  > 2015-04-03  Sasha Smundak  <asmundak@google.com>
>  >
>  >     * python.texi:New method documented.
>  >
>  > gdb/ChangeLog:
>  >
>  > 2015-04-03  Sasha Smundak  <asmundak@google.com>
>  >
>  >    * python/py-type.c (typy_create_optimized_out): New function.
>  >
>  > testsuite/ChangeLog:
>  >
>  > 2015-04-03  Sasha Smundak  <asmundak@google.com>
>  >
>  >    * gdb.python/py-type.exp: New test.
>
> Hi.
> A few of nits.
>
> The terms "unavailable" and "optimized out" have different meanings
> in gdb.  See their definitions at the top of value.h.
> Also see the comments for struct value.{unavailable,optimized_out}
> in value.c.  I don't know if python frame decorators would want to specify
> a value as being unavailable (in gdb parlance), but don't use "unavailable"
> in the documentation of "optimized out".
>
> The "create_" in "create_optimized_out" is incongruous with the
> rest of gdb.Type methods.  E.g., we have "array" not "create_array",
> "vector" not "create_vector", "const" not "create_const", and so on.
> Does "optimized_out" read well to you?
>
> A NEWS entry is needed.
>
>  >
>  > diff --git a/gdb/doc/python.texi b/gdb/doc/python.texi
>  > index 098d718..7c2d0bc 100644
>  > --- a/gdb/doc/python.texi
>  > +++ b/gdb/doc/python.texi
>  > @@ -1060,6 +1060,11 @@ If @var{block} is given, then @var{name} is
>  > looked up in that scope.
>  >  Otherwise, it is searched for globally.
>  >  @end defun
>  >
>  > +@defun Type.create_optimized_out ()
>  > +Return @code{gdb.Value} instance of this type whose value is optimized
>  > +out.  Allows a frame decorator to indicate that an argument or local
>  > +variable value is unavailable.
>  > +@end defun
>  >
>  >  Each type has a code, which indicates what category this type falls
>  >  into.  The available type categories are represented by constants
>  > diff --git a/gdb/python/py-type.c b/gdb/python/py-type.c
>  > index 39376a1..186cc19 100644
>  > --- a/gdb/python/py-type.c
>  > +++ b/gdb/python/py-type.c
>  > @@ -1181,6 +1181,14 @@ typy_nonzero (PyObject *self)
>  >    return 1;
>  >  }
>  >
>  > +/* Return optimized out value of this type.  */
>
> blank line
>
>  > +static PyObject *
>  > +typy_create_optimized_out (PyObject *self, PyObject *args)
>  > +{
>  > +  struct type *type = ((type_object *) self)->type;
>  > +  return value_to_value_object (allocate_optimized_out_value (type));
>  > +}
>  > +
>  >  /* Return a gdb.Field object for the field named by the argument.  */
>  >
>  >  static PyObject *
>  > @@ -1493,6 +1501,8 @@ They are first class values." },
>  >    { "const", typy_const, METH_NOARGS,
>  >      "const () -> Type\n\
>  >  Return a const variant of this type." },
>  > +  { "create_optimized_out", typy_create_optimized_out, METH_NOARGS,
>  > +"create_optimized_out() -> Value\nReturn optimized out value of this type." },
>  >    { "fields", typy_fields, METH_NOARGS,
>  >      "fields () -> list\n\
>  >  Return a list holding all the fields of this type.\n\
>  > diff --git a/gdb/testsuite/gdb.python/py-type.exp
>  > b/gdb/testsuite/gdb.python/py-type.exp
>  > index c4c8d9f..c73f831 100644
>  > --- a/gdb/testsuite/gdb.python/py-type.exp
>  > +++ b/gdb/testsuite/gdb.python/py-type.exp
>  > @@ -253,6 +253,9 @@ gdb_test "python print
>  > gdb.lookup_type('char').array(1, 0)" \
>  >  gdb_test "python print gdb.lookup_type('char').array(1, -1)" \
>  >      "Array length must not be negative.*"
>  >
>  > +gdb_test "python print gdb.lookup_type('int').create_optimized_out()" \
>  > +    "<optimized out>"
>  > +
>  >  with_test_prefix "lang_c" {
>  >      runto_bp "break to inspect struct and array."
>  >      test_fields "c"
>
> --
> /dje