[PATCH 1/2] Guile: add value-reference-value

[Andrew Burgess]

* George Barrett via Gdb-patches <gdb-patches@sourceware.org> [2021-04-26 10:49:32 +1000]:

> The Guile API doesn't currently have an equivalent to the Python API's
> gdb.Value.reference_value(). This commit adds a procedure with
> equivalent semantics to the Guile API.

I was comparing your gdbscm_value_reference_value with Python's
valpy_reference_value and noticed that you had TYPE_CODE_REF while the
Python code used a variable.

This is because Python has two methods reference_value and
rvalue_reference_value, sadly the second of these is not documented.

Given the similarity between reference_value and
rvalue_reference_value, do you think you could add the equivalent of
both of these to guile please?  Feel free to document both of these
for guile.

That would be great, thanks!
Andrew


> 
> gdb/ChangeLog:
> 
> 2021-04-26  George Barrett  <bob@bob131.so>
> 
> 	guile/scm-value.c (gdbscm_value_reference_value): Add
> 	implementation of value-reference-value procedure.
> 	(value_functions): Add value-reference-value procedure.
> 
> gdb/doc/ChangeLog:
> 
> 2021-04-26  George Barrett  <bob@bob131.so>
> 
> 	guile.texi (Values From Inferior In Guile): Add documentation
> 	for value-reference-value.
> 
> gdb/testsuite/ChangeLog:
> 
> 2021-04-26  George Barrett  <bob@bob131.so>
> 
> 	gdb.guile/scm-value.exp (test_value_in_inferior): Add test
> 	for value-reference-value.
> ---
>  gdb/doc/guile.texi                    |  5 +++++
>  gdb/guile/scm-value.c                 | 23 +++++++++++++++++++++++
>  gdb/testsuite/gdb.guile/scm-value.exp |  3 +++
>  3 files changed, 31 insertions(+)
> 
> diff --git a/gdb/doc/guile.texi b/gdb/doc/guile.texi
> index 649dac559ad..eed94366027 100644
> --- a/gdb/doc/guile.texi
> +++ b/gdb/doc/guile.texi
> @@ -801,6 +801,11 @@ The @code{<gdb:value>} object @code{scm-val} is identical to that
>  corresponding to @code{val}.
>  @end deffn
>  
> +@deffn {Scheme Procedure} value-reference-value value
> +Return a new @code{<gdb:value>} object which is a reference to the value
> +encapsulated by @code{<gdb:value>} object @var{value}.
> +@end deffn
> +
>  @deffn {Scheme Procedure} value-field value field-name
>  Return field @var{field-name} from @code{<gdb:value>} object @var{value}.
>  @end deffn
> diff --git a/gdb/guile/scm-value.c b/gdb/guile/scm-value.c
> index 59995169cd0..dc59633ec6f 100644
> --- a/gdb/guile/scm-value.c
> +++ b/gdb/guile/scm-value.c
> @@ -487,6 +487,24 @@ gdbscm_value_referenced_value (SCM self)
>      });
>  }
>  
> +/* (value-reference-value <gdb:value>) -> <gdb:value> */
> +
> +static SCM
> +gdbscm_value_reference_value (SCM self)
> +{
> +  value_smob *v_smob
> +    = vlscm_get_value_smob_arg_unsafe (self, SCM_ARG1, FUNC_NAME);
> +  struct value *value = v_smob->value;
> +
> +  return gdbscm_wrap ([=]
> +    {
> +      scoped_value_mark free_values;
> +
> +      struct value *res_val = value_ref (value, TYPE_CODE_REF);
> +      return vlscm_scm_from_value (res_val);
> +    });
> +}
> +
>  /* (value-type <gdb:value>) -> <gdb:type> */
>  
>  static SCM
> @@ -1351,6 +1369,11 @@ For example, for a value which is a reference to an 'int' pointer ('int *'),\n\
>  value-dereference will result in a value of type 'int' while\n\
>  value-referenced-value will result in a value of type 'int *'." },
>  
> +  { "value-reference-value", 1, 0, 0,
> +    as_a_scm_t_subr (gdbscm_value_reference_value),
> +    "\
> +Return a <gdb:value> object which is a reference to the given value." },
> +
>    { "value-field", 2, 0, 0, as_a_scm_t_subr (gdbscm_value_field),
>      "\
>  Return the specified field of the value.\n\
> diff --git a/gdb/testsuite/gdb.guile/scm-value.exp b/gdb/testsuite/gdb.guile/scm-value.exp
> index 191af1d71a6..83399f32103 100644
> --- a/gdb/testsuite/gdb.guile/scm-value.exp
> +++ b/gdb/testsuite/gdb.guile/scm-value.exp
> @@ -173,6 +173,9 @@ proc test_value_in_inferior {} {
>  	"get string beyond null"
>      gdb_test "gu (print nullst)" \
>  	"= divide\\\\000et"
> +
> +    gdb_test "gu (equal? argv (value-referenced-value (value-reference-value argv)))" \
> +	"#t"
>  }
>  
>  proc test_strings {} {
> -- 
> 2.30.2