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

[George Barrett]

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.

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