PR python/18285

gdb/ChangeLog:

	PR python/18285
	* NEWS: Document new gdb.XMethodWorker.get_result_type method.
	* eval.c (evaluate_subexp_standard) <OP_FUNCALL>: Handle
	EVAL_AVOID_SIDE_EFFECTS for xmethods.
	* extension-priv.h (struct extension_language_ops)
	<get_xmethod_result_type>: New member.
	* extension.c (get_xmethod_result_type): New function.
	* extension.h (get_xmethod_result_type): Declare.
	* python/py-xmethods.c (get_result_type_method_name): New static
	global.
	(py_get_result_type_method_name): Ditto.
	(gdbpy_get_xmethod_result_type): New function.
	(gdbpy_initialize_xmethods): Initialize py_get_result_type_method_name.
	* python/python-internal.h (gdbpy_get_xmethod_result_type): Declare.
	* python/python.c (python_extension_ops): Add
	gdbpy_get_xmethod_result_type.
	* python/lib/gdb/xmethod.py (XMethodWorker): Add get_result_type.
	* valarith.c (value_x_binop): Handle EVAL_AVOID_SIDE_EFFECTS for
	xmethods.
	(value_x_unop): Ditto.
	* value.c (result_type_of_xmethod): New function.
	* value.h (result_type_of_xmethod): Declare.

gdb/testsuite/ChangeLog:

	* gdb.python/py-xmethods.exp: Add ptype tests.
	* gdb.python/py-xmethods.py (E_method_char_worker): Add
	get_result_type method.

gdb/doc/ChangeLog:

	* python.texi (Xmethod API) <gdb.XMethodWorker.get_result_type>:
	Document.
	(Writing an Xmethod): Add get_result_type to example.

2 files changed, 16 insertions, 2 deletions

diff --git a/gdb/testsuite/gdb.python/py-xmethods.exp b/gdb/testsuite/gdb.python/py-xmethods.exp
index a83b14d..eea1283 100644
--- a/gdb/testsuite/gdb.python/py-xmethods.exp
+++ b/gdb/testsuite/gdb.python/py-xmethods.exp
@@ -107,8 +107,9 @@ gdb_test "p a_ptr->geta()" "From Python <A_geta>.*30" "After: a_ptr->geta()"
 gdb_test "p e.geta()" "From Python <A_geta>.*100" "After: e.geta()"
 gdb_test "p e_ptr->geta()" "From Python <A_geta>.*100" "After: e_ptr->geta()"
 gdb_test "p e_ref.geta()" "From Python <A_geta>.*100" "After: e_ref.geta()"
-gdb_test "p e.method(10)" "From Python <E_method_int>.*" "After: e.method(10)"
-gdb_test "p e.method('a')" "From Python <E_method_char>.*" \
+gdb_test "p e.method(10)" "From Python <E_method_int>.* = void" \
+  "After: e.method(10)"
+gdb_test "p e.method('a')" "From Python <E_method_char>.* = void" \
   "After: e.method('a')"
 gdb_test "p g.size_diff<float>  ()" "From Python G<>::size_diff.*" \
   "After: g.size_diff<float>()"
@@ -149,3 +150,11 @@ gdb_test_no_output "disable xmethod progspace E_methods;method_int" \
   "disable xmethod progspace E_methods;method_int"
 gdb_test "info xmethod progspace E_methods;method_int" ".* \\\[disabled\\\]" \
   "info xmethod xmethods E_methods;method_int"
+
+# PR 18285
+# First make sure both are enabled.
+gdb_test_no_output "enable xmethod progspace E_methods;method_char"
+gdb_test_no_output "enable xmethod progspace E_methods;method_int"
+gdb_test "pt e.method('a')" "type = void"
+gdb_test "pt e.method(10)" \
+    "NotImplementedError.*Error while fetching result type of an xmethod worker defined in Python."
diff --git a/gdb/testsuite/gdb.python/py-xmethods.py b/gdb/testsuite/gdb.python/py-xmethods.py
index 78935e1..3a2f100 100644
--- a/gdb/testsuite/gdb.python/py-xmethods.py
+++ b/gdb/testsuite/gdb.python/py-xmethods.py
@@ -60,6 +60,9 @@ class E_method_char_worker(XMethodWorker):
     def get_arg_types(self):
         return gdb.lookup_type('char')
 
+    def get_result_type(self, obj, arg):
+        return gdb.lookup_type('void')
+
     def __call__(self, obj, arg):
         print('From Python <E_method_char>')
         return None
@@ -72,6 +75,8 @@ class E_method_int_worker(XMethodWorker):
     def get_arg_types(self):
         return gdb.lookup_type('int')
 
+    # Note: get_result_type method elided on purpose
+
     def __call__(self, obj, arg):
         print('From Python <E_method_int>')
         return None