Fix accessing a function's fields (parameters) from Python (PR 18073)

Since 7.4, gdb doesn't allow calling .fields() on a function type, even
though the documentation states it should return a list corresponding to
the function's parameters.  This patch restores the intended behaviour
and adds a test for it.

Reg-tested on Arch Linux x86-64.

gdb/ChangeLog:

	PR python/18073
	* python/py-type.c (typy_get_composite): Allow returning a
	function type.

gdb/testsuite/ChangeLog:

	PR python/18073
	* gdb.python/py-type.c (C::a_method): New.
	(C::a_const_method): New.
	(C::a_static_method): New.
	(a_function): New.
	* gdb.python/py-type.exp (test_fields): Test getting fields
	from function and method.

2 files changed, 56 insertions, 6 deletions

diff --git a/gdb/testsuite/gdb.python/py-type.c b/gdb/testsuite/gdb.python/py-type.c
index e3901cc..36ce1d8 100644
--- a/gdb/testsuite/gdb.python/py-type.c
+++ b/gdb/testsuite/gdb.python/py-type.c
@@ -35,6 +35,24 @@ struct C
 {
   int c;
   int d;
+
+  int
+  a_method (int x, char y)
+    {
+      return x + y;
+    }
+
+  int
+  a_const_method (int x, char y) const
+    {
+      return x + y;
+    }
+
+  static int
+  a_static_method (int x, char y)
+    {
+      return x + y;
+    }
 };
 
 struct D : C
@@ -59,6 +77,12 @@ enum E
 struct s vec_data_1 = {1, 1};
 struct s vec_data_2 = {1, 2};
 
+static int
+a_function (int x, char y)
+{
+  return x + y;
+}
+
 int
 main ()
 {
@@ -72,15 +96,21 @@ main ()
   D d;
   d.e = 3;
   d.f = 4;
+
+  c.a_method (0, 1);
+  c.a_const_method (0, 1);
+  C::a_static_method (0, 1);
 #endif
   enum E e;
-  
+
   st.a = 3;
   st.b = 5;
 
   e = v2;
 
   ss.x = 100;
-  
+
+  a_function (0, 1);
+
   return 0;      /* break to inspect struct and array.  */
 }
diff --git a/gdb/testsuite/gdb.python/py-type.exp b/gdb/testsuite/gdb.python/py-type.exp
index ce6edde..10decee 100644
--- a/gdb/testsuite/gdb.python/py-type.exp
+++ b/gdb/testsuite/gdb.python/py-type.exp
@@ -77,6 +77,21 @@ proc test_fields {lang} {
       gdb_test "python print (c.type == gdb.parse_and_eval('d').type)" "False"
       gdb_test "python print (c.type == gdb.parse_and_eval('d').type.fields()\[0\].type)" \
 	  "True"
+
+      # Test fields of a method (its parameters)
+      gdb_test "python print (len (gdb.parse_and_eval ('C::a_method').type.fields ()))" "3"
+      gdb_test "python print (gdb.parse_and_eval ('C::a_method').type.fields ()\[0\].type)" "C \\* const"
+      gdb_test "python print (gdb.parse_and_eval ('C::a_method').type.fields ()\[1\].type)" "int"
+      gdb_test "python print (gdb.parse_and_eval ('C::a_method').type.fields ()\[2\].type)" "char"
+
+      gdb_test "python print (len (gdb.parse_and_eval ('C::a_const_method').type.fields ()))" "3"
+      gdb_test "python print (gdb.parse_and_eval ('C::a_const_method').type.fields ()\[0\].type)" "const C \\* const"
+      gdb_test "python print (gdb.parse_and_eval ('C::a_const_method').type.fields ()\[1\].type)" "int"
+      gdb_test "python print (gdb.parse_and_eval ('C::a_const_method').type.fields ()\[2\].type)" "char"
+
+      gdb_test "python print (len (gdb.parse_and_eval ('C::a_static_method').type.fields ()))" "2"
+      gdb_test "python print (gdb.parse_and_eval ('C::a_static_method').type.fields ()\[0\].type)" "int"
+      gdb_test "python print (gdb.parse_and_eval ('C::a_static_method').type.fields ()\[1\].type)" "char"
     }
 
     # Test normal fields usage in structs.
@@ -111,10 +126,10 @@ proc test_fields {lang} {
     gdb_test "python print (not not st.type)" "True" "Check conversion to bool"
 
     # Test rejection of mapping operations on scalar types
-    gdb_test "python print (len (st.type\['a'\].type))" "TypeError: Type is not a structure, union, or enum type.*"
-    gdb_test "python print (st.type\['a'\].type.has_key ('x'))" "TypeError: Type is not a structure, union, or enum type.*"
-    gdb_test "python print (st.type\['a'\].type.keys ())" "TypeError: Type is not a structure, union, or enum type.*"
-    gdb_test "python print (st.type\['a'\].type\['x'\])" "TypeError: Type is not a structure, union, or enum type.*"
+    gdb_test "python print (len (st.type\['a'\].type))" "TypeError: Type is not a structure, union, enum, or function type.*"
+    gdb_test "python print (st.type\['a'\].type.has_key ('x'))" "TypeError: Type is not a structure, union, enum, or function type.*"
+    gdb_test "python print (st.type\['a'\].type\['x'\])" "TypeError: Type is not a structure, union, enum, or function type.*"
+    gdb_test "python print (st.type\['a'\].type.keys ())" "TypeError: Type is not a structure, union, enum, or function type.*"
 
     # Test conversion to bool on scalar types
     gdb_test "python print (not not st.type\['a'\].type)" "True"
@@ -150,6 +165,11 @@ proc test_fields {lang} {
     gdb_test "python print (vec1 == vec2)" "True"
     gdb_py_test_silent_cmd "python vec3 = vec_data_2.cast(ar\[0\].type.vector(1))" "set vec3" 1
     gdb_test "python print (vec1 == vec3)" "False"
+
+    # Test fields of a function (its parameters)
+    gdb_test "python print (len (gdb.parse_and_eval ('a_function').type.fields ()))" "2"
+    gdb_test "python print (gdb.parse_and_eval ('a_function').type.fields ()\[0\].type)" "int"
+    gdb_test "python print (gdb.parse_and_eval ('a_function').type.fields ()\[1\].type)" "char"
   }
 }