Use bitpos and type to lookup a gdb.Field object when its name is 'None'.

PR python/15464
	PR python/16113
	* valops.c (value_struct_elt_bitpos): New function
	* py-type.c (convert_field): Set 'name' attribute of a gdb.Field
	object to 'None' if the field name is an empty string ("").
	* python/py-value.c (valpy_getitem): Use 'bitpos' and 'type'
	attribute to look for a field when 'name' is 'None'.
	(get_field_type): New function

	testsuite/
	* gdb.python/py-type.c: Enhance test case.
	* gdb.python/py-value-cc.cc: Likewise
	* gdb.python/py-type.exp: Add new tests.
	* gdb.python/py-value-cc.exp: Likewise

gdb/testsuite/gdb.python/py-type.c

@@ -21,6 +21,12 @@ struct s
   int b;
 };
 
+struct SS
+{
+  union { int x; char y; };
+  union { int a; char b; };
+};
+
 typedef struct s TS;
 TS ts;
 
@@ -58,6 +64,7 @@ main ()
 {
   int ar[2] = {1,2};
   struct s st;
+  struct SS ss;
 #ifdef __cplusplus
   C c;
   c.c = 1;
@@ -72,6 +79,8 @@ main ()
   st.b = 5;
 
   e = v2;
+
+  ss.x = 100;
   
   return 0;      /* break to inspect struct and array.  */
 }

gdb/testsuite/gdb.python/py-type.exp

@@ -85,6 +85,15 @@ proc test_fields {lang} {
     gdb_test "python print (fields\[0\].name)" "a" "Check structure field a name"
     gdb_test "python print (fields\[1\].name)" "b" "Check structure field b name"
 
+    # Test that unamed fields have 'None' for name.
+    gdb_py_test_silent_cmd "python ss = gdb.parse_and_eval('ss')" "init ss" 1
+    gdb_py_test_silent_cmd "python ss_fields = ss.type.fields()" \
+      "get fields from ss.type" 1
+    gdb_test "python print len(ss_fields)" "2" "Check length of ss_fields"
+    gdb_test "python print ss_fields\[0\].name is None" "True" \
+      "Check ss_fields\[0\].name"
+    gdb_test "python print ss_fields\[1\].name is None" "True" \
+      "Check ss_fields\[1\].name"
     # Regression test for
     # http://sourceware.org/bugzilla/show_bug.cgi?id=12070.
     gdb_test "python print ('type' in dir(fields\[0\]))" "True" \

gdb/testsuite/gdb.python/py-value-cc.cc

@@ -30,8 +30,21 @@ class B : public A {
   char a;
 };
 
+struct X
+{
+  union { int x; char y; };
+  union { int a; char b; };
+};
+
+union UU
+{
+  union { int x; char y; };
+  union { int a; char b; };
+};
+
 typedef B Btd;
 typedef int *int_ptr;
+typedef X Xtd;
 
 int
 func (const A &a)
@@ -57,6 +70,16 @@ func (const A &a)
   U u;
   u.a = 99;
 
+  X x;
+  x.x = 101;
+  x.a = 102;
+
+  UU uu;
+  uu.x = 1000;
+
+  X *x_ptr = &x;
+  Xtd *xtd = &x;
+
   return 0; /* Break here.  */
 }
 

gdb/testsuite/gdb.python/py-value-cc.exp

@@ -53,6 +53,14 @@ gdb_test_no_output "python b_ref = gdb.parse_and_eval('b_ref')" "init b_ref"
 gdb_test_no_output "python b_td = gdb.parse_and_eval('b_td')" "init b_td"
 gdb_test_no_output "python u = gdb.parse_and_eval('u')" "init u"
 gdb_test_no_output "python u_fields = u.type.fields()" "init u_fields"
+gdb_test_no_output "python x = gdb.parse_and_eval('x')" "init x"
+gdb_test_no_output "python x_fields = x.type.fields()" "init x_fields"
+gdb_test_no_output "python uu = gdb.parse_and_eval('uu')" "init uu"
+gdb_test_no_output "python uu_fields = uu.type.fields()" "init uu_fields"
+gdb_test_no_output "python x_ptr = gdb.parse_and_eval('x_ptr')" "init x_ptr"
+gdb_test_no_output "python xtd = gdb.parse_and_eval('xtd')" "init xtd"
+
+gdb_test "python print(b\[b_fields\[1\]\])" "97 'a'" "b.a via field"
 
 gdb_test "python print(b\[b_fields\[1\]\])" "97 'a'" "b.a via field"
 gdb_test "python print(b\[b_fields\[0\]\].type)" "A" \
@@ -79,3 +87,15 @@ gdb_test "python print(b_td\[b_fields\[0\]\]\['a'\])" "100" \
 
 gdb_test "python print(u\[u_fields\[0\]\])" "99.*" "u's first field via field"
 gdb_test "python print(u\[u_fields\[1\]\])" "99.*" "u's second field via field"
+
+gdb_test "python print len(x_fields)" "2" "number for fields in u"
+gdb_test "python print x\[x_fields\[0\]\]\['x'\]" "101" "x.x via field"
+gdb_test "python print x\[x_fields\[1\]\]\['a'\]" "102" "x.a via field"
+gdb_test "python print x_ptr\[x_fields\[0\]\]\['x'\]" "101" "x_ptr->x via field"
+gdb_test "python print x_ptr\[x_fields\[1\]\]\['a'\]" "102" "x_ptr->a via field"
+gdb_test "python print xtd\[x_fields\[0\]\]\['x'\]" "101" "xtd->x via field"
+gdb_test "python print xtd\[x_fields\[1\]\]\['a'\]" "102" "xtd->a via field"
+
+gdb_test "python print len(uu_fields)" "2" "number of fields in uu"
+gdb_test "python print uu\[uu_fields\[0\]\]\['x'\]" "1000" "uu.x via field"
+gdb_test "python print uu\[uu_fields\[1\]\]\['a'\]" "1000" "uu.a via field"