[PATCH PR gdb/16959] gdb hangs in infinite recursion

[Weimin Pan]

The original problem was fixed (see related PR 22242). But using a typedef
as the declared type for a static member variable, as commented in this PR,
is still causing gdb to get into infinite loop when printing the static
member's value. This problem can be reproduced as follows:

% cat t.cc
class A {
    typedef A type;
public:
    bool operator==(const type& other) { return true; }

    static const type INSTANCE;
};

const A A::INSTANCE;

int main() {
    A a;
    if (a == A::INSTANCE) {
        return -1;
    }
    return 0;
}
% g++ -g t.cc
% gdb -ex "start" -ex "p a" a.out

The fix is rather trivial - in cp_print_static_field(), should call
check_typedef() to get the static member's real type and use it to
check whether it's a struct or an array.

Tested on both aarch64-linux-gnu and amd64-linux-gnu. No regressions.
---
 gdb/ChangeLog     |    7 +++++++
 gdb/cp-valprint.c |    2 +-
 2 files changed, 8 insertions(+), 1 deletions(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index d0a8dfd..6fd43de 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,10 @@
+2018-02-07  Weimin Pan  <weimin.pan@oracle.com>
+
+	PR gdb/16959
+	* cp-valprint.c: (cp_print_static_field) Use check_typedef() to get 
+	static member's real type for TYPE_CODE_STRUCT and TYPE_CODE_ARRAY 
+	comparisons. 
+
 2018-01-24  Pedro Alves  <palves@redhat.com>
 
 	GCC PR libstdc++/83906
diff --git a/gdb/cp-valprint.c b/gdb/cp-valprint.c
index 486653f..0370b56 100644
--- a/gdb/cp-valprint.c
+++ b/gdb/cp-valprint.c
@@ -633,6 +633,7 @@ cp_print_static_field (struct type *type,
       return;
     }
 
+  type = check_typedef (type);
   if (TYPE_CODE (type) == TYPE_CODE_STRUCT)
     {
       CORE_ADDR *first_dont_print;
@@ -658,7 +659,6 @@ cp_print_static_field (struct type *type,
       addr = value_address (val);
       obstack_grow (&dont_print_statmem_obstack, (char *) &addr,
 		    sizeof (CORE_ADDR));
-      type = check_typedef (type);
       cp_print_value_fields (type, value_enclosing_type (val),
 			     value_embedded_offset (val), addr,
 			     stream, recurse, val,
-- 
1.7.1