[PATCH 4 PR gdb/16959] gdb hangs in infinite recursion

[Weimin Pan <weimin dot pan at oracle dot com>]

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.

As Simon suggested, I've added a new test case to the testsuite
and am passing the original type, not the real type, as argument
to function val_print().

Re-tested on both aarch64-linux-gnu and amd64-linux-gnu. No regressions.
---
 gdb/ChangeLog                                 |    6 ++++
 gdb/cp-valprint.c                             |    8 +++---
 gdb/testsuite/ChangeLog                       |    5 +++
 gdb/testsuite/gdb.cp/static-typedef-print.cc  |   34 +++++++++++++++++++++++
 gdb/testsuite/gdb.cp/static-typedef-print.exp |   37 +++++++++++++++++++++++++
 5 files changed, 86 insertions(+), 4 deletions(-)
 create mode 100644 gdb/testsuite/gdb.cp/static-typedef-print.cc
 create mode 100644 gdb/testsuite/gdb.cp/static-typedef-print.exp

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index d0a8dfd..9534225 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,9 @@
+2018-02-07  Weimin Pan  <weimin.pan@oracle.com>
+
+	PR gdb/16959
+	* cp-valprint.c: (cp_print_static_field) Fix infinite recursion when
+	printing static type.
+
 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..8b4df98 100644
--- a/gdb/cp-valprint.c
+++ b/gdb/cp-valprint.c
@@ -633,7 +633,8 @@ cp_print_static_field (struct type *type,
       return;
     }
 
-  if (TYPE_CODE (type) == TYPE_CODE_STRUCT)
+  struct type *real_type = check_typedef (type);
+  if (TYPE_CODE (real_type) == TYPE_CODE_STRUCT)
     {
       CORE_ADDR *first_dont_print;
       CORE_ADDR addr;
@@ -658,15 +659,14 @@ 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),
+      cp_print_value_fields (real_type, value_enclosing_type (val),
 			     value_embedded_offset (val), addr,
 			     stream, recurse, val,
 			     options, NULL, 1);
       return;
     }
 
-  if (TYPE_CODE (type) == TYPE_CODE_ARRAY)
+  if (TYPE_CODE (real_type) == TYPE_CODE_ARRAY)
     {
       struct type **first_dont_print;
       int i;
diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 0f02f4a..6849d5a 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2018-03-20  Weimin Pan  <weimin.pan@oracle.com>
+
+	* gdb.cp/static-typedef-print.exp: New file.
+	* gdb.cp/static-typedef-print.cc: New file.
+
 2018-01-22  Pedro Alves  <palves@redhat.com>
 	    Sergio Durigan Junior  <sergiodj@redhat.com>
 
diff --git a/gdb/testsuite/gdb.cp/static-typedef-print.cc b/gdb/testsuite/gdb.cp/static-typedef-print.cc
new file mode 100644
index 0000000..5faff3e
--- /dev/null
+++ b/gdb/testsuite/gdb.cp/static-typedef-print.cc
@@ -0,0 +1,34 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2018 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+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;
+}
diff --git a/gdb/testsuite/gdb.cp/static-typedef-print.exp b/gdb/testsuite/gdb.cp/static-typedef-print.exp
new file mode 100644
index 0000000..ff6756e
--- /dev/null
+++ b/gdb/testsuite/gdb.cp/static-typedef-print.exp
@@ -0,0 +1,37 @@
+# Copyright 2018 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+if { [skip_cplus_tests] } { continue }
+
+standard_testfile .cc
+
+if [get_compiler_info "c++"] {
+    return -1
+}
+
+if {[prepare_for_testing "failed to prepare" $testfile $srcfile {debug c++}]} {
+    return -1
+}
+
+clean_restart $testfile
+
+if ![runto_main] {
+    untested "could not run to main"
+    return -1
+}
+
+gdb_test "print a" \
+         "static INSTANCE = <same as static member of an already seen type>}}.*" \
+         "print static member"
-- 
1.7.1