[PATCH] fix PR 17106

[Tom Tromey <tromey at redhat dot com>]

This fixes PR 17106, a regression in printing.

The bug is that resolve_dynamic_type follows struct members and
references, but doesn't consider the possibility of infinite
recursion.

This patch fixes the problem by limiting reference following to the
topmost layer of calls -- that is, reference-typed struct members are
never considered as being VLAs.

Built and regtested on x86-64 Fedora 20.
New test case included.

2014-07-03  Tom Tromey  <tromey@redhat.com>

	PR exp/17106:
	* gdbtypes.c (is_dynamic_type_internal): New function, from
	is_dynamic_type.
	(is_dynamic_type): Rewrite.
	(resolve_dynamic_union): Use resolve_dynamic_type_internal.
	(resolve_dynamic_struct): Likewise.
	(resolve_dynamic_type_internal): New function, from
	resolve_dynamic_type.
	(resolve_dynamic_type): Rewrite.

2014-07-03  Tom Tromey  <tromey@redhat.com>

	* gdb.cp/vla-cxx.cc: New file.
	* gdb.cp/vla-cxx.exp: New file.
---
 gdb/ChangeLog                    | 12 +++++++++
 gdb/gdbtypes.c                   | 56 +++++++++++++++++++++++++++++-----------
 gdb/testsuite/ChangeLog          |  5 ++++
 gdb/testsuite/gdb.cp/vla-cxx.cc  | 49 +++++++++++++++++++++++++++++++++++
 gdb/testsuite/gdb.cp/vla-cxx.exp | 35 +++++++++++++++++++++++++
 5 files changed, 142 insertions(+), 15 deletions(-)
 create mode 100644 gdb/testsuite/gdb.cp/vla-cxx.cc
 create mode 100644 gdb/testsuite/gdb.cp/vla-cxx.exp

diff --git a/gdb/gdbtypes.c b/gdb/gdbtypes.c
index d0c002f..e99a2f3 100644
--- a/gdb/gdbtypes.c
+++ b/gdb/gdbtypes.c
@@ -1611,14 +1611,15 @@ stub_noname_complaint (void)
   complaint (&symfile_complaints, _("stub type has NULL name"));
 }
 
-/* See gdbtypes.h.  */
+/* Worker for is_dynamic_type.  */
 
-int
-is_dynamic_type (struct type *type)
+static int
+is_dynamic_type_internal (struct type *type, int top_level)
 {
   type = check_typedef (type);
 
-  if (TYPE_CODE (type) == TYPE_CODE_REF)
+  /* We only want to recognize references at the outermost level.  */
+  if (top_level && TYPE_CODE (type) == TYPE_CODE_REF)
     type = check_typedef (TYPE_TARGET_TYPE (type));
 
   switch (TYPE_CODE (type))
@@ -1632,9 +1633,9 @@ is_dynamic_type (struct type *type)
 
 	/* The array is dynamic if either the bounds are dynamic,
 	   or the elements it contains have a dynamic contents.  */
-	if (is_dynamic_type (TYPE_INDEX_TYPE (type)))
+	if (is_dynamic_type_internal (TYPE_INDEX_TYPE (type), 0))
 	  return 1;
-	return is_dynamic_type (TYPE_TARGET_TYPE (type));
+	return is_dynamic_type_internal (TYPE_TARGET_TYPE (type), 0);
       }
 
     case TYPE_CODE_STRUCT:
@@ -1644,7 +1645,7 @@ is_dynamic_type (struct type *type)
 
 	for (i = 0; i < TYPE_NFIELDS (type); ++i)
 	  if (!field_is_static (&TYPE_FIELD (type, i))
-	      && is_dynamic_type (TYPE_FIELD_TYPE (type, i)))
+	      && is_dynamic_type_internal (TYPE_FIELD_TYPE (type, i), 0))
 	    return 1;
       }
       break;
@@ -1653,6 +1654,18 @@ is_dynamic_type (struct type *type)
   return 0;
 }
 
+/* See gdbtypes.h.  */
+
+int
+is_dynamic_type (struct type *type)
+{
+  return is_dynamic_type_internal (type, 1);
+}
+
+static struct type *resolve_dynamic_type_internal (struct type *type,
+						   CORE_ADDR addr,
+						   int top_level);
+
 /* Given a dynamic range type (dyn_range_type), return a static version
    of that type.  */
 
@@ -1758,7 +1771,8 @@ resolve_dynamic_union (struct type *type, CORE_ADDR addr)
       if (field_is_static (&TYPE_FIELD (type, i)))
 	continue;
 
-      t = resolve_dynamic_type (TYPE_FIELD_TYPE (resolved_type, i), addr);
+      t = resolve_dynamic_type_internal (TYPE_FIELD_TYPE (resolved_type, i),
+					 addr, 0);
       TYPE_FIELD_TYPE (resolved_type, i) = t;
       if (TYPE_LENGTH (t) > max_len)
 	max_len = TYPE_LENGTH (t);
@@ -1795,7 +1809,8 @@ resolve_dynamic_struct (struct type *type, CORE_ADDR addr)
       if (field_is_static (&TYPE_FIELD (type, i)))
 	continue;
 
-      t = resolve_dynamic_type (TYPE_FIELD_TYPE (resolved_type, i), addr);
+      t = resolve_dynamic_type_internal (TYPE_FIELD_TYPE (resolved_type, i),
+					 addr, 0);
 
       /* This is a bit odd.  We do not support a VLA in any position
 	 of a struct except for the last.  GCC does have an extension
@@ -1823,15 +1838,16 @@ resolve_dynamic_struct (struct type *type, CORE_ADDR addr)
   return resolved_type;
 }
 
-/* See gdbtypes.h  */
+/* Worker for resolved_dynamic_type.  */
 
-struct type *
-resolve_dynamic_type (struct type *type, CORE_ADDR addr)
+static struct type *
+resolve_dynamic_type_internal (struct type *type, CORE_ADDR addr,
+			       int top_level)
 {
   struct type *real_type = check_typedef (type);
   struct type *resolved_type = type;
 
-  if (!is_dynamic_type (real_type))
+  if (!is_dynamic_type_internal (real_type, top_level))
     return type;
 
   switch (TYPE_CODE (type))
@@ -1839,7 +1855,8 @@ resolve_dynamic_type (struct type *type, CORE_ADDR addr)
       case TYPE_CODE_TYPEDEF:
 	resolved_type = copy_type (type);
 	TYPE_TARGET_TYPE (resolved_type)
-	  = resolve_dynamic_type (TYPE_TARGET_TYPE (type), addr);
+	  = resolve_dynamic_type_internal (TYPE_TARGET_TYPE (type), addr,
+					   top_level);
 	break;
 
       case TYPE_CODE_REF:
@@ -1848,7 +1865,8 @@ resolve_dynamic_type (struct type *type, CORE_ADDR addr)
 
 	  resolved_type = copy_type (type);
 	  TYPE_TARGET_TYPE (resolved_type)
-	    = resolve_dynamic_type (TYPE_TARGET_TYPE (type), target_addr);
+	    = resolve_dynamic_type_internal (TYPE_TARGET_TYPE (type),
+					     target_addr, top_level);
 	  break;
 	}
 
@@ -1872,6 +1890,14 @@ resolve_dynamic_type (struct type *type, CORE_ADDR addr)
   return resolved_type;
 }
 
+/* See gdbtypes.h  */
+
+struct type *
+resolve_dynamic_type (struct type *type, CORE_ADDR addr)
+{
+  return resolve_dynamic_type_internal (type, addr, 1);
+}
+
 /* Find the real type of TYPE.  This function returns the real type,
    after removing all layers of typedefs, and completing opaque or stub
    types.  Completion changes the TYPE argument, but stripping of
diff --git a/gdb/testsuite/gdb.cp/vla-cxx.cc b/gdb/testsuite/gdb.cp/vla-cxx.cc
new file mode 100644
index 0000000..ea75df2
--- /dev/null
+++ b/gdb/testsuite/gdb.cp/vla-cxx.cc
@@ -0,0 +1,49 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2014 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/>.  */
+
+struct container;
+
+struct element
+{
+  container &c;
+
+  element(container &cc) : c (cc) { }
+};
+
+struct container
+{
+  element e;
+
+  container() : e(*this) { }
+};
+
+int main(int argc, char **argv)
+{
+  int z = 3;
+  // Note that this is a GNU extension.
+  int vla[z];
+  typeof (vla) &vlaref (vla);
+  typedef typeof (vla) &vlareftypedef;
+  vlareftypedef vlaref2 (vla);
+  container c;
+
+  for (int i = 0; i < z; ++i)
+    vla[i] = 5 + 2 * i;
+
+  // vlas_filled
+  return vla[2];
+}
diff --git a/gdb/testsuite/gdb.cp/vla-cxx.exp b/gdb/testsuite/gdb.cp/vla-cxx.exp
new file mode 100644
index 0000000..1ff815e
--- /dev/null
+++ b/gdb/testsuite/gdb.cp/vla-cxx.exp
@@ -0,0 +1,35 @@
+# Copyright 2014 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/>.
+
+standard_testfile .cc
+
+if { [prepare_for_testing ${testfile}.exp ${testfile} ${srcfile}] } {
+    return -1
+}
+
+if ![runto_main] {
+    return -1
+}
+
+gdb_breakpoint [gdb_get_line_number "vlas_filled"]
+gdb_continue_to_breakpoint "vlas_filled"
+
+gdb_test "print vla" " = \\{5, 7, 9\\}"
+gdb_test "print vlaref" " = \\(int \\(&\\)\\\[3\\\]\\) @$hex: \\{5, 7, 9\\}"
+# The ".*" here is because what gdb emits currently is "const
+# vlareftypedef", which seems incorrect -- and since that isn't the
+# bug being tested, it's better not to depend on the exact spelling.
+gdb_test "print vlaref2" " = \\(.*\\) @$hex: \\{5, 7, 9\\}"
+gdb_test "print c" " = \\{e = \\{c = @$hex\\}\\}"
-- 
1.9.3