RFC: fix PR c++/8888

[Tom Tromey <tromey at redhat dot com>]

This patch fixes PR c++/8888.

The bug here is that when gdb is stopped in a method, then references to
the enclosing class name find the constructor rather than the type.
E.g., in the test case in the patch, when stopped in C::m, "print C::x"
will fail.

After investigating the problem for a while, I couldn't find a bad
situation here other than the constructor problem.  So, I made the fix
specific to this case.

There are actually two related failures, but I consider them different
bugs -- in particular I think they need to be fixed in different spots.

First, PR 14819, which I closed as a dup of 8888, but which actually
exhibits two bugs.  This patch partially fixes that PR, but in the PR,
"print C::x" still fails, because this really means "print this->C::x";
but this shorthand isn't implemented in gdb.

Second, you can take the test case from this patch and templatize it.
Then "print C::x" fails, but shouldn't -- but in this case it is because
"C" in this context should refer to the enclosing instance, another
thing that gdb doesn't implement.

I'm going to reopen 14819 and file a new bug for the other problem.

Built and regtested on x86-64 Fedora 16.
New test case included.

Tom

2012-11-21  Tom Tromey  <tromey@redhat.com>

	PR c++/8888:
	* symtab.c (lookup_symbol_aux): If constructor is found, consider
	returning the type instead.
	* c-exp.y (classify_name): Check STRUCT_DOMAIN if no symbol
	found.

2012-11-21  Tom Tromey  <tromey@redhat.com>

	* gdb.cp/member-name.exp: New file.
	* gdb.cp/member-name.cc: New file.

diff --git a/gdb/c-exp.y b/gdb/c-exp.y
index 11eaadb..83175e0 100644
--- a/gdb/c-exp.y
+++ b/gdb/c-exp.y
@@ -2728,6 +2728,32 @@ classify_name (struct block *block)
 	  yylval.bval = BLOCKVECTOR_BLOCK (BLOCKVECTOR (symtab), STATIC_BLOCK);
 	  return FILENAME;
 	}
+
+      /* If we found a field of 'this', we might have erroneously
+	 found a constructor where we wanted a type name.  Handle this
+	 case by noticing that we found a constructor and then look up
+	 the type tag.  */
+      if (is_a_field_of_this)
+	{
+	  unsigned int len;
+	  struct symbol *block_sym = block_containing_function (block);
+	  const char *block_name = SYMBOL_NATURAL_NAME (block_sym);
+
+	  len = cp_entire_prefix_len (block_name);
+	  if (strncmp (block_name, copy, len) == 0)
+	    {
+	      is_a_field_of_this = 0;
+	      sym = lookup_symbol (copy, block, STRUCT_DOMAIN,
+				   &is_a_field_of_this);
+	      if (sym != NULL)
+		{
+		  yylval.tsym.type = SYMBOL_TYPE (sym);
+		  return TYPENAME;
+		}
+	      /* Restore the previous value and keep going.  */
+	      is_a_field_of_this = 1;
+	    }
+	}
     }
 
   if (sym && SYMBOL_CLASS (sym) == LOC_TYPEDEF)
diff --git a/gdb/symtab.c b/gdb/symtab.c
index 05943cf..b429f76 100644
--- a/gdb/symtab.c
+++ b/gdb/symtab.c
@@ -1308,7 +1308,10 @@ lookup_symbol_aux (const char *name, const struct block *block,
 
   langdef = language_def (language);
 
-  if (is_a_field_of_this != NULL)
+  /* Don't do this check if we are searching for a struct.  It will
+     not be found by check_field, but will be found by other
+     means.  */
+  if (is_a_field_of_this != NULL && domain != STRUCT_DOMAIN)
     {
       struct symbol *sym = lookup_language_this (langdef, block);
 
diff --git a/gdb/testsuite/gdb.cp/member-name.cc b/gdb/testsuite/gdb.cp/member-name.cc
new file mode 100644
index 0000000..64afe68
--- /dev/null
+++ b/gdb/testsuite/gdb.cp/member-name.cc
@@ -0,0 +1,51 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2003-2004, 2007-2012 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 C
+{
+  static int x;
+
+  struct inner
+  {
+    static int z;
+  };
+
+  int y;
+
+  C ()
+  {
+    // First breakpoint here
+    y = x + inner::z;
+  }
+
+  int m ()
+  {
+    // Second breakpoint here
+    return x - y;
+  }
+};
+
+int C::x = 23;
+int C::inner::z = 0;
+
+int main ()
+{
+  C c;
+
+  return c.m();
+}
diff --git a/gdb/testsuite/gdb.cp/member-name.exp b/gdb/testsuite/gdb.cp/member-name.exp
new file mode 100644
index 0000000..d4b3740
--- /dev/null
+++ b/gdb/testsuite/gdb.cp/member-name.exp
@@ -0,0 +1,37 @@
+# Copyright 2012 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 {[prepare_for_testing $testfile.exp $testfile $srcfile {debug c++}]} {
+    return -1
+}
+
+if ![runto_main] then {
+    perror "couldn't run to breakpoint"
+    return
+}
+
+gdb_breakpoint ${srcfile}:[gdb_get_line_number "First breakpoint"]
+gdb_continue_to_breakpoint "continue to first breakpoint"
+gdb_test "print C::x" " = 23" "print C::x from first breakpoint"
+gdb_test "print inner::z" " = 0" "print inner::z from first breakpoint"
+
+gdb_breakpoint ${srcfile}:[gdb_get_line_number "Second breakpoint"]
+gdb_continue_to_breakpoint "continue to second breakpoint"
+gdb_test "print C::x" " = 23" "print C::x from second breakpoint"
+gdb_test "print inner::z" " = 0" "print inner::z from second breakpoint"