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RFC: fix PR c++/8888
- From: Tom Tromey <tromey at redhat dot com>
- To: gdb-patches at sourceware dot org
- Date: Wed, 21 Nov 2012 14:30:18 -0700
- Subject: RFC: fix PR c++/8888
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"