Given the following variable...
BT : Bounded := New_Bounded (Low => 1, High => 3);
... where type Bounded is defined as a simple unconstrained array:
type Bounded is array (Integer range <>) of Integer;
Creating a varobj for that variable, and immediately asking for
varobj updates, GDB says that our varobj changed types!
(gdb)
-var-create bt * bt
^done,name="bt",numchild="3",value="[3]",type="<ref> array (1 .. 3) of integer",has_more="0"
(gdb)
-var-update 1 *
^done,changelist=[{name="bt",value="[3]",in_scope="true",type_changed="true",new_type="<ref> array (1 .. 3) of integer",new_num_children="3",has_more="0"}]
The expected output for the -var-update command is, in this case:
(gdb)
-var-update 1 *
^done,changelist=[]
The problem occurs because the ada-varobj module does not handle
references, and while the references gets stripped when the varobj
gets created, it doesn't when computing varobj updates.
More specifically, when creating the varobj, varobj_create creates
a new value which is a reference to a TYPE_CODE_ARRAY. It then calls
install_new_value which calls coerce_ref with the following comment:
/* We are not interested in the address of references, and given
that in C++ a reference is not rebindable, it cannot
meaningfully change. So, get hold of the real value. */
if (value)
value = coerce_ref (value);
This leaves the varobj's type component still a ref, while
the varobj's value is now our array, without the ref. This explains
why the "value" field in the varobj indicates an array with 3 elements
"[3]" while the "type" field shows a ref to an array. Generally
speaking, most users have said that showing the ref was a useful
piece of information, so this patch is not touching this part.
Next, when the user issues the -var-update request, varobj_update
calls value_of_root to compute the varobj's new value as well as
determine whether the value's type has changed or not. What happens
in a nutshell is that it calls value_of_root_1 (which re-evaluates
the expression and returns the corresponding new value), finds that
the new value is not NULL, and thus asks whether it has mutated:
else if (varobj_value_has_mutated (var, value, value_type (value)))
This then indirectly delegates the determination to the language-specific
callback, which fails, because it does not handle references.
This patch fixes the issue by adjusting varobj_value_has_mutated to
expect references, and strip them when seen. This allows the various
language-specific implementations to remain unaware of references.
gdb/ChangeLog:
* varobj.c (varobj_value_has_mutated): If NEW_VALUE is
a reference, strip the reference layer before calling
the lang_ops value_has_mutated callback.
gdb/testsuite/ChangeLog:
* gdb.ada/mi_dyn_arr: New testcase.
+2014-03-28 Joel Brobecker <brobecker@adacore.com>
+
+ * varobj.c (varobj_value_has_mutated): If NEW_VALUE is
+ a reference, strip the reference layer before calling
+ the lang_ops value_has_mutated callback.
+
2014-03-27 Sergio Durigan Junior <sergiodj@redhat.com>
Remove some globals from our parser.
+2014-03-28 Joel Brobecker <brobecker@adacore.com>
+
+ * gdb.ada/mi_dyn_arr: New testcase.
+
2014-03-27 Doug Evans <dje@google.com>
* gdb.dwarf2/dw2-abs-hi-pc.exp: Build tests with "nodebug".
--- /dev/null
+# 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/>.
+
+load_lib "ada.exp"
+
+standard_ada_testfile foo
+
+if {[gdb_compile_ada "${srcfile}" "${binfile}" executable [list debug]] != "" } {
+ return -1
+}
+
+load_lib mi-support.exp
+set MIFLAGS "-i=mi"
+
+gdb_exit
+if [mi_gdb_start] {
+ continue
+}
+
+mi_delete_breakpoints
+mi_gdb_reinitialize_dir $srcdir/$subdir
+mi_gdb_load ${binfile}
+
+if ![mi_run_to_main] then {
+ fail "Cannot run to main, testcase aborted"
+ return 0
+}
+
+set bp_location [gdb_get_line_number "STOP" ${testdir}/foo.adb]
+mi_continue_to_line \
+ "foo.adb:$bp_location" \
+ "stop at start of main Ada procedure"
+
+mi_gdb_test "-var-create bt * bt" \
+ "\\^done,name=\"bt\",numchild=\"3\",.*" \
+ "Create bt varobj"
+
+mi_gdb_test "-var-update 1 *" \
+ "\\^done,changelist=\\\[\\\]" \
+ "list ggg1's children"
--- /dev/null
+-- 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/>.
+
+with Pck; use Pck;
+procedure Foo is
+ -- The goal here is to have an array whose bounds are not
+ -- known at compile time.
+ BT : Bounded := New_Bounded (Low => 1, High => 3);
+begin
+ Do_Nothing (BT'Address); -- STOP
+end Foo;
+
--- /dev/null
+-- 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/>.
+
+package body Pck is
+ function New_Bounded (Low, High : Integer) return Bounded is
+ Result : Bounded (Low .. High);
+ begin
+ for J in Low .. High loop
+ Result (J) := J;
+ end loop;
+ return Result;
+ end New_Bounded;
+
+ procedure Do_Nothing (A : System.Address) is
+ begin
+ null;
+ end Do_Nothing;
+end Pck;
--- /dev/null
+-- 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/>.
+
+with System;
+package Pck is
+ type Bounded is array (Integer range <>) of Integer;
+ function New_Bounded (Low, High : Integer) return Bounded;
+ procedure Do_Nothing (A : System.Address);
+end Pck;
return 0;
if (var->root->lang_ops->value_has_mutated)
- return var->root->lang_ops->value_has_mutated (var, new_value, new_type);
+ {
+ /* The varobj module, when installing new values, explicitly strips
+ references, saying that we're not interested in those addresses.
+ But detection of mutation happens before installing the new
+ value, so our value may be a reference that we need to strip
+ in order to remain consistent. */
+ if (new_value != NULL)
+ new_value = coerce_ref (new_value);
+ return var->root->lang_ops->value_has_mutated (var, new_value, new_type);
+ }
else
return 0;
}
projects / binutils-gdb.git / commitdiff