[varobj] false type-changed status for reference to Ada array
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.
This commit is contained in:
parent
acd6540d35
commit
8776cfe971
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@ -1,3 +1,9 @@
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2014-03-28 Joel Brobecker <brobecker@adacore.com>
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* varobj.c (varobj_value_has_mutated): If NEW_VALUE is
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a reference, strip the reference layer before calling
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the lang_ops value_has_mutated callback.
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2014-03-27 Sergio Durigan Junior <sergiodj@redhat.com>
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Remove some globals from our parser.
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@ -1,3 +1,7 @@
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2014-03-28 Joel Brobecker <brobecker@adacore.com>
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* gdb.ada/mi_dyn_arr: New testcase.
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2014-03-27 Doug Evans <dje@google.com>
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* gdb.dwarf2/dw2-abs-hi-pc.exp: Build tests with "nodebug".
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@ -0,0 +1,52 @@
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# Copyright 2014 Free Software Foundation, Inc.
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 3 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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load_lib "ada.exp"
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standard_ada_testfile foo
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if {[gdb_compile_ada "${srcfile}" "${binfile}" executable [list debug]] != "" } {
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return -1
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}
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load_lib mi-support.exp
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set MIFLAGS "-i=mi"
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gdb_exit
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if [mi_gdb_start] {
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continue
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}
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mi_delete_breakpoints
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mi_gdb_reinitialize_dir $srcdir/$subdir
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mi_gdb_load ${binfile}
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if ![mi_run_to_main] then {
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fail "Cannot run to main, testcase aborted"
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return 0
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}
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set bp_location [gdb_get_line_number "STOP" ${testdir}/foo.adb]
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mi_continue_to_line \
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"foo.adb:$bp_location" \
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"stop at start of main Ada procedure"
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mi_gdb_test "-var-create bt * bt" \
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"\\^done,name=\"bt\",numchild=\"3\",.*" \
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"Create bt varobj"
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mi_gdb_test "-var-update 1 *" \
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"\\^done,changelist=\\\[\\\]" \
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"list ggg1's children"
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@ -0,0 +1,24 @@
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-- Copyright 2014 Free Software Foundation, Inc.
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--
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-- This program is free software; you can redistribute it and/or modify
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-- it under the terms of the GNU General Public License as published by
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-- the Free Software Foundation; either version 3 of the License, or
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-- (at your option) any later version.
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--
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-- This program is distributed in the hope that it will be useful,
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-- but WITHOUT ANY WARRANTY; without even the implied warranty of
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-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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-- GNU General Public License for more details.
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--
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-- You should have received a copy of the GNU General Public License
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-- along with this program. If not, see <http://www.gnu.org/licenses/>.
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with Pck; use Pck;
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procedure Foo is
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-- The goal here is to have an array whose bounds are not
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-- known at compile time.
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BT : Bounded := New_Bounded (Low => 1, High => 3);
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begin
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Do_Nothing (BT'Address); -- STOP
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end Foo;
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-- Copyright 2014 Free Software Foundation, Inc.
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--
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-- This program is free software; you can redistribute it and/or modify
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-- it under the terms of the GNU General Public License as published by
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-- the Free Software Foundation; either version 3 of the License, or
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-- (at your option) any later version.
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--
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-- This program is distributed in the hope that it will be useful,
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-- but WITHOUT ANY WARRANTY; without even the implied warranty of
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-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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-- GNU General Public License for more details.
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--
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-- You should have received a copy of the GNU General Public License
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-- along with this program. If not, see <http://www.gnu.org/licenses/>.
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package body Pck is
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function New_Bounded (Low, High : Integer) return Bounded is
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Result : Bounded (Low .. High);
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begin
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for J in Low .. High loop
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Result (J) := J;
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end loop;
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return Result;
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end New_Bounded;
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procedure Do_Nothing (A : System.Address) is
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begin
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null;
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end Do_Nothing;
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end Pck;
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@ -0,0 +1,21 @@
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-- Copyright 2014 Free Software Foundation, Inc.
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--
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-- This program is free software; you can redistribute it and/or modify
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-- it under the terms of the GNU General Public License as published by
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-- the Free Software Foundation; either version 3 of the License, or
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-- (at your option) any later version.
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--
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-- This program is distributed in the hope that it will be useful,
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-- but WITHOUT ANY WARRANTY; without even the implied warranty of
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-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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-- GNU General Public License for more details.
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--
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-- You should have received a copy of the GNU General Public License
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-- along with this program. If not, see <http://www.gnu.org/licenses/>.
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with System;
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package Pck is
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type Bounded is array (Integer range <>) of Integer;
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function New_Bounded (Low, High : Integer) return Bounded;
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procedure Do_Nothing (A : System.Address);
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end Pck;
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11
gdb/varobj.c
11
gdb/varobj.c
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@ -1649,7 +1649,16 @@ varobj_value_has_mutated (struct varobj *var, struct value *new_value,
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return 0;
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if (var->root->lang_ops->value_has_mutated)
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return var->root->lang_ops->value_has_mutated (var, new_value, new_type);
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{
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/* The varobj module, when installing new values, explicitly strips
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references, saying that we're not interested in those addresses.
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But detection of mutation happens before installing the new
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value, so our value may be a reference that we need to strip
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in order to remain consistent. */
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if (new_value != NULL)
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new_value = coerce_ref (new_value);
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return var->root->lang_ops->value_has_mutated (var, new_value, new_type);
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}
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else
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return 0;
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}
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