d391f3721e
It's currently not possible to cast an in-memory value of a primitive
type to const reference:
```
(gdb) p Q.id
$1 = 42
(gdb) p (int&)Q.id
$2 = (int &) @0x22fd0c: 42
(gdb) p (const int&)Q.id
Attempt to take address of value not located in memory.
```
And if in a function call an argument needs the same kind of casting,
it also doesn't work:
```
(gdb) l f3
39 int f3(const int &i)
40 {
41 return i;
42 }
(gdb) p f3(Q.id)
Attempt to take address of value not located in memory.
```
It's because when the constness of the type changes in a call to
value_cast, a new not_lval value is allocated, which doesn't exist
in the target memory.
Fixed by ignoring const/volatile/restrict qualifications in
value_cast when comparing cast type to original type, so the new
value will point to the same location as the original value:
```
(gdb) p (int&)i
$2 = (int &) @0x39f72c: 1
(gdb) p (const int&)i
$3 = (const int &) @0x39f72c: 1
(gdb) p f3(Q.id)
$4 = 42
```
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=19423
Approved-By: Tom Tromey <tom@tromey.com>
80 lines
1.6 KiB
C++
80 lines
1.6 KiB
C++
/* This test script is part of GDB, the GNU debugger.
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Copyright 2006-2024 Free Software Foundation, Inc.
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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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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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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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/* Author: Paul N. Hilfinger, AdaCore Inc. */
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struct Parent {
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Parent (int id0) : id(id0) { }
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int id;
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};
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struct Child : public Parent {
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Child (int id0) : Parent(id0) { }
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};
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int f1(Parent& R)
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{
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return R.id; /* Set breakpoint marker3 here. */
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}
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int f2(Child& C)
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{
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return f1(C); /* Set breakpoint marker2 here. */
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}
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int f3(const int &i)
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{
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return i;
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}
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struct OtherParent {
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OtherParent (int other_id0) : other_id(other_id0) { }
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int other_id;
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};
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struct MultiChild : public Parent, OtherParent {
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MultiChild (int id0) : Parent(id0), OtherParent(id0 * 2) { }
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};
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int mf1(OtherParent& R)
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{
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return R.other_id;
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}
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int mf2(MultiChild& C)
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{
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return mf1(C);
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}
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int main(void)
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{
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Child Q(42);
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Child& QR = Q;
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/* Set breakpoint marker1 here. */
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f2(Q);
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f2(QR);
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f3(Q.id);
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MultiChild MQ(53);
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MultiChild& MQR = MQ;
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mf2(MQ); /* Set breakpoint MQ here. */
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return 0;
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}
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