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* [Bug c++/18888] New: unable to evaluate NULL
@ 2015-08-28 21:49 msebor at redhat dot com
2022-04-02 16:48 ` [Bug c++/18888] " tromey at sourceware dot org
0 siblings, 1 reply; 2+ messages in thread
From: msebor at redhat dot com @ 2015-08-28 21:49 UTC (permalink / raw)
To: gdb-prs
https://sourceware.org/bugzilla/show_bug.cgi?id=18888
Bug ID: 18888
Summary: unable to evaluate NULL
Product: gdb
Version: 7.8
Status: NEW
Severity: normal
Priority: P2
Component: c++
Assignee: unassigned at sourceware dot org
Reporter: msebor at redhat dot com
Target Milestone: ---
GNU gdb (GDB) Fedora 7.8.2-38.fc21 doesn't seem to know about GCC's __null
extension used to implement the NULL macro. When the NULL macro is used in the
definition of a function like macro as happens to be the case with some of the
GCC tree checking macros such as DECL_ASSEMBLER_NAME_SET_P, GDB issues the
cryptic error 'No symbol "__null" in current context.' when an attempt is to
evaluate an invocation of the macro. This makes GCC debugging harder than it
would be otherwise.
(gdb) p DECL_ASSEMBLER_NAME_SET_P(expr)
No symbol "__null" in current context.
Test case:
$ cat t.c && g++ -g3 t.c && gdb -batch -ex 'b main' -ex 'r' -ex 'macro expand
FOO(p, 1, 2)' -ex 'p FOO(p, 1, 2)' a.out
#include <stdlib.h>
#define FOO(a, b, c) a == NULL ? b : c
int main ()
{
void *p = NULL;
int n;
n = FOO (p, 1, 2);
return n;
}
Breakpoint 1 at 0x4005ba: file t.c, line 7.
Breakpoint 1, main () at t.c:7
7 void *p = NULL;
expands to: p == __null ? 1 : 2
No symbol "__null" in current context.
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* [Bug c++/18888] unable to evaluate NULL
2015-08-28 21:49 [Bug c++/18888] New: unable to evaluate NULL msebor at redhat dot com
@ 2022-04-02 16:48 ` tromey at sourceware dot org
0 siblings, 0 replies; 2+ messages in thread
From: tromey at sourceware dot org @ 2022-04-02 16:48 UTC (permalink / raw)
To: gdb-prs
https://sourceware.org/bugzilla/show_bug.cgi?id=18888
Tom Tromey <tromey at sourceware dot org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |tromey at sourceware dot org
--- Comment #1 from Tom Tromey <tromey at sourceware dot org> ---
See also bug #15243, about nullptr.
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2015-08-28 21:49 [Bug c++/18888] New: unable to evaluate NULL msebor at redhat dot com
2022-04-02 16:48 ` [Bug c++/18888] " tromey at sourceware dot org
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