This is the mail archive of the
gdb@sourceware.org
mailing list for the GDB project.
GDB syntax error when casting to base class
- From: Marc Khouzam <marc dot khouzam at ericsson dot com>
- To: "'gdb at sourceware dot org'" <gdb at sourceware dot org>
- Date: Thu, 9 Sep 2010 08:50:07 -0400
- Subject: GDB syntax error when casting to base class
Hi,
I got an eclipse bug report that led me to a bizarre behavior from GDB.
In the very short session below, I'm getting a syntax error when casting
a variable to its base class.
If I remove the constructor (see comment in the code below)
the problem goes away. Or if I add the word 'struct', it also goes away.
This is causing problems in Eclipse because -var-info-path-expression
returns the expression that causes a syntax error.
I tried to debug it but I ended up in c-exp.y and had to give up.
I was going to propose a patch that adds 'struct' to the
-var-info-path-expression output, but I didn't think that was the
greatest of solutions. Currently, this is what we are planning to
do in Eclipse to work around this problem.
I can open a PR if it makes sense?
Thanks
Marc
> gdb.7.2 a.out
GNU gdb (GDB) 7.2
(gdb) l 1
1 class bar{};
2
3 class foo : public bar {
4 public:
5 foo() {} // Comment this line to make things work
6 void test() { return; }
7 };
8
9 int main(void)
10 {
11 foo f;
12 f.test();
13 return 0;
14 }
(gdb) b 6
Breakpoint 1 at 0x8048457: file base.cc, line 6.
(gdb) r
Starting program: /local/lmckhou/testing/a.out
Breakpoint 1, foo::test (this=0xbfffbfa3) at base.cc:6
6 void test() { return; }
(gdb) p (*(bar*) this)
A syntax error in expression, near `) this)'.
(gdb) p (*(struct bar*) this)
$1 = {<No data fields>}