On Wed, 2023-08-30 at 14:25 +0200, Mathieu Malaterre via Gcc-help wrote:
> Hi all,
>
> Consider the following silly c++ code (*), it compiles nicely using
> g++ 13.2 no warnings using either:
>
> % g++ -c -O2 -Wall -Wextra alt.cxx
>
> or
>
> % g++ -c -O0 -Wall -Wextra alt.cxx
>
> Is it possible to trigger a warning for this code (maybe I missed some
> gcc options) ?
Analyzer does a better job for such a "complex" pattern:
$ gcc -Wall -Wextra t.cc -fanalyzer -S
t.cc: In function 'void k()':
t.cc:8:21: warning: use of uninitialized value 'di' [CWE-457] [-Wanalyzer-use-of-uninitialized-value]
8 | long actual = cl(di);
| ~~^~~~
'void k()': events 1-3
|
| 7 | d di;
| | ^~
| | |
| | (1) region created on stack here
| | (2) capacity: 64 bytes
| 8 | long actual = cl(di);
| | ~~~~~~
| | |
| | (3) use of uninitialized value 'di' here
|
Unfortunately analyzer is still C-only (it may work for simple C++ test
cases but it's still not suitable for real C++ programs) as at now.
> Thanks !
>
>
> (*)
> % cat alt.cxx
> #include <cstdlib>
> struct d {
> long cj[sizeof(long)];
> };
> long cl(d b) { return b.cj[0]; }
> void k() {
> d di;
> long actual = cl(di);
> if (actual == 0)
> std::exit(42);
> }
>
--
Xi Ruoyao <xry111@xxxxxxxxxxx>
School of Aerospace Science and Technology, Xidian University
