D.gnu - GCC analyzer false positive
- Zachary Yedidia (33/33) Aug 31 2023 The following code generates a warning when using GCC analyzer,
- Iain Buclaw (9/42) Sep 01 2023 Hi,
- Iain Buclaw (6/20) Sep 22 2023 I'm at the GNU Cauldron, and David has just said "don't use
The following code generates a warning when using GCC analyzer,
but I don't think the warning is valid.
```
struct Guard {
~this() {}
}
Guard lock() {
return Guard();
}
void bar() {
auto foo = lock();
}
```
Compiled with GCC version 13.1:
```
$ gdc -fanalyzer test.d -O2 -c
test.d: In function 'lock':
test.d:5:5: warning: use of uninitialized value 'MEM[(unsigned
char * {ref-all})&D.3438]' [CWE-457]
[-Wanalyzer-use-of-uninitialized-value]
5 | return Guard();
| ^
'lock': events 1-2
|
| 5 | return Guard();
| | ^
| | |
| | (1) region created on stack here
| | (2) use of uninitialized value 'MEM[(unsigned
char * {ref-all})&D.3438]' here
|
```
Any ideas? Thanks!
Aug 31 2023
Iain Buclaw <ibuclaw gdcproject.org>
On Thursday, 31 August 2023 at 13:53:55 UTC, Zachary Yedidia
wrote:
The following code generates a warning when using GCC analyzer,
but I don't think the warning is valid.
```
struct Guard {
~this() {}
}
Guard lock() {
return Guard();
}
void bar() {
auto foo = lock();
}
```
Compiled with GCC version 13.1:
```
$ gdc -fanalyzer test.d -O2 -c
test.d: In function 'lock':
test.d:5:5: warning: use of uninitialized value 'MEM[(unsigned
char * {ref-all})&D.3438]' [CWE-457]
[-Wanalyzer-use-of-uninitialized-value]
5 | return Guard();
| ^
'lock': events 1-2
|
| 5 | return Guard();
| | ^
| | |
| | (1) region created on stack here
| | (2) use of uninitialized value 'MEM[(unsigned
char * {ref-all})&D.3438]' here
|
```
Any ideas? Thanks!
Hi,
Thanks for posting this!
Had a quick poke around - also with a C++ equivalent test - and
it looks like GCC's static analyzer is not good at dealing with
returning non-trivially copyable struct via NRVO.
I'll have a prod a bit more later, but my first instinct would be
to raise a bug report with GCC.
Sep 01 2023
On Thursday, 31 August 2023 at 13:53:55 UTC, Zachary Yedidia
wrote:
The following code generates a warning when using GCC analyzer,
but I don't think the warning is valid.
```
struct Guard {
~this() {}
}
Guard lock() {
return Guard();
}
void bar() {
auto foo = lock();
}
```
Compiled with GCC version 13.1:
I'm at the GNU Cauldron, and David has just said "don't use
-fanalyzer on C++ in GCC 13, you will get rubbish out of it".
This would also extend to all other languages that aren't C too.
The good news is that things are going to be improved in GCC 14.
Sep 22 2023