GCC analyzer false positive

[Iain Buclaw]

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.