[Bug analyzer/100705] New: warn about dead store

[Bug analyzer/100705] New: warn about dead store

[mail at milianw dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100705

            Bug ID: 100705
           Summary: warn about dead store
           Product: gcc
           Version: 11.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: analyzer
          Assignee: dmalcolm at gcc dot gnu.org
          Reporter: mail at milianw dot de
  Target Milestone: ---

Hey there,

in a large code base I'm working on I stumbled over code in one area that
basically did the below, but in a more elaborate manner. It would have been
quite helpful to get a warning when `-fanalyzer` is passed, because in my
opinion, this code is bogus:

```
struct Properties
{
    int foo = 0;
    int bar = 0;
};

Properties asdf()
{
    Properties ret;
    ret.foo = 42; // warning: this has no effect
    ret.bar = 1;
    ret.foo = 12; // b/c it's unconditionally overwritten here
    return ret;
}
```

Thanks

[Bug analyzer/100705] RFE: warn about dead store

[dmalcolm at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100705

David Malcolm <dmalcolm at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|warn about dead store       |RFE: warn about dead store

--- Comment #1 from David Malcolm <dmalcolm at gcc dot gnu.org> ---
Thanks for filing this RFE.

Some notes:

"CWE-563: Assignment to Variable without Use":
  https://cwe.mitre.org/data/definitions/563.html

PVS-Studio implements this as V-519:
  https://pvs-studio.com/en/docs/warnings/v519/
  https://pvs-studio.com/en/blog/examples/v519/
    (lots of examples at that link)

I'm not sure how well this ties into what the analyzer is already doing,
though.

[Bug analyzer/100705] RFE: warn about dead store

[egallager at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100705

Eric Gallager <egallager at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |egallager at gcc dot gnu.org
           Keywords|                            |diagnostic

--- Comment #2 from Eric Gallager <egallager at gcc dot gnu.org> ---
I think there's another bug open for this, but I can't find it at the moment...

[Bug analyzer/100705] RFE: warn about dead store

[dmalcolm at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100705

--- Comment #3 from David Malcolm <dmalcolm at gcc dot gnu.org> ---
See also: PR 80066