[Issue 20809] return statement might access memory from destructed temporary

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=20809

Dennis <dkorpel at live.nl> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |safe
                 CC|                            |dkorpel at live.nl
           Hardware|x86_64                      |All
                 OS|Linux                       |All

--- Comment #8 from Dennis <dkorpel at live.nl> ---
This is important for making Phobos's tempCString @safe:

```
    // $(RED WARNING): $(RED Incorrect usage)
    auto pInvalid1 = str.tempCString().ptr;
    const char* pInvalid2 = str.tempCString();
    // Both pointers refer to invalid memory here as
    // returned values aren't assigned to a variable and
    // both primary expressions are ended.
```

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