[scatters]

At -O2 or above, gcc emits Wreturn-local-addr.

[renox]

Yep, ‘-O2 or above’ we used to compile our UTs without optimizations because otherwise it takes too long, but now we have an additional(less frequent) CI job for UT with optimizations to benefit from these improved error detection.

[mlyle]

Within a single compilation unit, and only in this most trivial case.

[WalterBright]

Here's an example of a much more complex case that is detected:

https://issues.dlang.org/show_bug.cgi?id=21745

[mlyle]

Yes, sorry if my comment isn't clear. D is very capable in this regard. While gcc with C/C++ code will spot a few trivial cases... including the one in the example above.