What does -vtls compiler flag does and ...

[Stanislav Blinov]

On Wednesday, 3 October 2018 at 20:41:15 UTC, welkam wrote:
> I was playing around with dmd`s make file trying to see if I 
> can compile dmd with different compilers and different 
> compilation flags. By playing around I found that some dmd 
> files are compiled with -vtls flag unconditionally and that ldc 
> do not support this flag. First I dont know what -vtls flag 
> does so I looked at documentation...

> Aren't all variables thread local unless explicitly specified?

No, all *static non-immutable* variables are thread-local by 
default, not just "all variables".

> What this flag does? Why some files compiled with it and other 
> dont? Why it is added to all compilation targets 
> unconditionally?

It does what it says, just prints some diagnostic info. You can 
just ignore it, i.e. not use it. As for why it's in the makefile, 
I can only guess that someone keeps it there for diagnostic 
purposes :)