dwarfeh: version (Posix) replaced by "not Windows"

[denizzzka]

Another little thing important to support non-Windows non-Posix targets: such targets also need EH support

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[ibuclaw]

Did you not consider Cygwin?

[denizzzka]

What do you mean? Cygwin builds will be broken?

[ibuclaw]

Even Mingw is a dwarf eh platform/environment. OK, dmd has no intention of supporting either, but doesn't ldc also use this module?

[ibuclaw]

The point I'm raising is that it is not without good reason that version(!Windows) is not supported by the language. It is very bad practice to work around it by using version(Windows){} else: instead.

That said, this module isn't used by gdc, so I'll defer it to an ldc developer to check this.

[denizzzka]

The point I'm raising is that it is not without good reason that version(!Windows) is not supported by the language. It is very bad practice to work around it by using version(Windows){} else: instead.

Can we define enum/version like enableDwarfEH and then set if for needed targets?

[denizzzka]

The point I'm raising is that it is not without good reason that version(!Windows) is not supported by the language. It is very bad practice to work around it by using version(Windows){} else: instead.

What do you think about ~same #16141 ?

[kinke]

I'm kind-of sympathetic to being more bold wrt. making some existing version (Posix) the default branch for unknown targets, based on my own experience wrt. trying to get even betterC code to cross-compile for exotic platforms (still importing druntime and then e.g. complaining about undefined wchar_t). [It doesn't really help that the compiler disallows setting predefined D versions explicitly in the cmdline, just to try to compile with -version=Posix and see how far one would get.]

Even Mingw is a dwarf eh platform/environment.

Good point; so here we could disable the module for CRuntime_{Microsoft,Mars}. Edit: Or do we? I'm not sure whether CRuntime_MinGW and CRuntime_Microsoft are mutually exclusive (as the MinGW one is based on the Microsoft one...).

Can we define enum/version like enableDwarfEH and then set if for needed targets?

Yep, that's what I think would make the most sense wrt. making druntime more modularized/strippable - defining a rather coarse feature set via enums exported from some druntime config module (we cannot export versions); EH support being such a feature.

[ibuclaw]

Edit: Or do we? I'm not sure whether CRuntime_MinGW and CRuntime_Microsoft are mutually exclusive (as the MinGW one is based on the Microsoft one...).

The way gdc supports mingw is CRuntime_Microsoft that is extended with MinGW functions and features.

Debug symbols and EH table format is not wedded to any specific platform. It's an implementation detail of the compiler runtime support - a separate core to the language runtime support.

[WalterBright]

The proper way to do this is:

version (Posix) { version = DWARFEH; }
else version (AnotherOS) { version = DWARFEH; }
else version (YetAnotherOS) { version = DWARFEH; }
else static assert(0);
version (DWARFEH):

This way, there is no default OS. One still has to proactively decide what code goes with what operating system, but the above makes it reasonable.