error: cannot compile this aggregate va_arg expression yet

[nick7ikin]

Hi,

I'm not C-guru, so maybe I'm doing something wrong...

So I'm trying to compile pthread library using emscripten. I know that javascript and emscripten have a threading model quite different from native one, but here is another issue. I run the following commands

emconfigure ./configure --disable-shared --enable-static
emmake make

and got compiler error:

/home/user/emscripten/system/include/libc/sys/signal.h:1:2: warning: redirecting incorrect #include <sys/signal.h> to <signal.h> [-W#warnings]
#warning redirecting incorrect #include <sys/signal.h> to <signal.h>
 ^
pth_event.c:155:25: error: cannot compile this aggregate va_arg expression yet
        pth_time_t tv = va_arg(ap, pth_time_t);
                        ^~~~~~~~~~~~~~~~~~~~~~

This is strange cause I installed emscripten a week ago, so it is quite fresh. Could you please give any suggestion how to handle it?

[kripken]

This is a limitation of the current llvm target that we use. Not sure how easy it is to fix, hoping @sunfishcode does. Also you can look in the mailing list for this, I think it came up there too.

[aknuds1]

I'm hitting this limitation as well, in trying to build ChucK :/

[ericrannaud]

With a couple of small patches pulled from PNaCl, it seems support can be easily added:
emscripten-core/emscripten-fastcomp#53
emscripten-core/emscripten-fastcomp-clang#4

I tested the changes on existing code that uses va_arg(..., struct) and it now compiles and runs OK. However, I am not familiar with the code and I can't evaluate how safe this change is. I haven't run the full emscripten test suite yet.

Let me know if this needs more work. Thanks.

[ericrannaud]

This change does not support nested structs. I have added a couple of tests for this feature in emscripten (see pull request #2923). One for flat structs (enabled), one for nested structs (disabled for now).

See also https://code.google.com/p/nativeclient/issues/detail?id=3815

[stale]

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