DAWN-486 ⁃ WASM doesn't call constructor for globally initialized objects

[brianjohnson5972]

If the following code is included in wasm and run, it passes, since it appears that objects allocated in global space are just initialized to 0 and doesn't run the ctor.

Found emscripten-core/emscripten#5391, so we may need to get a more recent emscripten.

class test_init
{
public:
   test_init()
   : _0(0)
   , _1(1)
   {
      _2 = 2;
   }

   bool operator==(const test_init& rhs)
   {
      return _0 == rhs._0 && _1 == rhs._1 && _2 == rhs._2;
   }

   int _0;
   int _1;
   int _2;
} init0;

void test_init()
{
   test_init init1;
   test_init init2;
   assert ( init1 == init2, "init1 should equal init2");
   assert ( init1._0 == 0, "expected _0 to be 0");
   assert ( init1._1 == 1, "expected _1 to be 1");
   assert ( init1._2 == 2, "expected _2 to be 2");
   assert ( init0._0 == 0, "expected _0 to be 0");
   assert ( init0._1 == 0, "expected _1 to be 1, but it is 0");
   assert ( init0._2 == 0, "expected _2 to be 2, but it is 0");
   assert ( !(init1 == init0), "init1 should equal init0, but it doesn't");
}

[blockone-syncclient]

➤ Corey Lederer commented:

From Bart's comment on old ticket:

FWIW, this is not the job of the Virtual Machine in the c++ spec. It is the job of the compiler tool-chain/runtime library. In compilers compatible with the GNU libc(++) runtimes the linker will produce __CTOR_LIST__ and __DTOR_LIST__ symbols and the runtime entry point (which isn't actually "main") will call those and then call "main".

The runtime dependency in implementing this that way is a working "atexit" function to call the __DTOR_LIST__

We don't actually use EMSCRIPTEN to compile our wasm. That is the glue between WASM and a browser, that provides all of these runtime features. We would need to emulate what they did to support some of these things.

[andriantolie]

@brianjohnson5972 is this issue still relevant?

[brianjohnson5972]

@spoonincode What is the state of this issue with our current supported libraries?

[spoonincode]

This should be working with eosio.cdt afaik

@larryk85

[larryk85]

eosio.cdt fixes these issues.