> What's not possible is to get code compiled by a specific compiler to call modules built by another compiler provided by another vendor. That's the only problem that is addressed by a common ABI.

Yes, compilers need to agree on the ABI, the platform ABI, that is. Today most platforms already have a de-facto or de-jure standard ABI and compilers have the option to implement it.

Even if such a thing was possible, there is no value in the standard committee standardizing an single ABI as most platforms would never break backward compatibility to switch to it.