Run the tests in C++ mode

[Araq]

Since the new runtime will depend on implicit try finally constructs quite a bit more than it used to, it's important we ensure the C++ target is alive and kicking. For this Nim's tester testament and the CIs need a mode that run every non-JS-test with nim cpp so that we can see where we used importc constructs etc that bite with the C++ target (this will be mostly const issues).

[arnetheduck]

well, with the targets list, it's possible to run each test with both c and c++ targets.. gonna take a while but might be worth it - else the C target will become what C++ is today - unhappy.

speaking of targets, which C and C++ version specifically? perhaps this should be specified and tested for?

[Araq]

well, with the targets list, it's possible to run each test with both c and c++ targets.. gonna take a while but might be worth it - else the C target will become what C++ is today - unhappy.

Yeah, well, I agree. Both should be tested constantly.

speaking of targets, which C and C++ version specifically? perhaps this should be specified and tested for?

Roughly C89 (oldest C version that makes sense) and the most recent C++ version (assuming C++ is getting more strict / more clearly specified all the time). Alternatively the C++ that Visual Studio actually supports...

[andreaferretti]

I think that C++ is more of a moving target than C is, and relying on a moving target is much more work - see what happened to JVM languages and scala in particular since java started moving again.

In my opinion it is nice that Nim can compile to C++, keeping C as the reference target is a safer bet

[zah]

The point is that C++ implements our run-time better (through its better support for exceptions handling). It's high time that we fix the various small issues that make using C++ less practical. The modern C++ standards make only relatively small changes to the small subset of C++ that we use, so it will be much less of a problem to switch between them.

[andreaferretti]

Granted, but the C compiler has advantages as well:

• faster compilation times
• C is a simpler and much more known language, should one inspect nimcache
• it is easier to generate libraries that can be used from other languages

In general, when language A compiles down to language B, you sort have to know B even if you only work with A - be it for debugging, FFI, understanding performance and so on. C is a relatively simple language, and the burden of understanding basic C concepts is not high. Nim is powerful but complex because of the interaction of many features. C++ also is powerful and complex.

If C++ becomes the de facto target, users will have more difficulties learning Nim - I, for one, have a very basic understanding of the subtleties of C++

[Araq]

If C++ becomes the de facto target, users will have more difficulties learning Nim - I, for one, have a very basic understanding of the subtleties of C++

The code generator treats C++ as a C with try statements, there is nothing to worry about.

faster compilation times

Since sighashes arrived in Nim, for me most time is spent in the Nim compiler itself.

it is easier to generate libraries that can be used from other languages

You can keep using the C backend for this, it's not going away.

[andreaferretti]

Good to know, I was a little worried :-)

[data-man]

C++ backend could use std :: iterators for Nim's iterators.

Also, newest g++ and clang supports a concepts.

Just a dreams. :)

[arnetheduck]

in general, the more you rely on c++ features, the more you'll have to make nim follow c++ semantics, or live with subtle edge case bugs that will appear when you least want or need them too - far into your project when changing it is expensive..

also, would be interesting to see numbers on what the c++ backend does to binaries in terms of RTTI etc - a trivial test might be to bootstrap nim compiler with c and c++, and see which one runs the test suite better.

[arnetheduck]

Roughly C89

if that's the case / if that's advertised / if that's a feature, perhaps at least the linux tests should run with that gcc flag enabled (-std=c89 --pedantic)

[data-man]

Support for iterators and C++ concepts has a huge advantage: a generated code will be compatible with tons of modern C++ libraries, including std :: *