Can't build on Fedora 30

[Mathok]

error.cc:35:54: error: non-local lambda expression cannot have a capture-default
35 | function<void(string s)> current_catch_explainer = [&](string s) {
| ^
make[1]: *** [Makefile:47: error.o] Error 1

the bug happens with 0.6.1 and git master and there is also a gentoo bugtracker entry for this https://bugs.gentoo.org/685714

[automorphism88]

Does Fedora include GCC 9? Because on Gentoo, that error occurs with GCC 9.1, but it builds fine with GCC 8.3. I haven't tried clang or any other GCC versions.

[kakra]

This affects both the 0.6 branch and the master branch.

@Zygo Should we fix and backport to 0.6, or move forward to an 0.7 version?

[Zygo]

That lambda doesn't need a capture, because there's nothing in scope that it could capture that the function body doesn't already have access to. Apparently that's an error in C++11, but no version of GCC before 9 notices this.

@kakra We should probably go forward to 0.7 because it's long overdue.

I had wanted to do a bunch of stuff in 0.7, but then other plans took priority, and I also wandered away from bees for a bit to fight kernel bugs for a while. So I think I'm just going to push out a few small fixes for 0.7 soon, and try to get the bigger stuff done in 0.8.