Mike Hommey

FWIW, there is something similar happening when setting head_space and foot_space, but not line_length: the last line in a paragraph doesn't use the same character spacing as the other lines.

There are other considerations than straight license compatibility. For an example I have been directly involved with, the LGPL was designed against closed-source software, at the expense of copyleft free...

Here is a reduced testcase (not minimal) from real (yes, broken, invoking UB) code, that, because the mentioned debug_assert is not hit, leads to a completely unrelated panic that "can't...

> Isn't it caused by `-O`? `RUSTFLAGS=-O` is synonym for `-C opt-level=2`, which [_does not_ implies `cfg(debug_assertions)`](https://doc.rust-lang.org/rustc/codegen-options/index.html#opt-level) (`debug_assert!` is compiled into no-op if `debug_assertions` is turned off). You should experiment...

The problem is that those debug_assert are followed with hints to the compiler that what's being asserted doesn't happen. So we're in a situation where UB will lead to (rightful)...

> > I don't see build-std becoming usable with cargo vendor any time soon. > > Can you elaborate on that? I don't know how vendoring interacts with build-std. rust-src...

> Shameless plug, [cargo-careful](https://github.com/RalfJung/cargo-careful/) also enables these checks. No idea if that works with cargo-vendor though. It sounds like it only works on `bin` crates.

Stupid example: Run `cargo build --timings` and `cargo build --timings --release` at the same time in two terminals. Without looking at the output in each terminal, how do you tell...

How is this related to #5806?

So, if I understand correctly, this only "fixes" #5806 for crates published to crates.io, but e.g. crates vendored from a git repo, will still have the problem.