Ideally we'd just do this when we need it, but the ostream derivation
will be controlled by both global config and per-structure config, so
it's hard to know exactly when we need it and when we don't.
Using operator= is not quite sound in presence of destructors and operator
overloading.
It's perfectly fine to assume that the left-hand-side of an operator= expression
is valid memory, however we're using uninitialized memory here, that may not be
the case.
Use placement new to properly construct tagged unions. I don't need this with
any urgency, but it's the right thing to do in presence of complex types, and
the current code seems a bomb waiting to explode :)
cbindgen currently assumes that the `Cargo.lock` is in directly in the
crate directory as a sibling to `Cargo.toml`; however that is usually
not the case inside a workspace.
Instead, this PR extracts the workspace root from the output of `cargo
metadata` [1] (already used to get a list of packages) and uses the
`Cargo.lock` from there.
1. This is available since Rust 1.24; see rust-lang/cargo#4940
Emilio Cobos Álvarez
Kartikaya Gupta
Dan Robertson
Basile Clement