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 :)
Added impl of `fmt::Display` for `Cfg`
Added `fn matched_defines(…)` for filtering for matches in `[defines]`
Changes semantic of `has_defines` from `∀` to `∃` (i.e. all -> one or more)
Changed `write_before` to use `matched_defines`
Added logging of warning for omitted `#[cfg(…)]`s
Added expectations for `mod_attr` test project
Renamed function arguments in `mod_attr` test project
Rustfmt
Introduced `Condition` type to ensure correct API usage of `Cfg`
Merged `Condition::Boolean` and `Condition::Named` into `Condition::Define`
Removed `DefineConfig` and `MissingDefineBehavior`.
(Was getting a bit ahead of myself with these.)
Rustfmt
Vadim Petrochenkov
Kartikaya Gupta
Emilio Cobos Álvarez
Dan Robertson
Vincent Esche