Doug Gregor 65a9bff5b0 Rework mangling of macro expansions in local contexts to not trigger type checking. ...

The mangling of macro expansions relies on having a type-checked AST
for its enclosing context. When that enclosing context is within a
local context (say, a local type), mangling would trigger type
checking of that local type, which could then involve assigning local
discriminators. However, if this happens before type checking of the
enclosing function body, we would end up failing to assign closure
discriminators to (e.g.) autoclosures within the body.

The fundamental problem here is the interaction between discriminator
assignment (which can only happen after type checking) and mangling of
macro expansion buffers (which can happen during that type checking).
Break this cycle by providing a different approach to mangling macro
expansions within local contexts as the innermost non-local context +
a name-based discriminator within that local context. These manglings
are not ABI and are not stable, so we can adjust them later if we come
up with a scheme we like better. However, by breaking this cycle, we
eliminate assertions and miscompiles that come from missing
discriminators in this case.

Fixes rdar://139734958.

2024-12-05 16:09:02 -08:00

27 KiB

Raw Blame History

View Raw