Due to a bug in how macros on nodes imported from clang are evaluated,
their function body is not always type checked. This forces type
checking before silgen of a macro originating on a node imported from
clang, to prevent crashing in silgen.
rdar://150940383
(cherry picked from commit efd70b1f54)
The Clang importer maps arbitrary attributes spelled with `swift_attr("...")`
over to Swift attributes, using the Swift parser to process those attributes.
Extend this mechanism to allow `swift_attr` to refer to an attached macro,
expanding that macro as needed.
When a macro is applied to an imported declaration, that declaration is
pretty-printed (from the C++ AST) to provide to the macro implementation.
There are a few games we need to place to resolve the macro, and a few more
to lazily perform pretty-printing and adjust source locations to get the
right information to the macro, but this demonstrates that we could
take this path.
As an example, we use this mechanism to add an `async` version of a C
function that delivers its result via completion handler, using the
`@AddAsync` example macro implementation from the swift-syntax
repository.
Swift has some module maps it overlays on Linux and Windows that groups all of the C standard library headers into a single module. This doesn’t allow clang and C++ headers to layer properly with the OS/SDK modules. clang will set -fbuiltin-headers-in-system-modules as necessary for Apple SDKs, but Swift will need to pass that flag itself when required by its module maps.
`module.map` as a module map name has been discouraged since 2014, and
Clang will soon warn on its usage. This patch renames all instances of
`module.map` in the Swift tests to `module.modulemap` in preparation
for this change to Clang.
rdar://106123303
