The "buffer ID" in a SourceFile, which is used to find the source file's
contents in the SourceManager, has always been optional. However, the
effectively every SourceFile actually does have a buffer ID, and the
vast majority of accesses to this information dereference the optional
without checking.
Update the handful of call sites that provided `nullopt` as the buffer
ID to provide a proper buffer instead. These were mostly unit tests
and testing programs, with a few places that passed a never-empty
optional through to the SourceFile constructor.
Then, remove optionality from the representation and accessors. It is
now the case that every SourceFile has a buffer ID, simplying a bunch
of code.
Although I don't plan to bring over new assertions wholesale
into the current qualification branch, it's entirely possible
that various minor changes in main will use the new assertions;
having this basic support in the release branch will simplify that.
(This is why I'm adding the includes as a separate pass from
rewriting the individual assertions)
The reason why I am doing this is that I am going to be adding support for
preconcurrency imports to TransferNonSendable. That implies that we can have
preconcurrency import suppression in the SIL pipeline and thus that emitting the
diagnostic in Sema is too early.
To do this, I introduced a new module pass called
DiagnoseUnnecessaryPreconcurrencyImports that runs after the SILFunction pass
TransferNonSendable. The reason why I use a module pass is to ensure that
TransferNonSendable has run on all functions before we attempt to emit these
diagnostics. Then in that pass, we iterate over all of the modules functions and
construct a uniqued array of SourceFiles for these functions. Then we iterate
over the uniqued SourceFiles and use the already constructed Sema machinery to
emit the diagnostic using the source files.
rdar://126928265
