Previously we used the default inst block formatting, which writes out a
parenthesized list of references, which would always be 'unexpected
instref's because nothing else prints the instructions in the decl
block.
In addition, track the decl block for function declarations like we do
for other kinds of declaration. This means that the parameter
declarations for a function are now properly rendered into the formatted
IR. Note that this adds a lot of verbosity to `function_decl`, but it
does accurately reflect the IR, and we'll probably want this information
to be printed once we start supporting more complex generic function
declarations.
This removes almost all the 'unexpected instref's in our formatted
output. There are remaining cases when a declarative scope contains
multiple blocks, where we only track one of those blocks. That happens
when there is control flow within declarative scopes, and for error
recovery when a class or interface or similar is defined more than once.
As requested in #3730.
This works by creating a faux FunctionDecl in the context of the current
IR, which seems to be working for function calls. Deduced params are
there, but won't really be tested until classes are up and running. Also
I may need to look further at return_slot_id to ensure it's working. But
the basics, I think, are here.
Reorganizes some other ImportRef work from `has_unresolved` that'd
relied on manual calls to a more detection-based `HasUnresolved`
approach that doesn't require as much checking.
Richard Smith
Jon Ross-Perkins