This flag will feature-gate work on producing more descriptive diagnostic messages.
It will remain a hidden frontend option until these improvements are ready to ship.
Use the request evaluator to get the easier in-module precedence group cycles. Unfortunately, cross-module precedence group cycles are still a possibility, and do not actually cause cyclic request evaluation, so we cannot completely erase the old diagnostics machinery.
Move the machinery itself into the type checker and shift the request into that zone as well to appease the linker.
This will make it easier to prototype diagnostics on specifically marked nominal
types. My intended usage would be to have a way to emit diagnostics if specific
instances of the nominal type are ever not on the stack.
The moment you've all been waiting for...
Define InterfaceTypeRequest and use it to, well, compute the interface
type. This naturally widens the few cycles that we pick up with the
request evaluator.
There is still a lot of work to get done here, mostly around scaling
back all of the ad-hoc circularity checks around the interface type
computation. It would also be great to improve the circularity
diagnostics.
Switch most callers to explicit indices. The exceptions lie in things that needs to manipulate the parsed output directly including the Parser and components of the ASTScope. These are included as friend class exceptions.
ReplaceOpaqueTypesWithUnderlyingTypes: We can't look through opaque archetypes if the underlying type contains a type not accessible from the current context
Use it to provide an idealized API for the VarDecl case in validateDecl.
In reality, a lot of work is needed to rationalize the dependency
structure of this request. To start, the callers of
typeCheckPatternBinding must be eliminated piecemeal. Once that is
done, the AST should introduce pattern binding decls along all the
places where getParentStmt() used to apply.
Define a request that can be used to grab the fully validated and
type-checked form of a given pattern binding entry. Using this,
validation of pattern bindings is fully disconnected from validation of
bound variables, and cycles are now picked up by the request evaluator.
Using this, we can go clean up all the callers that are checking a bit
and calling back into typeCheckPatternBinding. It will also serve as
the basis for a request for the naming pattern for a VarDecl which will
clean that part of validateDecl.
If a function builder type has a static method buildExpression(), use
it to pass through each expression whose value will become part of the
final result. This is part of the function builders pitch that had not
yet been implemented.
When Decl::getLoc() is called upon a serialized AST and the
serialized source location is available, we lazily open the
external buffer and return a valid SourceLoc instance pointing
into the buffer.
Inline the interface type reset into its callers and make sure they're
also setting the invalid bit - which this was not doing before.
Unfortunately, this is not enough to be able to simplify any part of var
decl validation.
This is an amalgam of simplifications to the way VarDecls are checked
and assigned interface types.
First, remove TypeCheckPattern's ability to assign the interface and
contextual types for a given var decl. Instead, replace it with the
notion of a "naming pattern". This is the pattern that semantically
binds a given VarDecl into scope, and whose type will be used to compute
the interface type. Note that not all VarDecls have a naming pattern
because they may not be canonical.
Second, remove VarDecl's separate contextual type member, and force the
contextual type to be computed the way it always was: by mapping the
interface type into the parent decl context.
Third, introduce a catch-all diagnostic to properly handle the change in
the way that circularity checking occurs. This is also motivated by
TypeCheckPattern not being principled about which parts of the AST it
chooses to invalidate, especially the parent pattern and naming patterns
for a given VarDecl. Once VarDecls are invalidated along with their
parent patterns, a large amount of this diagnostic churn can disappear.
Unfortunately, if this isn't here, we will fail to catch a number of
obviously circular cases and fail to emit a diagnostic.
VarDecls inherit their TypeRepr from their enclosing pattern, if any.
To retrieve the TypeRepr attached to a VarDecl or a ParamDecl in
a uniform way, the getTypeReprOrParentPatternTypeRepr API has been
provided.
We can't access types in the same module if they are private: they could
be in a different TU.
We can't access types from different modules if they are private or
internal.
Some more information can be gleaned from the resilience expansion: A
minimally resilient function can't reference private or internal types.
rdar://56093964
