I think that preferring identical over convertible makes sense in e.g. C++ where we have implicit user-defined type conversions but since we don’t have them in Swift, I think the distinction doesn’t make too much sense, because if we have a `func foo(x: Int?)`, want don’t really want to prioritize variables of type `Int?` over `Int` Similarly if we have `func foo(x: View)`, we don’t want to prioritize a variable of type `View` over e.g. `Text`.
rdar://91349364
At least for now, ide::typeCheckContextAt() doesn't call
'typeCheckASTNodeAtLoc()' with function decl signature position.
Also, 'getIntefaceType()' on function reference doesn't call decl
checker. So we don't need to propagate it.
Introduce 'TypeCheckSingleASTNode' mode that only type checks single body
element and dependent necessities (i.e. referencing ValueDecls and their
dependencies).
Renamed swift::typeCheckAbstractFunctionBodyAtLoc() to
swift::typeCheckASTNodeAtLoc(DeclContext *, SourceLoc). That type checks
innermost 'ASTNode' at the location. Also, 'TypeCheckSingleASTNode' mode
skips type checking any "body" of the node (i.e. BraceStmt elements for
function body, if statement body, closure body, etc.)
Added on-demand type checking using it:
- VarDecl in TapExpr
- ParamDecl in ClosureExpr
- Return type of ClosureExpr
- Binding value in control statements
(e.g. ForEachStmt, SwitchStmt, DoCatchStmt, etc.)
rdar://problem/63932852
For example for:
funcName(base.<HERE>)
Wrap 'base' with 'CodeCompletionExpr' so that type checker can check
'base' independently without preventing the overload choice of 'funcName'.
This increases the chance of successful type checking.
rdar://problem/63965160
