Now that we're checking DiscardAssignmentExprs in PreCheckExpr, we have to be careful to make sure we don't diagnose anything until after SequenceExprs have been folded, since the relevant AssignExprs won't even have a "right hand side" and "left hand side" until after folding.
Move markAcceptableDiscardExprs into PreCheckExpr so that we can perform this analysis before we convert expressions like `_? = <value>` into `_ = <value>` since `_?` is now an expression with meaning, and we only want to perform this transformation when `_?` is on the LHS of an assignment
Unwrap `InOutExpr` from all parens until the outermost paren or a tuple
to correctly diagnose calls like `foo(((&bar)))` or `foo(x: (&bar))`,
and suggest a fix-it with moves `&` outside parens.
Resolves: rdar://problem/71356981
Two fixes here:
- The ASTScopeDeclConsumerForLocalLookup needs to visit auxiliary variables
- preCheckExpression() should call ASTScope::lookupLocalDecls() even when
parser lookup is enabled, since otherwise we won't be able to find
auxiliary decls in the current DeclContext.
Before performing an UnqualifiedLookup with Flags::IncludeOuterResults
turned on, call ASTScope::lookupSingleLocalDecl() to find local
bindings that precede the current source location.
If this fails, we perform an unqualified lookup to try to find
forward references to captures, type members, and top-level
declarations.
