[webkit.UncountedLambdaCapturesChecker] Recognize nested protectedThis pattern (#126443)

In WebKit, it's pretty common to capture "this" and "protectedThis"
where "protectedThis" is a guardian variable of type Ref or RefPtr for
"this". Furthermore, it's common for this "protectedThis" variable from
being passed to an inner lambda by std::move. Recognize this pattern so
that we don't emit warnings for nested inner lambdas.

To recognize this pattern, we introduce a new DenseSet,
ProtectedThisDecls, which contains every "protectedThis" we've
recognized to our subclass of DynamicRecursiveASTVisitor. This set is
now populated in "hasProtectedThis" and "declProtectsThis" uses this
DenseSet to determine a given value declaration constitutes a
"protectedThis" pattern or not.

Because hasProtectedThis and declProtectsThis had to be moved from the
checker class to the visitor class, it's now a responsibility of each
caller of visitLambdaExpr to check whether a given lambda captures
"this" without a "protectedThis" or not.

Finally, this PR improves the code to recognize "protectedThis" pattern
by allowing more nested CXXBindTemporaryExpr, CXXOperatorCallExpr, and
UnaryOperator expressions.

0 files changed, 0 insertions, 0 deletions