[PATCH] D47564: [Parse] Use CapturedStmt for @finally on MSVC

[Shoaib Meenai via Phabricator via cfe-commits]

smeenai added a comment.

In https://reviews.llvm.org/D47564#1118381, @rjmccall wrote:

> That's an interesting idea.  I don't see any particular reason not to do it this way if you're willing to accept that it's never going to support the full control-flow possibilities of @finally.  You will need to add JumpDiagnostics logic to prevent branches out of the block, and I don't know how this will interact with attempts to throw an exception out.


There's already some logic in CapturedStmt to prevent branches out of the block:

- Attempting to return will produce "cannot return from Objective-C @finally statement"
- Attempting to goto out of the block will result in "use of undeclared label", which is a bad diagnostic (and should be improved), but it does error

Are there any other branches you had in mind? I could add tests for them, perhaps, though it's also covered by `test/Sema/captured-statements.c`.

It should be possible to add support for returns, at least; the idea we'd discussed with @rnk was setting a flag in the captured function to indicate a return having been executed, and then reading that flag outside the captured function and acting on it appropriately. gotos would be more complicated, but I think we could make them work if we really wanted to.

Throwing an exception out should just work, I think; the outlined function will just participate normally in exception handling. Did you have a specific case you were thinking of?


Repository:
  rC Clang

https://reviews.llvm.org/D47564