[llvm-dev] clang-cl and exceptions

[Reid Kleckner via llvm-dev]

This was intentional, since the old implementation was broken. VS projects
set /EHsc by default, so users who weren't actively using EH were
automatically getting EH anyway, which would crash the compiler. I can't
reasonably ask everyone who wants to try clang to manually change their VS
project settings, so I made clang-cl temporarily ignore /EHs.

We've started over with new LLVM IR constructs for representing Windows EH,
and when that's done, we can make /EHs enable it. For now you have to pass
all of the following to clang-cl to try the new implementation:
-Xclang -fexceptions -Xclang -fcxx-exceptions -Xclang -fnew-ms-eh

The current status is that we can catch some 32-bit exceptions, but will
usually crash at runtime. The compiler will reject destructor cleanups very
late during codegen.

Hope that helps.

For future reference, this is more of a cfe-dev kind of topic.

On Wed, Sep 2, 2015 at 3:25 AM, Russell Wallace via llvm-dev <
llvm-dev at lists.llvm.org> wrote:

> Tried a small test just now to see how exception handling on Windows is
> getting on, and it seems to work except for one thing.
>
> clang-cl /EHsc (the Microsoft compiler option to enable exceptions)
> doesn't do anything; they remain disabled. However, -Xclang
> -fcxx-exceptions succeeds. Is this a bug in the handling of compatibility
> options or am I missing something?
>
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