[cfe-dev] Clang-tidy check for preprocessor marked functions

[Roman Lebedev via cfe-dev]

On Thu, Jun 22, 2017 at 5:40 PM, Marc-André Lureau via cfe-dev
<cfe-dev at lists.llvm.org> wrote:
> Hi,
>
> I have started to investigate using clang-tidy for some QEMU checks and
> modernization, with some success. I started sending patches to the QEMU ML
> (https://lists.nongnu.org/archive/html/qemu-devel/2017-06/msg05034.html).
> The QEMU maintainer, Peter, challenged me to see if we could write a check
> for coroutine usage: check if there are calls to a coroutine-marked function
> from a non-coroutine (which would be a bug, as coroutine may yield).
> Coroutine function are marked with a "coroutine_fn" macro, this a simple
> example:
>
> #define coroutine_fn
>
> void coroutine_fn qemu_coroutine_yield(void);
>
> int main(int argc, char *argv[])
> {
>     qemu_coroutine_yield();
>     return 0;
> }
>
>
> Here, qemu_coroutine_yield() should be an error, because main() is not a
> coroutine_fn.
>
> Is there a way to write a clang-tidy check, perhaps at PP level, that would
> mark the function declaration with coroutine type?
While not clang-tidy answer, i wonder if this is an appropriate use-case for
https://clang.llvm.org/docs/ThreadSafetyAnalysis.html

(The following is undested, and is pure speculation)

Have some global symbol, like
typedef int __attribute__((capability("role"))) coroutine_role;
coroutine_role _coroutine_fn;

And then defining:
#define coroutine_fn REQUIRES(_coroutine_fn)

And compiling with -Wthread-safety.

> What would you suggest instead?
>
> PS: forgive me if this is not the clang-tidy list.
> PS2: I opened 2 little bugs on bugzilla, no reply so far
> https://bugs.llvm.org/show_bug.cgi?id=33440,
> https://bugs.llvm.org/show_bug.cgi?id=33441
>
> --
> Marc-André Lureau
Roman.

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