ChuanqiXu added inline comments.
================
Comment at:
clang-tools-extra/test/clang-tidy/checkers/bugprone/exception-escape-coro.cpp:75-79
+ // CHECK-MESSAGES-NOT: :[[@LINE-1]]:11: warning: an exception may be thrown
in function 'b_ShouldNotDiag' which should not throw exceptions
+ if (b == 0)
+ throw b;
+
+ co_return a / b;
----------------
denizevrenci wrote:
> ChuanqiXu wrote:
> > I don't understand why we shouldn't emit the warning here. Since the
> > function is marked `noexcept` but it may throw actually in
> > `unhandled_exception`. I think it is meaningful to warn for this.
> Right, I now see that this behavior is different between Clang's
> `-Wexceptions` and Clang Tidy's `bugprone-exception-escape`. The former does
> not warn on this code, the latter does.
>
> ```
> int foo() {
> throw 1;
> }
>
> int bar() noexcept {
> return foo();
> }
> ```
>
> We need to treat coroutines differently and check whether `task::task`,
> `promise::promise`, `promise::initial_suspend`,
> `promise::get_return_object`, and `promise::unhandled_exception` can throw
> instead of the body of the coroutine.
I investigated the exception issue in coroutines before:
https://reviews.llvm.org/D108277. And it is much more complex than I thought.
The short conclusion here is that the coroutine is still may throw even if all
the promise's method wouldn't throw. For example:
```
struct Evil {
~Evil() noexcept(false) { throw 32; }
};
task foo() noexcept { // all promise's method of task wouldn't throw
throw Evil;
}
```
And in the above example, foo() may throw actually. Although the implicit
`catch` block of `foo()` will catch `Evil`, the exception in the destructor of
`Evil` will be thrown again.
So we can't be sure that a coroutine wouldn't throw even if all of its
promise's method wouldn't throw.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D147417/new/
https://reviews.llvm.org/D147417
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