Miscompilation: missing assignment in function that might throw

[Brian Green <briangreenery@gmail.com>]

[-- Attachment #1: Type: text/plain, Size: 503 bytes --]

I was unable to create an account in the gcc bugzilla, so I am trying to
report this here.

The following code should always exit with "5". Starting in g++ 12.1, it
will exit with "5" at "-O0" and with random garbage at "-O1" or "-O2".

https://godbolt.org/z/T3qTnheYW

struct Int {
  int value;
};

__attribute__((noipa)) Int always_throws() { throw 123; }

void foo(Int &x) {
  try {
    x = always_throws();
  } catch (...) {
  }
}

int main() {
  Int x;
  x.value = 5;
  foo(x);
  return x.value;
}