Bug 13575 – Unreachable scope(failure) should be warned

From issue 11574: import std.stdio; void someFunc() { scope(failure) { writeln("What?");} // <-- never executed. scope(failure) { writeln("Failed in someFunc()"); return; } throw new Exception("Exception!"); } void main() { try { someFunc(); writeln("Yay, someFunc() is nothrow"); } catch(Exception e) { writeln("An exception in main!"); } } In someFunc, the first scope(failure) is never executed. There's no bug, but I think, if -w specified, dmd should warn the code as that it is not reachable.

Your example is pretty good, but not good enough as it introduces other issue, that prevents compiler from optimizing it properly. The writeln("Failed in someFunc()") can fail with the exception (i.e. if the stdout was a pipe into other process, and that process died, or it was redirected to a file, and there was IO error or disk is full / out of quota, just some examples)! And then the first scope(failure) which can in fact execute! Better example: ``` int i = 0; size_t f(string x) nothrow { scope(failure) { i = 5; return 30; } scope(failure) { i = 10; return 42; } throw new Exception("a"); } int main(string[] args) { return cast(int)f(args[0]) + i*i; } ``` Notice that I also added `nothrow` and made scopes use code that can't throw on its own. The compiler doesn't even recognize that the first `scope(failure)` is not dead code. I still see it in the disassembly of the binary. When I run the code it does return 142, as expected. If I change the code to: ``` int i = 0; size_t f(string x) nothrow { scope(failure) { i = 5; return 30; } scope(failure) { i = 10; throw new Exception("b"); } throw new Exception("a"); } int main(string[] args) { return cast(int)f(args[0]) + i*i; } ``` The code correctly returns 55.

Ah, obviously I did forgot to mention that compiler does not warn about my first example. But it should.

You can no longer return from scope(failure)