On Monday, 21 February 2022 at 11:11:28 UTC, partypooper wrote:

I'm not sure what you mean. If a function throws an exception, it can't be nothrow.

Function attribute inference is done in specific circumstances, but not for all functions. See https://dlang.org/spec/function.html#function-attribute-inference.

On Monday, 21 February 2022 at 11:07:55 UTC, Basile B. wrote:

This has nothing to do with which exceptions types a function throws. The compiler doesn't dig into that. You have to catch Exception.

import std.stdio;

class MyException : Exception {
    this(string msg) { super(msg); }
}

void throwing(int x) {
    if(x > 2) throw new MyException("Derp!");
    else writeln(x);
}

void noThrowing() nothrow {
    try {
        throwing(10);
    }
    catch(MyException me) {}
}

void main()
{
    noThrowing();
}

onlineapp.d(14): Error: function `onlineapp.throwing` is not `nothrow`
onlineapp.d(12): Error: `nothrow` function `onlineapp.noThrowing` may throw

On Monday, 21 February 2022 at 11:12:38 UTC, partypooper wrote:

if nothrow fails that's because things are checked. We could imagine a second flow analysis leading to better error messages. You see, instead of the generic error message you get now.

"If it fails, let's see why"

On Monday, 21 February 2022 at 11:21:52 UTC, Mike Parker wrote:

import std.stdio;

class MyException : Exception {
    this(string msg) { super(msg); }
}

void throwing(int x) {
    if(x > 2) throw new MyException("Derp!");
    else writeln(x);
}

void noThrowing() nothrow {
    try {
        throwing(10);
    }
    catch(MyException me) {}
}

void main()
{
    noThrowing();
}

onlineapp.d(14): Error: function `onlineapp.throwing` is not `nothrow`
onlineapp.d(12): Error: `nothrow` function `onlineapp.noThrowing` may throw

Thank You for detailed explanation.

On Monday, 21 February 2022 at 10:57:07 UTC, Basile B. wrote:

nothrow void hello() {
  try {
    writeln("Hello, World!")
  } catch (StdioException) {}
}

nothrow void hello() {
  try {
    writeln("Hello, World!")
  } catch (Exception) {}
}

What if we could do ex. this:

__traits(possibleExceptions, writeln);

Which would give all exceptions a function could possibly throw.

That way we could build our try/catch based on that.

For nothrow it should return nothing of course, for extern functions that have no source code available it should only return "Exception" of course.

Just a thought I just had.