Allow inspect statements

[ntrel]

I'm not sure why they were disabled, the test below works.

Update: A small fix was needed to avoid emitting }; else Cpp1 when statement is a compound statement.

[JohelEGP]

Does this also resolve #723?
If so, add "Closes #723" to the opening comment.

[JohelEGP]

Is this the correct implementation?
I don't think there's code to lower inspect statements.
What happens with this code?

main: () = {
  inspect 0 {
    is 0 = std::cout << "0\n";
    is _ = std::cout << "?\n";
  }
}

In the test case, the inspect is actually the expression of an expression-statement.
Could it be that is_expression should have been true in this case?

[ntrel]

Oh that doesn't work. So yes it seems the test case is doing return inspect v {.

It does work actually!

[ntrel]

I don't think there's code to lower inspect statements.

There is, in emit(inspect_expression_node, bool). If is_expression is false, the lambda parameters and inline call are not emitted, but the braces still are emitted. So it just generates a block. You can see it in the diff here.

[ntrel]

While your example does work, the following does not:

  inspect 0 {
    is 0 = { std::cout << "0\n"; }
    is _ = std::cout << "?\n";
  }

The Cpp1 code has a semi-colon before the else clause, causing an error. I'll try to fix it.

[JohelEGP]

Maybe you should scope your PR
to treating inspect as an expression rather than as a statement
when it is a declaration's statement.

[ntrel]

Now pushed a simple fix.

[ntrel]

Does this also resolve #723?

No, it gives:

    s := inspect v -> std::string {

inspect.cpp2(13,20): error: an inspect statement cannot have an explicit return type (whereas an inspect expression must have one) (at '->')