Fix for issue #9967 - ParameterIdentifierTuple broken for setters

[yazd]

Fixes http://d.puremagic.com/issues/show_bug.cgi?id=9967

ParameterIdentifierTuple broken for setters

[yazd]

A regression due to commit 877e7bf fixing issue http://d.puremagic.com/issues/show_bug.cgi?id=3646 is causing this pull to fail. I will file a regression bug shortly.

dlang/dmd#1102

Edit: filed a regression bug http://d.puremagic.com/issues/show_bug.cgi?id=10548

[9rnsr]

Currently there's no way to get parameter identifiers from property functions.
You can see the parameters name by pragma(msg, typeof(&prop)), but cannot take them by alias.

@property void prop(int x) {}
pragma(msg, typeof(&prop));   // prints "(int x)"
alias FP = typeof(&prop);
pragma(msg, FP); // prints "(int)" [!]

Right now this is expected behavior. But at the same time this makes fixing bug 9967 impossible.
So, I'm proposing a compiler enhancement (bugzilla issue and PR)

[yazd]

I think that the enhancement is very useful as it serves the purpose without hacks/workarounds. I'm all with it.

However, disregarding this particular issue, I'm not sure whether it is wise to make an alias that is not truly completely aliasing the original symbol. I would say that this is unexpected behaviour.

[9rnsr]

I reconsidered about semantics, and then concluded that we can fix 10548 without any problems. Thank you for the good pointing out.

[yazd]

Thanks for your great efforts and rapid response.

[yazd]

This is all green.
To ease review, the problem with setters was that typeof returned the returned type of the function and so it wouldn't match the first branch. And the second branch which used FunctionTypeOf deliberately silenced the parameter names so as delegates and function pointers are not tied with parameter names.
I changed the first branch to do the check using FunctionTypeOf and then filter out delegates and function pointers to have the intended behaviour.

[9rnsr]

func is 1-length tuple, so you can write like as isFunctionPointer!func and isDelegate!func.

[9rnsr]

LGTM, except one nitpick.

[yazd]

Updated.

[9rnsr]

Thanks!

[yazd]

Thank you!