[swift-dev] Unexpected Expr type

[Halen Wooten]

Ah, that makes sense.

Thanks so much to you both for helping out. Hopefully I'll have a PR
ready before too long!

On Thu, Apr 6, 2017 at 7:11 PM, Halen Wooten <halen at hpwooten.com> wrote:
> Ah, that makes sense.
>
> Thanks so much to you both for helping out. Hopefully I'll have a PR
> ready before too long!
>
> Halen
>
> On Thu, Apr 6, 2017 at 7:05 PM, Slava Pestov <spestov at apple.com> wrote:
>> Here’s what the AST looks like in this case — there is a ParenExpr but it’s inside a LoadExpr — we’re semantically loading the largest sub-expression that’s an lvalue, which here is ‘(x)’ not ‘x’:
>>
>>       (assign_expr
>>         (declref_expr type='@lvalue Int' accessKind=write location=x.swift:3:1 range=[x.swift:3:1 - line:3:1] decl=x.(file).v at x.swift:1:5 direct_to_storage function_ref=unapplied specialized=no)
>>         (load_expr implicit type='(Int)' location=x.swift:3:6 range=[x.swift:3:5 - line:3:7]
>>           (paren_expr type='(@lvalue Int)' accessKind=read location=x.swift:3:6 range=[x.swift:3:5 - line:3:7]
>>             (declref_expr type='@lvalue Int' accessKind=read location=x.swift:3:6 range=[x.swift:3:6 - line:3:6] decl=x.(file).v at x.swift:1:5 direct_to_storage function_ref=unapplied specialized=no)))))))
>>
>> Slava
>>
>>> On Apr 6, 2017, at 4:02 PM, Halen Wooten via swift-dev <swift-dev at swift.org> wrote:
>>>
>>> Hi Jordan,
>>>
>>> Thanks for your reply. I tried the `dyn_cast<ParenExpr>(src)`, but it
>>> gives me null. Here's what I've added:
>>>
>>> bool TypeChecker::diagnoseSelfAssignment(const Expr *E) {
>>>
>>>  ...
>>>
>>>  auto src = AE->getSrc();
>>>  auto parenSrc = dyn_cast<ParenExpr>(src);
>>>  if (parenSrc)
>>>    return false;
>>>
>>> ...
>>>
>>> }
>>>
>>>
>>>
>>> On Thu, Apr 6, 2017 at 6:49 PM, Jordan Rose <jordan_rose at apple.com> wrote:
>>>> Hi, Halen. Welcome to the compiler. :-) What you're seeing is that we don't
>>>> usually use C++'s normal RTTI mechanism, but instead go with a "Kind" field
>>>> that's checked by the custom 'cast', 'dyn_cast', and 'isa' functions. (More
>>>> information in the LLVM Programmer's Manual.) The debugger doesn't know
>>>> about this, so it just always shows the base class to be conservative. If
>>>> you're debugging, you can call dump() to see what kind of Expr it really is,
>>>> and then cast the pointer down to the right type as needed. In your actual
>>>> code, you can check `isa<ParenExpr>(src)`, or `dyn_cast<ParenExpr>(src)` if
>>>> you then need to manipulate the ParenExpr.
>>>>
>>>> Hope that helps,
>>>> Jordan
>>>>
>>>>
>>>> On Apr 6, 2017, at 15:30, Halen Wooten via swift-dev <swift-dev at swift.org>
>>>> wrote:
>>>>
>>>> Hi swift devs,
>>>>
>>>> I'm working on SR-4464 to learn how to contribute to Swift. I think I
>>>> have the solution, but I'm getting unexpected results.
>>>>
>>>> I'm using the swift repl within Xcode for testing. Here's my test code.
>>>>
>>>> var name = "name"
>>>> name = (name)
>>>>
>>>> In TypeChecker::diagnoseSelfAssignment in CSDiag.cpp, the src of the
>>>> AssignExpr is a plain Expr *, but I would expect it to be a ParenExpr
>>>> *. Could someone help me figure out what's happening?
>>>>
>>>> Thanks,
>>>> Halen
>>>> _______________________________________________
>>>> swift-dev mailing list
>>>> swift-dev at swift.org
>>>> https://lists.swift.org/mailman/listinfo/swift-dev
>>>>
>>>>
>>> _______________________________________________
>>> swift-dev mailing list
>>> swift-dev at swift.org
>>> https://lists.swift.org/mailman/listinfo/swift-dev
>>