[swift-dev] metatype of Int

[Rafkind, Jon]

Yes, context.getIntDecl() was exactly what I was looking for. Thank you Jordan!

On 12/18/2015 08:49 PM, Jordan Rose wrote:
I think Jon's trying to build something on top of swiftc or SourceKit. Yes?

You can do something like this to build your own metatype:

ASTContext &ctx = …
Type intTy = ctx.getIntDecl()->getDeclaredType();
auto *intMetaTy = MetatypeType::get(intTy, ctx);

And then compare types using TypeBase::isEqual (which looks through typealiases and such—it's comparing "canonical" types).

Type unknownTy = …
if (unknownTy->isEqual(intMetaTy)) {
  // celebrate
}

Hope that helps,
Jordan

On Dec 18, 2015, at 13:47 , Slava Pestov via swift-dev <swift-dev at swift.org<mailto:swift-dev at swift.org>> wrote:

You can probably get the mangled name of the metatype, and refer to that. Eg,

public func f() -> Any.Type {
 return Int.self
}

f()

Compile this with -emit-ir:

@_TMSi = external global %swift.type, align 8

define %swift.type* @_TF4blah1fFT_PMP_() #0 {
entry:
 ret %swift.type* @_TMSi
}

So in your C++ program,

extern "C" {
 extern void *_TMSi;
}

Note that this is completely unsupported, and probably insane. You have been warned.

Slava

On Dec 18, 2015, at 12:14 PM, Rafkind, Jon via swift-dev <<mailto:swift-dev at swift.org>swift-dev at swift.org<mailto:swift-dev at swift.org>> wrote:

Sorry I should have been more specific. I am working at the C++ level. I have a swift::MetaType* and want to compare it to something.

On 12/18/2015 12:10 PM, Dave Abrahams wrote:




On Dec 18, 2015, at 11:16 AM, Rafkind, Jon via swift-dev <swift-dev at swift.org<mailto:swift-dev at swift.org>><<mailto:swift-dev at swift.org>mailto:swift-dev at swift.org> wrote:

Given a swift::MetaType how can I tell if it corresponds to the MetaType of the standard Int type? Is there a way to get a reference to the MetaType from the StdlibModule or TheBuiltinModule?

For now I can convert the MetaType to a string and compare it to "Int.Type" but that is yucky.



Equality comparison works:

(swift) String.self == Int.self
// r2 : Bool = false
(swift) Int.self == Int.self
// r3 : Bool = true





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-Dave






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