[cfe-dev] Getting RecordDecl from CXXBaseSpecifier

[Richard Smith]

You can also use getType()->getAsCXXRecordDecl(), which is a little more
convenient and also copes with the obscure case of deriving from the
injected-class-name within a class template.

On Mon, May 13, 2013 at 8:20 AM, Justin Arruda <paradoxum at gmail.com> wrote:

> I want to retrieve the Decl so that I may use its isDerivedFrom
> method.  I know that my target class is derived from class A.  I am
> trying to determine which base of class is derived from class A.
>
> My main misunderstanding was not knowing how Decls and Types are
> related.  I believe your solution of using getAs and getDecl is
> precisely what I was looking for!
>
> Thanks
> --
> Justin Arruda
> 401.338.4310
> http://justinarruda.com/
> http://www.linkedin.com/in/justinarruda
>
>
> On Mon, May 13, 2013 at 8:55 AM, Sebastian Redl
> <sebastian.redl at getdesigned.at> wrote:
> >
> > On 13.05.2013, at 06:15, Justin Arruda wrote:
> >
> >> Hello all.  New to cfe-dev (and participating in mailing lists in
> general).
> >>
> >> The question I'm hoping to have answered is as simple as the subject
> >> implies. I have a CXXRecordDecl,
> >> and I am trying to determine which of its bases is derived from a
> >> class that I know this CXXRecordDecl
> >> is also derived from.
> >>
> >> i.e.
> >> class A;
> >> class B : public A;
> >> class C;
> >>
> >> class D : public B, public C
> >> Looking for which base D gets its A from.
> >>
> >> I am also seeking general advice for my project as it pertains to my
> >> usage of clang.  I am using
> >> libtooling and ASTMatchers to create Python bindings for a game engine.
> >>
> >> This is some sample input I am using for my generator: [test-input].
> >>
> >> When attempting to locate which base of MyBaz and MyDerived gets their
> >> inheritance of Colossus::MyBase,
> >> I've tried the following strategy: Obtain the type of the base
> >> specifier, and using an appropriate
> >> DeclContext, look up the declaration.  Once I have the declaration, I
> >> can use its methods to determine if
> >> it's derived from Colossus::MyBase (or is that class).
> >>
> >> // Get the qualified name of the base
> >> QualType type = aBaseSpecifier->getType();
> >> DeclarationName baseDeclName( type.getBaseTypeIdentifier() );
> >>
> >> // Grab a context to look up the decl
> >> const DeclContext* lookupContext = theCxxRecordDecl->getLookupContext();
> >>
> >> DeclContext::lookup_const_result lr =
> lookupContext->lookup(baseDeclName);
> >
> > Looking up the name of the type is too complicated. Also, why do you
> want the decl? If you want to compare for equality, the type is more
> interesting.
> >
> > In any case, the QualType returned by CXXBaseSpecifier::getType() will
> always (perhaps unless you're dealing with a template definition) be a
> RecordType underneath; just use type->getAs<RecordType>() to get the
> RecordType. Then you can use getDecl() on the result, which returns a
> RecordDecl, but in C++ every RecordDecl is a CXXRecordDecl, so you can just
> cast<CXXRecordDecl> it.
> >
> > Sebastian
>
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