[cfe-dev] CXCursor_CXXBaseSpecifier for template instantiated base class

Thu Mar 16 10:10:10 PDT 2017

Hi Nestal,

I am not sure if I understood you correctly but you want to find out the
structure/hierarchy of your "Derived" class, that is all of the base
classes that your derived class is inheriting from? If this is what you are
asking for, then you can accomplish this by enumerating all of the
`CXCursor_TypeRef`'s of corresponding `CXCursor_CXXBaseSpecifier` cursors
which are descendants (children) of class declaration (`CXCursor_ClassDecl`)
which you're interested in (i.e. "Derived").

When parser is run on your example, `CXCursor_CXXBaseSpecifier` cursors are
`RecursiveBase<class Base>`, `class Base2` and `class Base3`. Corresponding
`CXCursor_TypeRef` cursors are `class Base`, `class Base2` and `class Base3`.
This is what I believe you're looking for.

For a generic and full-proof solution, you will want to do the same thing
recursively for each `CXCursor_CXXBaseSpecifier` found.

Cheers,
Adi

On 14 March 2017 at 17:39, Nestal Wan <me at nestal.net> wrote:

> Thanks Adi,
>
> Like you said, I solve the problem by fixing the errors that were
> indicated by the diagnostic messages.
>
> Now I have another question, if you don't mind I keep using this thread.
>
> I wish know the class hierarchy of "Derived". That means getting the
> base class the the instantiated RecursiveBase<Base> template. That
> should be "Base".
>
> When I visit "Dervied", I got a cursor to a CXCursor_CXXBaseSpecifier.
> I tried to get the type by:
>
> CXType recursive_base =
> clang_getCursorType(clang_getCursorDefinition(cxx_base_specifier));
>
> "recursive_base" refers to the RecursiveBase<Base> instantiation. How
> can I get the base type of this class? I know I can get the cursor to
> the template that instantiate it (i.e. template <typename BaseType>
> RecursiveBase), and I can see it inherits "BaseType" by visiting it
> and look for CXCursor_CXXBaseSpecifier. But how can I know "BaseType"
> will become "Base" when we instantiate it? Will the CXType provides me
> this linkage or I need to use LibTooling instead?
>
> Thanks again.
>
> Nestal
>
> On Sun, Mar 12, 2017 at 9:25 PM, Jusufadis Bakamovic <jbakam at gmail.com>
> wrote:
> > It is hard to tell without more context why you're getting this error,
> but
> > my guess is that you're missing some command line args (i.e. include
> paths,
> > preprocessor flags, etc.) which is specific to the code you're analyzing
> and
> > which is required in order to get the parsing stage done right. Very
> often
> > this is the case and which is why you should, whenever you have doubts,
> > always try to come up with a small reproducible example (without
> > dependencies) and have it validated separately.
> >
> > Additionally, you can try to extract diagnostics for the given
> translation
> > unit and see if you get any hints there. Normally, you should get hints
> if
> > clang parser was not able to fully parse the source code because it was
> > missing some information such as failing to find particular headers.
> >
> > Cheers,
> > Adi
> >
> > On 12 March 2017 at 10:13, Nestal Wan <me at nestal.net> wrote:
> >>
> >> Thanks for the reply.
> >>
> >> -CXXRecordDecl 0x55e6db0f5ad8 <line:53:1, line:59:1> line:53:7 invalid
> >> class
> >> Derived definition
> >>
> >> | |-public 'class Base2'
> >> | |-public 'class Base3'
> >> | |-CXXRecordDecl 0x55e6db0f5df8 <col:1, col:7> col:7 implicit
> referenced
> >>
> >> class Derived
> >>
> >> | |-AccessSpecDecl 0x55e6db0f5e88 <line:55:1, col:7> col:1 public
> >> | |-CXXConstructorDecl 0x55e6db0f5ef0 <line:56:2, col:20> col:2 Derived
> >> 'void
> >>
> >> (void)' noexcept-unevaluated 0x55e6db0f5ef0
> >>
> >> | `-CXXMethodDecl 0x55e6db0f5fd0 <line:58:2, col:24> col:7 Func 'void
> >> (void)'
> >> | `-CompoundStmt 0x55e6db0f6118 <col:23, col:24>
> >>
> >>
> >> Sometimes I got "invalid class Derived definition", but if I extract the
> >> classes in another source file, the result is different:
> >>
> >> |-CXXRecordDecl 0x55ccfcb583b0 <line:33:1, line:39:1> line:33:7 class
> >> Derived
> >>
> >> definition
> >>
> >> | |-public 'RecursiveBase<class Base>':'class RecursiveBase<class Base>'
> >> | |-public 'class Base2'
> >> | |-public 'class Base3'
> >> | |-CXXRecordDecl 0x55ccfcb58c70 <col:1, col:7> col:7 implicit
> referenced
> >>
> >> class Derived
> >>
> >> What does it mean the class definition is invalid? There is no compile
> >> error.
> >>
> >> Nestal
> >>
> >> On Sun, Mar 12, 2017 at 4:46 PM, Jusufadis Bakamovic <jbakam at gmail.com>
> >> wrote:
> >> > You should be getting three times the `CXCursor_CXXBaseSpecifier`, one
> >> > for
> >> > each class you're inheriting from. I ran the analysis on my machine
> >> > (clang
> >> > 3.8) and that is exactly what I am getting: `RecursiveBase<class
> Base>`,
> >> > `Base2`, `Base3`. Maybe you could use `clang -Xclang -ast-dump
> >> > -fsyntax-only
> >> > <this_demo>` to see the output of Clang's built-in AST dumper. It
> should
> >> > contain these entries. Otherwise, clang version you're running might
> be
> >> > an
> >> > older one.
> >> >
> >> > On 12 March 2017 at 05:09, Nestal Wan via cfe-dev
> >> > <cfe-dev at lists.llvm.org>
> >> > wrote:
> >> >>
> >> >> Hi,
> >> >>
> >> >> When I use clang_visitChildren() to visit a class, I can't get a
> >> >> CXCursor_CXXBaseSpecifier for its base class if the base class is a
> >> >> template. For example:
> >> >>
> >> >> template <typename BaseType>
> >> >> class RecursiveBase : public BaseType
> >> >> {
> >> >> public:
> >> >>    virtual void SomeFunc()
> >> >>    {
> >> >>       // prevent optimizer to remove the function
> >> >>       global_var++;
> >> >>    }
> >> >> };
> >> >>
> >> >> class Derived : public RecursiveBase<Base>, public Base2, public
> Base3
> >> >> {
> >> >> public:
> >> >>    Derived() = default;
> >> >>
> >> >>    void Func() override {}
> >> >> };
> >> >>
> >> >> I can get a CXCursor_CXXBaseSpecifier cursor as children of the
> >> >> "Derived" cursor, but not RecursiveBase. How can I find out
> references
> >> >> to all base classes including templates?
> >> >>
> >> >> Thanks.
> >> >>
> >> >> Nestal
> >> >> _______________________________________________
> >> >> cfe-dev mailing list
> >> >> cfe-dev at lists.llvm.org
> >> >> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev
> >> >
> >> >
> >
> >
>
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