llvm dev - Oct 2019 - Upgrading LLVM API versions, trouble with DIVariable

Hello,

I am working on upgrading LLVM libraries from 3.0 to 7.0.0 for a project to
be compatible with an outside project.

I've made good progress but am running into a wall for all things related
to DIVariables and there creation from existing Metadata objects.

Specifically I've run into 3 issues;

(1)I am trying to create a DIType from the Type of an existing DIVariable
using getType().

foo (DIVariable& oldDIVar){

    const DIType oldDIType = oldDIVar.getType();
}

According to the llvm documentation, DIVariable::getType should return a
DIType*. But I get an error message:

error: no viable conversion from 'llvm::DITypeRef' (aka
'TypedDINodeRef<llvm::DIType>') to 'const llvm::DIType *'
  const DIType *oldDIType = oldDIVar.getType();
                ^           ~~~~~~~~~~~~~~~~~~

I've messed around with dereferencing the oldDIVar variable, which points
to the underlying Metadata of it. I would assume that attempting to create
a DIType from pure metadata would be fine, since it inherits from the
metadata class. But I always get the error:

 error: no viable conversion from 'llvm::Metadata' to
'llvm::DIType'
  DIType oldDIType = *oldDIVar.getType();
         ^           ~~~~~~~~~~~~~~~~~~~
/root/llvm-7.0.0/include/llvm/IR/DebugInfoMetadata.h:630:7: note: candidate
constructor (the implicit copy constructor) not viable: cannot bind base
class object of type 'llvm::Metadata' to derived class
      reference 'const llvm::DIType &' for 1st argument
class DIType : public DIScope {

Am I missing something about inheritance that prevents this?

(2)One of the other errors is similar;

  Unable to convert from MDNode to DIVariable

(3)The final one is strange to me. Once again trying to make a DIVariable
from and oldDIVar,
this time calling DbgVariables::getVariables(). I try to call it as such;

DIVariable oldDIVar(*(oldDeclare->getVariable());

But that seems to give an error due to an implicitly deleted copy
constructor, which completely baffles me.

error: call to implicitly-deleted copy constructor of 'llvm::DIVariable'
                  DIVariable oldDIVar(*(oldDeclare->getVariable()));


If anyone could provide insight into why creating DIVariables and DITypes
is failing, and what the implicitly deleted copy constructor is being
caused by, I'd really appreciate it.

This is my first time using this mailing list, so apologies of I made a
mistake somewhere.

Regards,

Trevor
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.llvm.org/pipermail/llvm-dev/attachments/20191008/ebaf0043/attachment.html>

Hi,

On Tue, Oct 08, 2019 at 06:23:04PM +0000, Trevor Martin via llvm-dev
wrote:
> Hello,
>
> I am working on upgrading LLVM libraries from 3.0 to 7.0.0 for a project to
> be compatible with an outside project.
>
> I've made good progress but am running into a wall for all things
related
> to DIVariables and there creation from existing Metadata objects.
>
> Specifically I've run into 3 issues;
>
> (1)I am trying to create a DIType from the Type of an existing DIVariable
> using getType().
>
> foo (DIVariable& oldDIVar){
>
>     const DIType oldDIType = oldDIVar.getType();
> }
>
> According to the llvm documentation, DIVariable::getType should return a
> DIType*. But I get an error message:
It does these days, but back in 7.x it returned the TypedDINodeRef you
see. It's an ugly API, but you need to use the `resolve` method to get
the actual `T*` out.
> error: no viable conversion from 'llvm::DITypeRef' (aka
> 'TypedDINodeRef<llvm::DIType>') to 'const llvm::DIType
*'
>   const DIType *oldDIType = oldDIVar.getType();
>                 ^           ~~~~~~~~~~~~~~~~~~
>
> I've messed around with dereferencing the oldDIVar variable, which
points
> to the underlying Metadata of it. I would assume that attempting to create
> a DIType from pure metadata would be fine, since it inherits from the
> metadata class. But I always get the error:
>
>  error: no viable conversion from 'llvm::Metadata' to
'llvm::DIType'
>   DIType oldDIType = *oldDIVar.getType();
>          ^           ~~~~~~~~~~~~~~~~~~~
> /root/llvm-7.0.0/include/llvm/IR/DebugInfoMetadata.h:630:7: note: candidate
> constructor (the implicit copy constructor) not viable: cannot bind base
> class object of type 'llvm::Metadata' to derived class
>       reference 'const llvm::DIType &' for 1st argument
> class DIType : public DIScope {
>
> Am I missing something about inheritance that prevents this?
>
> (2)One of the other errors is similar;
>
>   Unable to convert from MDNode to DIVariable
Out of context it's hard for anyone to work anything out. Clearly you
have an MDNode somewhere where a DIVariable is expected, so you should
work out why that is and what you're meant to do about it? But it sounds
like it's related to (3).
> (3)The final one is strange to me. Once again trying to make a DIVariable
> from and oldDIVar,
> this time calling DbgVariables::getVariables(). I try to call it as such;
>
> DIVariable oldDIVar(*(oldDeclare->getVariable());
>
> But that seems to give an error due to an implicitly deleted copy
> constructor, which completely baffles me.
>
> error: call to implicitly-deleted copy constructor of
'llvm::DIVariable'
>                   DIVariable oldDIVar(*(oldDeclare->getVariable()));
See r234263:

    DebugInfo: Drop dead code for loose DIDescriptor construction API

    Delete `DIDescriptor::is*()` and the various constructors from `MDNode*`
    in `DIDescriptor` subclasses.

    If this just broke your out-of-tree code, you need to make updates along
    the lines of r234255, r234256, r234257 and r234258:

      - Generally, `DIX().isX()` => `isa<MDX>()`.  So,
`D.isCompileUnit()`
        should just be `isa<MDCompileUnit>(D)`, modulo checks for null.
          - Exception: `DILexicalBlock` => `MDLexicalBlockBase`.
          - Exception: `DIDerivedType` => `MDDerivedTypeBase`.
          - Exception: `DICompositeType` => `MDCompositeTypeBase`.
          - Exception: `DIVariable` => `MDLocalVariable`.
      - Note that (e.g.) `DICompileUnit` has an implicit constructor from
        `MDCompileUnit*`.

    llvm-svn: 234263

James
> If anyone could provide insight into why creating DIVariables and DITypes
> is failing, and what the implicitly deleted copy constructor is being
> caused by, I'd really appreciate it.
>
> This is my first time using this mailing list, so apologies of I made a
> mistake somewhere.
>
> Regards,
>
> Trevor