[PATCH] D41264: Fix faulty assertion for void type in debug info

[Paul Robinson via Phabricator via llvm-commits]

probinson added a comment.

In https://reviews.llvm.org/D41264#959575, @aprantl wrote:

>   0x00000068:     DW_TAG_typedef
>                     DW_AT_name	("_Nodeptr")
>                     DW_AT_decl_file	("/tmp/t.cpp")
>                     DW_AT_decl_line	(2)
>  
>   0x0000006f:     NULL
>
>
> this also looks weird, but is apparently sort of legal DWARF:
>
> > For example, in C and C++ the language implementation can provide an unspecified type entry with the name “void” which can be referenced by the type attribute of pointer types and typedef declarations for ’void’.
>
> although it would be nicer to use DW_TAG_unspecified_type instead.
>
> Based on this it looks like we should allow this case.


I didn't think it was legal either, but the description of DW_TAG_typedef does say it "may" have a DW_AT_type, and even discusses when it's appropriate to leave it out.

Using `void` as the return type of a subprogram is explicitly represented as omitting DW_AT_type from the subprogram DIE, and that's probably where the nullptr idea came from.

A typedef of `void *`  goes to a DW_TAG_pointer_type which is required to have at DW_AT_type, which I think we do emit as DW_TAG_unspecified_type.  So, for consistency I'd think we might want typedef to do something similar.  But, omitting is legal.


Repository:
  rL LLVM

https://reviews.llvm.org/D41264