rnk added inline comments.

================
Comment at: lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp:1754
+          m_ast.getASTContext(),
+          
clang::MSInheritanceAttr::Spelling::Keyword_unspecified_inheritance));
+    }
----------------
mstorsjo wrote:
> rnk wrote:
> > I'm concerned that this isn't really the right fix. Changing the 
> > inheritance model changes the size of the member pointer representation, so 
> > the consequences of getting the wrong one could affect expression 
> > evaluation results. Zequan suggested guessing the inheritance model from 
> > the class definition, but we really ought to write down the inheritance 
> > model in the DWARF when using the MS ABI. This probably needs its own DWARF 
> > attribute.
> FWIW, there’s two use cases at play here:
> 
> 1. The executable actually is using the itanium ABI, but is being 
> (mis)interpreted with the MSVC ABI. When this happens, we currently crash, 
> which is a terrible user experience. In this case, there’s probably no good 
> solution (we can’t really get it right at this point) - but pretty much 
> anything is better than crashing. Before D127048, we always interpreted 
> everything with the MSVC C++ ABI; now we probably are getting it right in a 
> majority of cases at least.
> 
> 2. People intentionally using dwarf debug into with MSVC ABI. Not very 
> common, but something that some people do use, as far as I know. Here we at 
> least have a chance of getting right.
I see, I thought we already knew we were in use case 2 not 1. Having this as a 
workaround to not crash seems fine, but we really ought to warn when LLDB 
encounters these conditions:
1. MS C++ ABI is in use
2. DWARF is in use
3. A C++ source file is in use

Using DWARF for C code in the MS ABI model is fine, no need to warn in that 
case.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D130942/new/

https://reviews.llvm.org/D130942

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