[PATCH] D132900: [DWARF] Fix infinite recursion in Type Printer.

[David Blaikie via Phabricator via llvm-commits]

dblaikie added inline comments.


================
Comment at: llvm/lib/DebugInfo/DWARF/DWARFTypePrinter.cpp:289-290
 void DWARFTypePrinter::appendQualifiedName(DWARFDie D) {
-  if (D)
+  if (D && !ScopelessDIEs.count(D.getTag()))
     appendScopes(D.getParent());
+
----------------
ayermolo wrote:
> dblaikie wrote:
> > Might be inclined to use a switch here, rather than a set lookup - and it's probably easier to make a positive list of the things that are scoped than those that aren't.
> Unfortunately this doesn't work for:
> 
> ```
> class codecvt_base
> {
>   public:
>     enum result {
>       ok
>     };
> };
> 
> class __codecvt_abstract_base
>     : public codecvt_base
> {
>     public:
>       result out(const wchar_t* __from) const {
>       return result::ok;
>       }
>     };
> 
>     class codecvt
>     : public __codecvt_abstract_base{};
> 
>     inline bool
>     __str_codecvt_out()
>     {
>       using _Codecvt = codecvt;
>       using _ConvFn = codecvt_base::result
>     (_Codecvt::*)(const wchar_t*) const;
>       _ConvFn __fn = &codecvt::out;
>       return true;
>     }
> 
> bool test() {
>     return __str_codecvt_out();
> }
> ```
> 
> It prints out this before eventually crashing.
> 0x00000133:       DW_TAG_formal_parameter [8]   (0x00000126)
>                     DW_AT_type [DW_FORM_ref4] (cu + 0x0138 => {0x00000138} "codecvt_base::result (codecvt_base::result (codecvt_base::result (codecvt_base::result (codecvt_base::result (codecvt_base::result (codecvt_base::result (codecvt_base::result (codecvt_base::result (codecvt_base::result (::codecvt_base::result (::const _Codecvt *::codecvt_base::result (::const _Codecvt *::codecvt_base::result (::const _Codecvt *::codecvt_base::result (::const _Codecvt *::codecvt_base::result (::const _Codecvt *::codecvt_base::result (::const _Codecvt *::codecvt_base::result (::const _Codecvt *::codecvt_base::result (::const _Codecvt *::codecvt_base::result (::const _Codecvt *::codecvt_base::result (::const _Codecvt *")
> 
> 
> Maybe better approach is to apply this allow list approach to DWARFTypePrinter::appendScopes? So it will return unless it's one of those TAGs.
I don't think it'd work to do this in `appendScopes` because `appendScopes` gets passed the scope, not the thing that's being scoped - and the determination on whether to skip scopes should be on the type being scoped, not the scoping.

Could you reduce the test down a bit - help understand what's interesting about this? I guess there's some other place that appends scopes that needs handling? Looks like the only other uses is `appendQualifiedNameBefore` - so I guess the handling needs to be in both of those, which sounds plausible/reasonable.

But yeah, maybe sinking a wrapper. `appendQualification` or something, which just does the `if (D) / check the type, then appendScopes(D.getParent())`


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D132900/new/

https://reviews.llvm.org/D132900