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

[Alexander Yermolovich via Phabricator via llvm-commits]

ayermolo 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());
+
----------------
dblaikie wrote:
> 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())`
k, will try next week. Thx for helping with this.


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

https://reviews.llvm.org/D132900