Please confirm which libabigail version the stack backtrace corresponds to. Thanks!

Based on IRC, it sounds like it was current master.
fd8640dc09b99bee11745a4d5b176b2dee3400f4

Another question, does your source contain any forward-declared enums?

(approximately) grep -w 'enum *[A-Za-z0-9_]*;'

Yes, you deduced the correct commit for the stacktrace :)

And yes, there is a single 'enum class Foo;' in the public API.

Regarding the forward declared enum:

The layout is:

A.h:
```
enum class Foobar;
```

Abstract.h:
```
#include "A.h"
enum class Foobar {
  A, B, C;
};

class Abstract {

public:
   void pure() = 0;
   Foobar somefunc();
private:
   Foobar member;
};
```

All that is contained in the library.
But there is no implementation of Abstract inside the lib!

Thank you for reporting this issue, and sorry for the inconvenience.

Looking at the backtrace it looks like libabigail the segmentation fault is happening on this line:

··if·(*l.get_underlying_type()·!=·*r.get_underlying_type())$  


basically, l and r are typdef types.  Normally, {l,r}.get_underlying_type() can never be NULL, because typedef always have underlying types.

So I am not sure what is happening there.  It would be really helpful if I could look at the binary itself to see what is happening, but I guess that is not possible, is it?

Just for the record, the git hash I am looking at is this one: fd8640dc09b99bee11745a4d5b176b2dee3400f4

Hey. Sorry for the late reply but vacation happened.

Sadly i can't attach the binary here but I'd be happy to help debug it. My attempts to create a test case failed so far..

A bit more info:

- still happens in current master ( ebaf3305 )
- is unrelated to any actual change, comparing the same bins/includes crashes
- only crashes if called with '--drop-private-types'


$ ./bin/abidiff /path/to/lib.so /path/to/lib.so --hd1 /path/to/hdr --hd2 /path/to/hdr
$ ./bin/abidiff --drop-private-types /path/to/lib.so /path/to/lib.so --hd1 /path/to/hdr --hd2 /path/to/hdr
Segmentation fault (core dumped)

at same location:

#0  abigail::ir::equals (l=..., r=..., k=0x0) at ../../src/abg-ir.cc:15819
#1  0x00007ffff7c456d9 in abigail::ir::try_canonical_compare<abigail::ir::typedef_decl> (l=0x555557a18710, r=0x555555e1d8b0) at ../../src/abg-ir.cc:670
#2  0x00007ffff7c0efc6 in abigail::ir::typedef_decl::operator== (this=0x555557a18710, o=...) at ../../src/abg-ir.cc:15842
#3  0x00007ffff7c0f041 in abigail::ir::typedef_decl::operator== (this=0x555557a18710, o=...) at ../../src/abg-ir.cc:15857
#4  0x00007ffff7be9204 in abigail::ir::operator== (l=std::shared_ptr<abigail::ir::type_base> (use count 4, weak count 11) = {...}, r=std::shared_ptr<abigail::ir::type_base> (use count 9, weak count 10) = {...}) at ../../src/abg-ir.cc:4322
#5  0x00007ffff7c0114c in abigail::ir::type_base::get_canonical_type_for (t=std::shared_ptr<abigail::ir::type_base> (use count 9, weak count 10) = {...}) at ../../src/abg-ir.cc:12178
#6  0x00007ffff7c01808 in abigail::ir::canonicalize (t=std::shared_ptr<abigail::ir::type_base> (use count 9, weak count 10) = {...}) at ../../src/abg-ir.cc:12301
#7  0x00007ffff7dfa1b1 in abigail::dwarf_reader::read_context::canonicalize_types_scheduled (this=0x555565bc2f50, source=abigail::dwarf_reader::PRIMARY_DEBUG_INFO_DIE_SOURCE) at ../../src/abg-dwarf-reader.cc:4833
#8  0x00007ffff7dfa9b6 in abigail::dwarf_reader::read_context::perform_late_type_canonicalizing (this=0x555565bc2f50) at ../../src/abg-dwarf-reader.cc:4949
#9  0x00007ffff7deb4c7 in abigail::dwarf_reader::read_debug_info_into_corpus (ctxt=...) at ../../src/abg-dwarf-reader.cc:16024
#10 0x00007ffff7df00f6 in abigail::dwarf_reader::read_corpus_from_elf (ctxt=..., status=@0x7fffffffd05c: abigail::dwarf_reader::STATUS_UNKNOWN) at ../../src/abg-dwarf-reader.cc:17149
#11 0x0000555555559c15 in main (argc=<optimized out>, argv=0x7fffffffd488) at /usr/include/c++/10.2.0/bits/shared_ptr_base.h:1324