[libcxxabi][Demangle] Don't drop ctor/dtor name for abi-tagged structures

Before this patch we would demangle abi-tagged structures as follows:
```
$ c++filt -n _ZN1SB5OuterC2Ev
S[abi:Outer]:()

$ c++filt -n _ZN1SB5OuterD2Ev
S[abi:Outer]::~()
```

This is because `Node::getBaseName` was unimplemented for the
`AbiTagAttr` node, which meant that when we tried printing `CtorDtorName`
where its `Basename` `Node` was an `AbiTagAttr`, we'd drop the
name.

Addresses https://github.com/llvm/llvm-project/issues/61213

Differential Revision: https://reviews.llvm.org/D145492

1 files changed, 2 insertions, 0 deletions

diff --git a/libcxxabi/test/test_demangle.pass.cpp b/libcxxabi/test/test_demangle.pass.cpp
index 0607c4ef7efa..00592eede9a1 100644
--- a/libcxxabi/test/test_demangle.pass.cpp
+++ b/libcxxabi/test/test_demangle.pass.cpp
@@ -30112,6 +30112,8 @@ const char* cases[][2] =
      "::basic_ostream()"},
     {"_ZNSsC1Ev", "std::basic_string<char, std::char_traits<char>,"
      " std::allocator<char>>::basic_string()"},
+    {"_ZN1SB8ctor_tagC2Ev", "S[abi:ctor_tag]::S()"},
+    {"_ZN1SB8ctor_tagD2Ev", "S[abi:ctor_tag]::~S()"},
 };
 
 const unsigned N = sizeof(cases) / sizeof(cases[0]);