[demangler] Fold expressions of .* and ->*

[urnathan]

Summary

(Exitingly) a fold expression's operators include .* and ->*, but we failed to demangle them as we categorize those as MemberExprs, not BinaryExprs.

There is existing practice in the demangler to go looking at the actual token to perform specific actions, hence the peeking of the '*' char to distingish between MemberExpr alternatives here.

[urnathan]

rebase & ping?

[dblaikie]

Sounds OK to me.

libcxxabi/src/demangle/ItaniumDemangle.h

case 'l':
     IsLeftFold = true;
     break;
   case 'r':
     break;
   }
   ++First;
 
   const auto *Op = parseOperatorEncoding();
-  if (!Op || Op->getKind() != OperatorInfo::Binary)
+  if (!Op)
+    return nullptr;
+  if (!(Op->getKind() == OperatorInfo::Binary
+        || (Op->getKind() == OperatorInfo::Member
+            && Op->getName().back() == '*')))
     return nullptr;
 
   Node *Pack = getDerived().parseExpr();
   if (Pack == nullptr)
     return nullptr;
 
   Node *Init = nullptr;
   if (HasInitializer) {

libcxxabi/test/test_demangle.pass.cpp

//    {"_Z1fM1XRFivEMS_OFivEMS_KOFivE", "f(int (X::*)() &, int (X::*)() &&, int (X::*)() const &&)"},
     {"_Z6foldl1IJLi1ELi2ELi3EEEv1AIXfLplLi1ET_EE", "void foldl1<1, 2, 3>(A<(1 + ... + (1, 2, 3))>)"},
     {"_Z6foldr1IJLi1ELi2ELi3EEEv1AIXfRplT_Li1EEE", "void foldr1<1, 2, 3>(A<((1, 2, 3) + ... + 1)>)"},
     {"_Z5foldlIJLi1ELi2ELi3EEEv1AIXflplT_EE", "void foldl<1, 2, 3>(A<(... + (1, 2, 3))>)"},
     {"_Z5foldrIJLi1ELi2ELi3EEEv1AIXfrplT_EE", "void foldr<1, 2, 3>(A<((1, 2, 3) + ...)>)"},
     {"_ZN7PartialIJLi1ELi2EEE5foldrIJLi3ELi4EEEEv1AIXplLi1EplLi2EfRplT_plLi1EplLi2EfrplT_EE",
      "void Partial<1, 2>::foldr<3, 4>(A<1 + (2 + ((3, 4) + ... + (1 + (2 + ((3, 4) + ...)))))>)"},
     {"_ZN7PartialIJLi1ELi2EEE5foldrIJLi3ELi4EEEEv1AIXplplLi1ELi2EfRplT_plplLi1ELi2EflplT_EE",
      "void Partial<1, 2>::foldr<3, 4>(A<1 + 2 + ((3, 4) + ... + (1 + 2 + (... + (3, 4))))>)"},
+    {"_Z1fIXfLpm1x1yEEvv", "void f<(x ->* ... ->* (y...))>()"},
+    {"_Z1fIXfLds1x1yEEvv", "void f<(x .* ... .* (y...))>()"},
 
     // reference collapsing:
     {"_Z1fIR1SEiOT_", "int f<S&>(S&)"},
     {"_Z1fIJR1SS0_EEiDpOT_", "int f<S&, S>(S&, S&&)"},
 
     {"___Z3foo_block_invoke.25", "invocation function for block in foo"},
 
     // Darwin adds leading underscores to symbols, just demangle them anyways.
// The following test cases were found by libFuzzer+ASAN
     "_ZN3TPLS_E",
     "_ZN3CLSIiEIiEE",
     "_ZN3CLSDtLi0EEE",
     "_ZN3CLSIiEEvNS_T_Ev",
 
     "_ZN1fIiEEvNTUt_E",
     "_ZNDTUt_Ev",
 
+    "_Z1fIXfLpt1x1yEEvv",
+    "_Z1fIXfLdt1x1yEEvv",
+
     "_ZN1fIXawLi0EEEEvv",
 
     "_ZNWUt_3FOOEv",
     "_ZWDC3FOOEv",
     "_ZGI3Foo",
     "_ZGIW3Foov",
     "W1x",
 };

llvm/include/llvm/Demangle/ItaniumDemangle.h

case 'l':
     IsLeftFold = true;
     break;
   case 'r':
     break;
   }
   ++First;
 
   const auto *Op = parseOperatorEncoding();
-  if (!Op || Op->getKind() != OperatorInfo::Binary)
+  if (!Op)
+    return nullptr;
+  if (!(Op->getKind() == OperatorInfo::Binary
+        || (Op->getKind() == OperatorInfo::Member
+            && Op->getName().back() == '*')))
     return nullptr;
 
   Node *Pack = getDerived().parseExpr();
   if (Pack == nullptr)
     return nullptr;
 
   Node *Init = nullptr;
   if (HasInitializer) {