clangd sometimes crashes parsing a spliced expand statement

[fzuuzf]

The crash seams to only happen, if the spliced expand statement is located in an included file.

To Reproduce
See https://github.com/fzuuzf/crash_clang-p2996-clangd

I also ran clangd with this applied:

--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -7585,6 +7585,7 @@ ASTRecordReader::readTemplateArgumentLocInfo(TemplateArgument::ArgKind Kind) {
   case TemplateArgument::NullPtr:
   case TemplateArgument::StructuralValue:
   case TemplateArgument::Pack:
+  case TemplateArgument::SpliceSpecifier:
     // FIXME: Is this right?
     return TemplateArgumentLocInfo();
   }

While I don't know if it is correct, it helps avoid another crash. It doesn't help the $title issue.

[Yaraslaut]

I suppose that the issue is in wrong usage of expand statement,
here is a godbolt example https://godbolt.org/z/o54vrdvdr of what is happening

Edit: and here is example on godbolt with cmake and header file from the repo
https://godbolt.org/z/cfhbcT5h5

[fzuuzf]

I think the repo's code is not wrong, the expand statement is just unused.

https://godbolt.org/z/bqGa1xaMv
has your example except the expand statement is used.
It lets Clangd here crash just the same.

EDIT: https://github.com/fzuuzf/crash_clang-p2996-clangd now shows the build setups, I used.

[fzuuzf]

The culprit likely is:
clang::Stmt::CXXSpliceExprBitfields::HasTemplateKWAndArgsInfo
not being default initialized.

By the way, what does the KW in HasTemplateKWAndArgsInfo stand for?

EDIT: See pull request #106