Ref: llvm/llvm-project@e42b799

Ref: llvm/llvm-project@dd647e3

Ref: llvm/llvm-project@5845688

Ref: llvm/llvm-project@458328a

fix headers - llvm/llvm-project@6194668

TemplateArgument can return a QualType that may contain
unqualified parts.

Before (incorrect):
  __gnu_cxx::__common_pool_policy<__pool, true>

After (correct):
  __gnu_cxx::__common_pool_policy<__gnu_cxx::__pool, true>

LLVM 20 produce `RecoveryExpr` for dependent errors where LLVM 18 returned
`ExprError`.

In our type/name lookup path, this can leave a <recovery-expr> node and
later codeGen asks the AST to constant-evaluate that initializer and we hit
this assertion:

`VarDecl::evaluateValueImpl: !Init->isValueDependent()`.

Avoid cases like: avoid `class__attribute__` with LLVM20

Fixes the failure on alma9:
`gtest-tree-dataframe-dataframe-snapshot-emptyoutput`

…thods

Skip dumping TopLevelStmt if they are invalid.

The change llvm/llvm-project@4b70d17bcf caused an invalid
`TopLevelStatement` to be added to the AST, which can trigger
assertions when dumping.

Also temporarily failing disable `testHashRecursiveRemove` test on Windows

template_arguments() has the types, but getTemplateArgs() has the
pack argument, so their counts may be different. Add test for failing
CMS build with LLVM 20.

Co-authored-by: Devajith Valaparambil Sreeramaswamy <[email protected]>