lldb fails to display a local var when its type defined in a lexical block

[chbessonova]

Consider the following example (compiled by gcc because clang doesn't emit correct scope for types if they defined in a lexical block, support for clang D113743):

  * thread #1, name = 'a.out', stop reason = step over
      frame #0: 0x000000000040111d a.out`foo(a=1) at test_lldb.cpp:5:12
     1          int foo(int a) {
     2   	  {
     3   	    typedef int Int;
     4   	    Int local = a;
  -> 5   	    return local;
     6   	  }
     7   	}
     8
  (lldb) p local
  error: expression failed to parse:
  error: <lldb wrapper prefix>:45:31: no member named 'local' in namespace '$__lldb_local_vars'
      using $__lldb_local_vars::local;
            ~~~~~~~~~~~~~~~~~~~~^
  error: <user expression 0>:1:1: use of undeclared identifier 'local'
  local
^

lldb failed to find 'local' variable typed with a lexical block defined type (typedef Int).
The immediate cause of this issue is that clang failed to import this typedef:

lldb   (x86_64) a.out: DWARFASTParserClang::ParseTypeFromDWARF (die = 0x00000070, decl_ctx = 0x2509cb0 (die 0x00000055)) DW_TAG_typedef name = 'Int')
lldb   (x86_64) a.out: SymbolFileDWARF::ResolveTypeUID (die = 0x00000070) DW_TAG_typedef 'Int'
lldb   (x86_64) a.out: SymbolFileDWARF::ResolveTypeUID (die = 0x00000096) DW_TAG_base_type 'int'
lldb   Compiler diagnostic:

lldb   Couldn't import type: UnsupportedConstruct
lldb   Couldn't copy a variable's type into the parser's AST context

The importing wasn't succeed because clang wasn't able to import typedef's context, which is actually a BlockDecl (import for BlockDecl isn't implemented, but this is still a question to me why DW_TAG_lexical_block is associated with a BlockDecl).

I have a workaround for this issue (see D115277), but a proper fix is still needed.

[llvmbot]

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