Error: Invalid Value Object

[ImkoMarijnissen]

OS: WSL 2 - Ubuntu 22.04
VSCode version: 1.93.1
CodeLLDB version: 1.10.1
Compiler: rustc
Debuggee: x86_64-linux-gnu

While debugging, I ran into the issue that I cannot see the values of vectors as it simply shows that <error: invalid value object> with the following error output message:

Verbose log

[DEBUG codelldb::dap_codec] --> {"command":"evaluate","arguments":{"expression":"boolean","frameId":1001,"context":"watch"},"type":"request","seq":26}
ERROR(Python) 13:47:14 codelldb: Traceback (most recent call last):
  File "/home/user/.vscode-server/extensions/vadimcn.vscode-lldb-1.10.0/adapter/scripts/codelldb/codelldb.py", line 175, in evaluate
    value = evaluate_in_context(pycode, is_simple_expr, context)
  File "/home/user/.vscode-server/extensions/vadimcn.vscode-lldb-1.10.0/adapter/scripts/codelldb/codelldb.py", line 320, in evaluate_in_context
    return eval(code, eval_globals, eval_locals)
  File "", line 1, in 
  File "/home/user/.vscode-server/extensions/vadimcn.vscode-lldb-1.10.0/adapter/scripts/codelldb/codelldb.py", line 309, in 
    eval_globals['__eval'] = lambda expr: nat_eval(frame, expr)
  File "/home/user/.vscode-server/extensions/vadimcn.vscode-lldb-1.10.0/adapter/scripts/codelldb/codelldb.py", line 300, in nat_eval
    raise Exception(err.GetCString())
Exception: error: could not find item

[elenakrittik]

Same issue for me!

[joshuataylor]

Also seeing this on RustRover, seems rust-lang/rust#126793 changed lldb_providers.py , I'll see if I can submit an issue..

[liukaizheng]

Because Rust have changed the implementation of Vec by using RawVec, which is essentially an u8 array, not a T array. Codelldb cannot't currently infer the type T by it's customized rust formmater. It still doesn't work even though I use the formatter provided by lldb_providers.py

class StdVecSyntheticProvider:
    def __init__(self, valobj, dict):
        self.valobj = valobj
        self.update()

    def num_children(self):
        return self.length

    def get_child_index(self, name):
        index = name.lstrip('[').rstrip(']')
        if index.isdigit():
            return int(index)
        else:
            return -1

    def get_child_at_index(self, index):
        start = self.data_ptr.GetValueAsUnsigned()
        address = start + index * self.element_type_size
        element = self.data_ptr.CreateValueFromAddress("[%s]" % index, address, self.element_type)
        return element

    def update(self):
        self.length = self.valobj.GetChildMemberWithName("len").GetValueAsUnsigned()
        self.buf = self.valobj.GetChildMemberWithName("buf").GetChildMemberWithName("inner")

        self.data_ptr = unwrap_unique_or_non_null(self.buf.GetChildMemberWithName("ptr"))

        self.element_type = self.valobj.GetType().GetTemplateArgumentType(0)
        self.element_type_size = self.element_type.GetByteSize()

    def has_children(self):
        return True

Finally I realized the reason for my failure was because the lldb with version 17.x provided by codelldb cannot infer the element_type:

self.element_type = self.valobj.GetType().GetTemplateArgumentType(0)

I guess It's can be solved by bumping lldb version to 18.x. I can't do it by myself because I don't know how to adapt this in codelldb. Oops, codelldb hasn't been updated in a long time

Also seeing this on RustRover, seems rust-lang/rust#126793 changed lldb_providers.py , I'll see if I can submit an issue..

[joshuataylor]

codelldb doesn't need to be updated often if it's working (lldb doesn't really update), apart from major updates like these :-)

[Shelim]

Any progress on this (or workarounds)? :)

[Shelim]

Workaround: when compiling specify +nightly-2024-08-01 instead of +nightly

[vadimcn]

As of v1.11, CodeLLDB will just use formatters shipped with rustc.