Panics with "invalid offset" errors ( code: -32603) on "Go to definition" calls

rust-analyzer version: 0.3.2896

rustc version: rustc 1.95.0 (59807616e 2026-04-14)

editor: both VSCode and Zed

OS / Distro: Ubuntu 24.04 (WSL2) and Ubuntu 25.10

repository link: libpnet

Hi, I encountered an rust-analyzer panic when trying to go to any pnet::packet::*::*Packet packet abstraction struct implementation. Example:

// ...
let ethernet_frame = EthernetPacket::new(&packet).unwrap();
if ethernet_frame.get_ethertype() == EtherTypes::Ipv4 { ... }

when I try to peek the get_ethertype definition I get the following error:

thread 'Worker1' (13429) panicked at /github/home/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/line-index-0.1.2/src/lib.rs:111:35:
invalid offset
stack backtrace:
   0: __rustc::rust_begin_unwind
   1: core::panicking::panic_fmt
   2: core::option::expect_failed
   3: line_index::LineIndex::line_col
   4: rust_analyzer::lsp::to_proto::position
   5: rust_analyzer::lsp::to_proto::location_info
   6: rust_analyzer::lsp::to_proto::location_link
   7: <core::iter::adapters::map::Map<I,F> as core::iter::traits::iterator::Iterator>::try_fold
   8: <core::iter::adapters::GenericShunt<I,R> as core::iter::traits::iterator::Iterator>::next
   9: <alloc::vec::Vec<T> as alloc::vec::spec_from_iter::SpecFromIter<T,I>>::from_iter
  10: core::iter::adapters::try_process
  11: rust_analyzer::lsp::to_proto::goto_definition_response
  12: rust_analyzer::handlers::request::handle_goto_definition
  13: core::ops::function::FnOnce::call_once{{vtable.shim}}
  14: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
additional context:
   0: 
version: 0.3.2896-standalone
request: textDocument/definition GotoDefinitionParams {
    text_document_position_params: TextDocumentPositionParams {
        text_document: TextDocumentIdentifier {
            uri: Url {
                scheme: "file",
                cannot_be_a_base: false,
                username: "",
                password: None,
                host: None,
                port: None,
                path: ".../src/main.rs",
                query: None,
                fragment: None,
            },
        },
        position: Position {
            line: 105,
            character: 26,
        },
    },
    work_done_progress_params: WorkDoneProgressParams {
        work_done_token: None,
    },
    partial_result_params: PartialResultParams {
        partial_result_token: None,
    },
}

[Error - 6:47:32 PM] Request textDocument/definition failed.
  Message: request handler panicked: invalid offset
  Code: -32603

Seems like the custom derive(Packet) messes with rust-analyzer lsp

Reproduce the panic with libpnet by using Go to definition on a Packet method such as get_ethertype. Start with the stack frames in line-index-0.1.2/src/lib.rs and rust_analyzer::lsp::to_proto::position/location_link, then trace the textDocument/definition handler. Done means the request returns a valid definition location without an invalid-offset panic.