tauri-apps/tauri · error

parsed syn::Path has no segment

Error message

parsed syn::Path has no segment

What it means

path_to_command in tauri-macros unwraps the last segment of a parsed syn::Path and panics if the path is empty. The doc comment states this panic is intentional: the helper's contract requires a non-empty path, and callers always pass paths derived from valid command references.

Solutions

1. Update tauri-macros to the latest version
2. Verify command reference paths in attributes are fully qualified and non-empty
3. Reduce to a minimal repro and report upstream if the panic persists

Example fix

// before
// empty path passed through generated code
let path = syn::parse_str::<syn::Path>("#").unwrap();
path_to_command(&mut path);
// after
let path = syn::parse_str::<syn::Path>("my_crate::command_name").unwrap();
path_to_command(&mut path);

fn path_has_segments(p: &syn::Path) -> bool { !p.segments.is_empty() }

// compile-time panic from proc macro; mitigate via version pinning
// Cargo.toml
tauri = "= <known-good-version>"  // upgrade to latest before investigating further

When it happens

Trigger: Invoking the command macro machinery (wrapper/handler generation) with a syn::Path containing no segments — an internal contract violation from malformed macro input.

Common situations: Only via proc-macro bugs or generated code producing empty paths; end users see it as a tauri-macros compile panic, usually fixed by upgrading.

Understand the failure class

Background: "This is a bug, please report it": internal invariant violations, unreachable panics, and SNH errors explained — this error's family across 47 libraries.

Related errors

• path has at least one segment
• expected "camelCase" or "snake_case"
• expected string literal for rename
• only named, wildcard, struct, and tuple struct arguments…
• unable to use self as a command function parameter

AI-assisted analysis of tauri-apps/tauri@460ec35447 (2026-09-18). Data as JSON: /api/errors/4bfa2079fede7f3c. Report an issue: GitHub.

Appendix: source

Thrown at crates/tauri-macros/src/command/mod.rs:23

use proc_macro2::Ident;
use syn::{Path, PathSegment};

pub use self::{handler::Handler, wrapper::wrapper};

mod handler;
mod wrapper;

/// The autogenerated wrapper ident.
fn format_command_wrapper(function: &Ident) -> Ident {
  quote::format_ident!("__cmd__{}", function)
}

/// This function will panic if the passed [`syn::Path`] does not have any segments.
fn path_to_command(path: &mut Path) -> &mut PathSegment {
  path
    .segments
    .last_mut()
    .expect("parsed syn::Path has no segment")
}

View on GitHub (pinned to 460ec35447)