windmill-labs/windmill · error

Error setting R as language: {e}

Error message

Error setting R as language: {e}

What it means

parse_r_sig_meta in windmill-parser-r initializes a tree-sitter parser for R via parser.set_language(tree_sitter_r::LANGUAGE). Failure here means the tree-sitter runtime could not load/accept the R grammar (version or ABI incompatibility between tree-sitter and the language crate), and the parser throws 'Error setting R as language: ...'.

Source

Thrown at backend/parsers/windmill-parser-r/src/lib.rs:19

#![cfg_attr(target_arch = "wasm32", feature(c_variadic))]

#[cfg(target_arch = "wasm32")]
pub mod wasm_libc;

use anyhow::anyhow;
use serde_json::Value;
use tree_sitter::Node;
use tree_sitter::Range;
use windmill_parser::json_to_typ;
use windmill_parser::Arg;
use windmill_parser::MainArgSignature;

pub fn parse_r_sig_meta(code: &str) -> anyhow::Result<MainArgSignature> {
    let mut parser = tree_sitter::Parser::new();
    let language = tree_sitter_r::LANGUAGE;
    parser
        .set_language(&language.into())
        .map_err(|e| anyhow!("Error setting R as language: {e}"))?;

    let tree = parser
        .parse(code, None)
        .ok_or(anyhow!("Failed to parse code"))?;
    let root_node = tree.root_node();

    let args = find_main_signature(root_node, code)?;
    let main_sig = MainArgSignature {
        star_args: false,
        star_kwargs: false,
        args: args.unwrap_or_default(),
        has_preprocessor: None,
        auto_kind: None,
        ..Default::default()
    };

    Ok(main_sig)
}

View on GitHub (pinned to e474e8803c)

Solutions

1. Check Cargo.lock for tree-sitter and tree-sitter-r version compatibility; align tree-sitter-r to the tree-sitter core version in use.
2. Run 'cargo update -p tree-sitter-r' (or pin both) and rebuild the backend.
3. Rebuild from a clean target/ to rule out stale FFI artifacts between grammar versions.
4. If it persists, file an issue with the backend build log — the user's R code content is irrelevant here.

Example fix

# before (lockfile)
tree-sitter = "0.20"
tree-sitter-r = "0.24"

# after
cargo update -p tree-sitter-r  # aligned with the tree-sitter core version

match parse_r_signature(code) {
    Err(e) if e.to_string().contains("Error setting R as language") => {
        // environment/build issue, not user code: surface as infra error
        Err(anyhow!("R grammar failed to load (deployment/build issue): {e}"))
    }
    other => other,
}

When it happens

Trigger: Calling parse_r_sig_meta (via parse_r_signature) when set_language rejects the grammar — typically a tree-sitter core / tree-sitter-r version mismatch in the build, or an unsafe/ABI issue in the compiled grammar, not anything in the user's R code.

Common situations: Building windmill with mismatched tree-sitter crate versions in the lockfile, a toolchain/FFI issue on the target platform, or an upgrade of tree-sitter without regenerating/upgrading tree-sitter-r.

Related errors

• Failed to parse code
• snprintf is not supported
• oh no
• Aborted from C
• clock is not supported

AI-assisted analysis of windmill-labs/windmill@e474e8803c (2026-09-03). Data as JSON: /api/errors/91bee2dd0fa8239a. Report an issue: GitHub.