BoundaryML/baml · critical

precompiled stdlib is missing package `{package}`

Error message

precompiled stdlib is missing package `{package}`

What it means

Panic from `ProjectDatabase::ensure_precompiled_stdlib`. A precompiled stdlib is all-or-nothing: the supplied `interfaces` map must contain an entry for every embedded stdlib package. When a package's name is missing from the map, the installer panics rather than silently leaving the stdlib incomplete.

Source

Thrown at baml_language/crates/baml_db/src/db.rs:428

        });
    }

    /// Install one `Stdlib` root per embedded builtin package served from its
    /// compiler-built interface (`borsh(PackageInterface)`, keyed by package
    /// name) instead of from source — the runtime compiler's shape, where the
    /// stdlib arrives precompiled and no builtin source is materialized. The
    /// dependency edges come from the embedded manifests exactly as for
    /// source roots.
    ///
    /// # Panics
    ///
    /// Panics if `interfaces` lacks a stdlib package: a precompiled stdlib is
    /// all-or-nothing.
    pub fn ensure_precompiled_stdlib(&mut self, interfaces: &BTreeMap<String, Vec<u8>>) {
        self.install_stdlib(|package| StdlibProvenance::Interface {
            bytes: interfaces
                .get(package)
                .unwrap_or_else(|| panic!("precompiled stdlib is missing package `{package}`"))
                .clone(),
        });
    }

    /// The one stdlib installer: create (or reuse) the roots of
    /// [`stdlib_layout`] in dependency order, each with its manifest-declared
    /// edges, and record the prelude every later root receives at creation.
    ///
    /// # Panics
    ///
    /// Panics if a non-`Stdlib` root already exists: the stdlib is installed
    /// first, so its roots are the lowest ids in the database and the root
    /// order the type algebra sorts by agrees with the table order emit
    /// iterates.
    fn install_stdlib(&mut self, provenance: impl Fn(&str) -> StdlibProvenance) {
        // The stdlib is installed before any other root, so the stdlib roots
        // are the lowest ids in the database: the root order the type algebra
        // sorts by (creation order) and the table order emit iterates agree

View on GitHub (pinned to bd85ce9dee)

Solutions

1. Build the interfaces map from the same embedded stdlib layout so every package is present.
2. Log which keys are missing versus the expected package names before calling.
3. Regenerate the full precompiled stdlib artifact set for the current compiler version.

Example fix

// before
db.ensure_precompiled_stdlib(&partial_map); // missing "core"
// after
let full: BTreeMap<String, Vec<u8>> = stdlib_layout().packages.iter()
    .map(|p| Ok((p.name.to_string(), get_interface(p.name)?)))
    .collect::<Result<_, _>>()?;
db.ensure_precompiled_stdlib(&full);

fn interfaces_complete(map: &BTreeMap<String, Vec<u8>>) -> Result<(), Vec<String>> {
    let missing: Vec<String> = stdlib_layout().packages.iter()
        .map(|p| p.name.to_string())
        .filter(|n| !map.contains_key(n))
        .collect();
    if missing.is_empty() { Ok(()) } else { Err(missing) }
}

// This is a panic, not a Result: validate the map beforehand and fail gracefully.
if let Err(missing) = interfaces_complete(&interfaces) {
    panic!("precompiled stdlib incomplete; missing: {missing:?}");
}
db.ensure_precompiled_stdlib(&interfaces);

When it happens

Trigger: Calling `ensure_precompiled_stdlib(&BTreeMap<String, Vec<u8>>)` whose key set does not cover all stdlib package names (checked inside the installer via `interfaces.get(package).unwrap_or_else(panic!)`).

Common situations: Partially populated interface maps produced by an artifact build that skipped a package; key/name mismatch between the embedded stdlib manifest and the map keys after a version bump.

Understand the failure class

Background: "not installed", "pip install", "required for": how missing-dependency errors surface across open-source libraries — this error's family across 34 libraries.

Related errors

• cannot install the stdlib source root for `{}`: {err}
• `{BAML_JSON_JSON}` is declared by the stdlib
• sys_op callee must resolve to a statically-known global func
• expected jump instruction at index {instruction_idx}
• exhaustive realized-leaf template classification

AI-assisted analysis of BoundaryML/baml@bd85ce9dee (2026-09-12). Data as JSON: /api/errors/4091b9433a7147f6. Report an issue: GitHub.