node:process: populate process.config variables and target_defaults

[andrewtdiz]

Summary

Node exposes process.config as a populated build-time configuration object with variables and target_defaults fields. Perry origin/main currently synthesizes only the broad object shape with empty sub-objects, which is enough for typeof process.config === 'object' but not enough for packages that inspect Node build variables.

Node docs: https://nodejs.org/api/process.html#processconfig

Node behavior

Local Node probe with node v25.9.0:

config type object object object
variable keys sample debug_node,host_arch,icu_gyp_path,icu_small,icu_ver_major,node_builtin_shareable_builtins,node_byteorder,node_cctest_sources,node_debug_lib,node_enable_d8,node_enable_v8_vtunejit,node_enable_v8windbg,node_fipsinstall,node_install_corepack,node_install_npm,node_library_files,node_module_version,node_no_browser_globals,node_prefix,node_release_urlbase
target keys cflags,conditions,configurations,default_configuration,defines,include_dirs,libraries
node_shared_openssl true
target_arch arm64

Probe script:

console.log('config type', typeof process.config, typeof process.config.variables, typeof process.config.target_defaults);
console.log(
  'variable keys sample',
  Object.keys(process.config.variables).filter(k => /arch|openssl|node|v8|uv|icu/.test(k)).sort().slice(0, 20).join(','),
);
console.log('target keys', Object.keys(process.config.target_defaults).sort().join(','));
console.log('node_shared_openssl', process.config.variables.node_shared_openssl);
console.log('target_arch', process.config.variables.target_arch);

Perry evidence

Source review against origin/main:

• crates/perry-hir/src/lower/expr_member.rs handles process.config by returning:

Expr::Object(vec![
    ("variables".to_string(), Expr::Object(Vec::new())),
    ("target_defaults".to_string(), Expr::Object(Vec::new())),
])

• The nearby source comment says this intentionally returns the shape with empty sub-objects for feature detection.
• docs/runtime-parity.md marks process.config as covered.
• test-files/test_parity_process.ts only checks typeof process.config and skips Object.keys(process.config) because the older undefined shape crashed.
• test-parity/node-suite/process/config/config.ts expects variables and target_defaults objects but does not assert meaningful key/value coverage.

Duplicate check

Searched existing issues and PRs for:

• process.config variables target_defaults

The only match was merged PR #1484 / closed #1379, which implemented the broad object shape after process.config was undefined. This issue is a follow-up for populated Node-compatible metadata values, not for the existence of process.config itself.

Expected compatibility

• process.config.variables exposes representative Node-compatible build variables used by ecosystem feature detection, such as target_arch, host_arch, node_module_version, node_shared_openssl, and relevant v8 / uv / icu flags.
• process.config.target_defaults exposes the standard object shape with keys such as cflags, default_configuration, defines, include_dirs, and libraries.
• Values can be Perry-specific where Node internals do not apply, but missing keys should be deliberate and documented.
• Parity tests should assert representative keys and value types, not only typeof.

Scope / non-goals

• This does not require pretending Perry is a full Node binary or matching every host-specific Node build flag byte-for-byte.
• It should provide stable, truthful, package-compatible metadata for common feature detection and native-addon tooling checks.

[andrewtdiz]

I’m taking this with #3686 in a coherent node:process metadata/coherence PR cut.

Intended scope: populate representative, stable process.config.variables and process.config.target_defaults metadata used by package feature detection, and make that same config surface visible through direct global reads, node:process default/namespace imports, and captured/dynamic property reads.

Non-goals for this cut: pretending Perry is a byte-for-byte Node build or implementing unrelated process lifecycle/report/permission APIs.

[andrewtdiz]

Implemented in draft PR #4075: #4075

This populates process.config with Node-shaped variables and target_defaults containers as part of the broader node:process metadata coherence fix.