feat(scaffold): honor per-target core-dependency overrides in the scripting bindings (#164)

* feat(scaffold): target_dep_overrides for the scripting backends

Extend target_dep_overrides (previously ffi/jni/dart/swift only) to the
pyo3/napi/magnus/php/rustler backends, mirroring the FFI backend: when
overrides are set, the core dependency moves out of [dependencies] into a
cfg(not(...)) default block plus one [target.'cfg(<cfg>)'.dependencies] block
per override.

- shared render_core_dep_with_overrides helper in scaffold/mod.rs
- target_dep_overrides config field on Python/Node/Ruby/Php/Elixir (+ schema)
- wired all five scaffolds
- unit tests for the renderer + an all-five-backends integration test

Fixes #163.

* fix(tests): add target_dep_overrides to integration-test config literals

The new field was added to the src/scaffold/tests literals but the
integration tests under tests/ also construct PythonConfig/NodeConfig
as full struct literals; --all-targets compilation failed with E0063.
cargo check --all-targets, clippy (CI flags), and both affected test
binaries are green.

Author: tobocop2

schemas/alef.schema.json

@@ -2215,6 +2215,14 @@
             "string",
             "null"
           ]
+        },
+        "target_dep_overrides": {
+          "default": [],
+          "description": "Per-target overrides for the core-crate dependency emitted into the\ngenerated `Cargo.toml`. See [`super::FfiConfig::target_dep_overrides`].",
+          "items": {
+            "$ref": "#/$defs/FfiTargetDepOverride"
+          },
+          "type": "array"
         }
       },
       "type": "object"
@@ -3793,6 +3801,14 @@
             "null"
           ]
         },
+        "target_dep_overrides": {
+          "default": [],
+          "description": "Per-target overrides for the core-crate dependency emitted into the\ngenerated `Cargo.toml`. See [`super::FfiConfig::target_dep_overrides`].",
+          "items": {
+            "$ref": "#/$defs/FfiTargetDepOverride"
+          },
+          "type": "array"
+        },
         "tokio_util_features": {
           "default": null,
           "description": "Features for the auto-emitted `tokio-util` dependency that backs napi trait-bridge\ncancellation tokens. Defaults to `[\"rt\"]` because `tokio_util::sync::CancellationToken`\nis gated behind the `rt` feature in tokio-util 0.7+. Override when a consumer needs\nadditional tokio-util features (e.g. `[\"rt\", \"codec\"]`).",
@@ -4328,6 +4344,14 @@
           ],
           "default": null,
           "description": "Output directory for generated PHP facade / stubs (e.g., `packages/php/src/`)."
+        },
+        "target_dep_overrides": {
+          "default": [],
+          "description": "Per-target overrides for the core-crate dependency emitted into the\ngenerated `Cargo.toml`. See [`super::FfiConfig::target_dep_overrides`].",
+          "items": {
+            "$ref": "#/$defs/FfiTargetDepOverride"
+          },
+          "type": "array"
         }
       },
       "type": "object"
@@ -4684,6 +4708,14 @@
               "type": "null"
             }
           ]
+        },
+        "target_dep_overrides": {
+          "default": [],
+          "description": "Per-target overrides for the core-crate dependency emitted into the\ngenerated `Cargo.toml`. Mirrors [`super::FfiConfig::target_dep_overrides`]:\nwhen non-empty, the core dependency is wrapped in\n`[target.'cfg(not(<any-cfg>))'.dependencies]` plus one\n`[target.'cfg(<cfg>)'.dependencies]` block per override, so a specific\ntarget can swap the core crate's feature set.",
+          "items": {
+            "$ref": "#/$defs/FfiTargetDepOverride"
+          },
+          "type": "array"
         }
       },
       "type": "object"
@@ -5652,6 +5684,14 @@
               "type": "null"
             }
           ]
+        },
+        "target_dep_overrides": {
+          "default": [],
+          "description": "Per-target overrides for the core-crate dependency emitted into the\ngenerated `Cargo.toml`. See [`super::FfiConfig::target_dep_overrides`].",
+          "items": {
+            "$ref": "#/$defs/FfiTargetDepOverride"
+          },
+          "type": "array"
         }
       },
       "type": "object"

src/core/config/languages/elixir.rs

@@ -3,6 +3,8 @@ use serde::{Deserialize, Serialize};
 use std::collections::HashMap;
 use std::path::PathBuf;
 
+use super::FfiTargetDepOverride;
+
 #[derive(Debug, Clone, Serialize, Deserialize, JsonSchema)]
 pub struct ElixirConfig {
     pub app_name: Option<String>,
@@ -55,4 +57,8 @@ pub struct ElixirConfig {
     /// `aarch64-apple-darwin, aarch64-unknown-linux-gnu, x86_64-unknown-linux-gnu, x86_64-pc-windows-gnu`.
     #[serde(default)]
     pub nif_targets: Vec<String>,
+    /// Per-target overrides for the core-crate dependency emitted into the
+    /// generated `Cargo.toml`. See [`super::FfiConfig::target_dep_overrides`].
+    #[serde(default)]
+    pub target_dep_overrides: Vec<FfiTargetDepOverride>,
 }

src/core/config/languages/node.rs

@@ -3,6 +3,8 @@ use serde::{Deserialize, Serialize};
 use std::collections::HashMap;
 use std::path::PathBuf;
 
+use super::FfiTargetDepOverride;
+
 /// Configuration for a single capsule type entry in `NodeConfig::capsule_types`.
 ///
 /// When set, the named Rust type is NOT emitted as a `#[napi]` opaque wrapper.
@@ -125,4 +127,8 @@ pub struct NodeConfig {
     /// Extra paths to append to default lint commands (format, check, typecheck).
     #[serde(default)]
     pub extra_lint_paths: Vec<String>,
+    /// Per-target overrides for the core-crate dependency emitted into the
+    /// generated `Cargo.toml`. See [`super::FfiConfig::target_dep_overrides`].
+    #[serde(default)]
+    pub target_dep_overrides: Vec<FfiTargetDepOverride>,
 }

src/core/config/languages/php.rs

@@ -3,7 +3,7 @@ use serde::{Deserialize, Serialize};
 use std::collections::HashMap;
 use std::path::PathBuf;
 
-use super::StubsConfig;
+use super::{FfiTargetDepOverride, StubsConfig};
 
 #[derive(Debug, Clone, Serialize, Deserialize, JsonSchema)]
 pub struct PhpConfig {
@@ -62,4 +62,8 @@ pub struct PhpConfig {
     /// Extra paths to append to default lint commands (format, check, typecheck).
     #[serde(default)]
     pub extra_lint_paths: Vec<String>,
+    /// Per-target overrides for the core-crate dependency emitted into the
+    /// generated `Cargo.toml`. See [`super::FfiConfig::target_dep_overrides`].
+    #[serde(default)]
+    pub target_dep_overrides: Vec<FfiTargetDepOverride>,
 }

src/core/config/languages/python.rs

@@ -3,7 +3,7 @@ use serde::{Deserialize, Serialize};
 use std::collections::HashMap;
 use std::path::PathBuf;
 
-use super::StubsConfig;
+use super::{FfiTargetDepOverride, StubsConfig};
 
 /// Configuration for a single capsule type entry in `PythonConfig::capsule_types`.
 ///
@@ -143,4 +143,12 @@ pub struct PythonConfig {
     /// `ExtractionResult` instead of `_rust.ExtractionResult`.
     #[serde(default)]
     pub reexported_types: Vec<String>,
+    /// Per-target overrides for the core-crate dependency emitted into the
+    /// generated `Cargo.toml`. Mirrors [`super::FfiConfig::target_dep_overrides`]:
+    /// when non-empty, the core dependency is wrapped in
+    /// `[target.'cfg(not(<any-cfg>))'.dependencies]` plus one
+    /// `[target.'cfg(<cfg>)'.dependencies]` block per override, so a specific
+    /// target can swap the core crate's feature set.
+    #[serde(default)]
+    pub target_dep_overrides: Vec<FfiTargetDepOverride>,
 }

src/core/config/languages/ruby.rs

@@ -3,7 +3,7 @@ use serde::{Deserialize, Serialize};
 use std::collections::HashMap;
 use std::path::PathBuf;
 
-use super::StubsConfig;
+use super::{FfiTargetDepOverride, StubsConfig};
 
 #[derive(Debug, Clone, Serialize, Deserialize, JsonSchema)]
 pub struct RubyConfig {
@@ -41,4 +41,8 @@ pub struct RubyConfig {
     /// Extra paths to append to default lint commands (format, check, typecheck).
     #[serde(default)]
     pub extra_lint_paths: Vec<String>,
+    /// Per-target overrides for the core-crate dependency emitted into the
+    /// generated `Cargo.toml`. See [`super::FfiConfig::target_dep_overrides`].
+    #[serde(default)]
+    pub target_dep_overrides: Vec<FfiTargetDepOverride>,
 }

src/scaffold/languages/elixir.rs

@@ -66,13 +66,24 @@ pub(crate) fn scaffold_elixir_cargo(
     // Collect all [dependencies] entries then sort alphabetically so the emitted
     // Cargo.toml is cargo-sort canonical without a post-processing step.
     let features_str = core_dep_features(config, Language::Elixir);
+    let core_overrides = config
+        .elixir
+        .as_ref()
+        .map(|c| c.target_dep_overrides.as_slice())
+        .unwrap_or(&[]);
+    let (core_dep_line, core_target_blocks) = crate::scaffold::render_core_dep_with_overrides(
+        &config.name,
+        &format!("../../../../crates/{core_crate_dir}"),
+        &features_str,
+        version,
+        core_overrides,
+    );
+    let core_target_blocks_section = if core_target_blocks.is_empty() {
+        String::new()
+    } else {
+        format!("\n{core_target_blocks}")
+    };
     let mut dep_lines: Vec<String> = vec![
-        crate::scaffold::render_core_dep(
-            &config.name,
-            &format!("../../../../crates/{core_crate_dir}"),
-            &features_str,
-            version,
-        ),
         format!("rustler = \"{}\"", tv::cargo::RUSTLER),
         "serde = { version = \"1\", features = [\"derive\"] }".to_owned(),
         "serde_json = \"1\"".to_owned(),
@@ -108,6 +119,9 @@ pub(crate) fn scaffold_elixir_cargo(
     dep_lines.push("alloc-no-stdlib = \"=2.0.4\"".to_owned());
     dep_lines.push("alloc-stdlib = \"=0.2.2\"".to_owned());
     dep_lines.push("brotli-decompressor = \"=5.0.1\"".to_owned());
+    if !core_dep_line.is_empty() {
+        dep_lines.push(core_dep_line);
+    }
     dep_lines.sort();
     let deps_section = dep_lines.join("\n");
 
@@ -232,14 +246,15 @@ name = "{nif_name}"
 crate-type = ["cdylib"]
 
 {features_table}[dependencies]
-{deps_section}{check_cfg_block}"#,
+{deps_section}{core_target_blocks_section}{check_cfg_block}"#,
         pkg_header = pkg_header,
         machete_section = machete_section,
         nif_name = nif_name,
         lib_path_line = lib_path_line,
         features_table = features_table,
         check_cfg_block = check_cfg_block,
         deps_section = deps_section,
+        core_target_blocks_section = core_target_blocks_section,
     );
 
     Ok(vec![GeneratedFile {

src/scaffold/languages/node.rs

@@ -221,12 +221,23 @@ pub(crate) fn scaffold_node_cargo(
     // Build [dependencies] block alphabetically sorted to match cargo-sort.
     // Order: async-trait?, futures-util?, <core-crate>, napi,
     // napi-derive, serde, serde_json, + any extra deps.
-    let core_dep = crate::scaffold::render_core_dep(
+    let core_overrides = config
+        .node
+        .as_ref()
+        .map(|c| c.target_dep_overrides.as_slice())
+        .unwrap_or(&[]);
+    let (core_dep, core_target_blocks) = crate::scaffold::render_core_dep_with_overrides(
         &config.name,
         &format!("../{core_crate_dir}"),
         &core_dep_features(config, Language::Node),
         version,
+        core_overrides,
     );
+    let core_target_blocks_section = if core_target_blocks.is_empty() {
+        String::new()
+    } else {
+        format!("{core_target_blocks}\n")
+    };
     let mut dep_entries: Vec<String> = vec![
         format!(
             "napi = {{ version = \"{napi}\", features = [{napi_features_str}] }}",
@@ -288,12 +299,13 @@ crate-type = ["cdylib"]
 {features_table}[dependencies]
 {dep_block}
 
-[build-dependencies]
+{core_target_blocks_section}[build-dependencies]
 napi-build = "{napi_build}"
 
 "#,
         pkg_header = pkg_header,
         dep_block = dep_block,
+        core_target_blocks_section = core_target_blocks_section,
         features_table = features_table,
         machete_ignored_str = machete_ignored_str,
         napi_build = tv::cargo::NAPI_BUILD,

src/scaffold/languages/php.rs

@@ -75,12 +75,23 @@ pub(crate) fn scaffold_php_cargo(api: &ApiSurface, config: &ResolvedCrateConfig)
     // Build [dependencies] block alphabetically sorted to match cargo-sort.
     // Order: async-trait?, ext-php-rs, futures-util?, <core-crate>,
     // serde, serde_json, tokio.
-    let core_dep_php = crate::scaffold::render_core_dep(
+    let core_overrides = config
+        .php
+        .as_ref()
+        .map(|c| c.target_dep_overrides.as_slice())
+        .unwrap_or(&[]);
+    let (core_dep_php, core_target_blocks) = crate::scaffold::render_core_dep_with_overrides(
         &config.name,
         &format!("../{core_crate_dir}"),
         &core_dep_features(config, Language::Php),
         version,
+        core_overrides,
     );
+    let core_target_blocks_section = if core_target_blocks.is_empty() {
+        String::new()
+    } else {
+        format!("\n{core_target_blocks}")
+    };
     let mut dep_entries: Vec<String> = vec![
         format!("ext-php-rs = \"{}\"", tv::cargo::EXT_PHP_RS),
         "serde = { version = \"1\", features = [\"derive\"] }".to_string(),
@@ -139,10 +150,11 @@ extension-module = []
 {cfg_forwarding}
 [dependencies]
 {dep_block}
-
+{core_target_blocks_section}
 "#,
         pkg_header = pkg_header,
         dep_block = dep_block,
+        core_target_blocks_section = core_target_blocks_section,
         machete_ignored_str = machete_ignored_str,
         cfg_forwarding = cfg_forwarding,
     );

src/scaffold/languages/python.rs

@@ -157,12 +157,25 @@ pub(crate) fn scaffold_python_cargo(
         .collect::<Vec<_>>()
         .join(", ");
     // Build [dependencies] block alphabetically sorted to match cargo-sort.
-    let core_dep_py = crate::scaffold::render_core_dep(
+    // When target_dep_overrides are configured, the core dep moves into
+    // `[target.'cfg(...)'.dependencies]` blocks (core_dep_py is then empty).
+    let core_overrides = config
+        .python
+        .as_ref()
+        .map(|p| p.target_dep_overrides.as_slice())
+        .unwrap_or(&[]);
+    let (core_dep_py, core_target_blocks) = crate::scaffold::render_core_dep_with_overrides(
         &config.name,
         &format!("../{core_crate_dir}"),
         &core_dep_features(config, Language::Python),
         version,
+        core_overrides,
     );
+    let core_target_blocks_section = if core_target_blocks.is_empty() {
+        String::new()
+    } else {
+        format!("\n{core_target_blocks}")
+    };
     let mut dep_entries: Vec<String> = vec![
         format!("pyo3 = {{ version = \"{}\" }}", tv::cargo::PYO3),
         format!(
@@ -207,11 +220,12 @@ extension-module = ["pyo3/extension-module", "pyo3/abi3-py310"]
 
 [dependencies]
 {dep_block}
-
+{core_target_blocks_section}
 "#,
         pkg_header = pkg_header,
         module_name = module_name,
         dep_block = dep_block,
+        core_target_blocks_section = core_target_blocks_section,
         machete_ignored_str = machete_ignored_str,
     );