refactor!: replace build.rs with compile-time macro build steps

BREAKING CHANGE: Replace the `build`/`builds` feature system with
compile-time macro-driven generation. `gen_program!()` now automatically
invokes `build_comp!()` and `build_pathf!()` when the `comp`/`pathf`
features are enabled, eliminating the need for `build.rs` and
`[build-dependencies]` blocks.

This removes the `build` feature, the `mingling::build` module, and all
related build-time API functions. Completion scripts are now written to
`{target_directory}/mingling/` instead of `target/release/`. The
`mingling_cli` uses `build_comp!("mling")` for its custom binary name.

3 files changed, 16 insertions, 114 deletions

diff --git a/mingling/src/example_docs.rs b/mingling/src/example_docs.rs
index 2b1d21e..c9955b5 100644
--- a/mingling/src/example_docs.rs
+++ b/mingling/src/example_docs.rs
@@ -595,11 +595,13 @@ pub mod example_clap_binding {}
 ///  > Types are defined in a submodule (`sub`), and `gen_program!()` resolves
 ///  > them automatically via pathf without explicit `use` imports.
 ///  >
-///  > **Important**: `dispatch_tree` must be enabled in BOTH `[dependencies]`
-///  > AND `[build-dependencies]` so that pathf's builder can detect
-///  > `__internal_dispatcher_*` types needed by the dispatch tree.
+///  > **Important**: `dispatch_tree` must be enabled so that pathf's builder can
+///  > detect `__internal_dispatcher_*` types needed by the dispatch tree.
 ///  >
 ///  > Also requires `extras` for the implicit `dispatcher!("hello")` form.
+///  >
+///  > With the `pathf` feature, `gen_program!()` automatically invokes
+///  > `build_pathf!()` at compile time — no `build.rs` needed.
 ///
 ///  Run:
 ///  ```bash
@@ -625,19 +627,6 @@ pub mod example_clap_binding {}
 ///     "pathf",
 /// ] }
 ///
-/// [build-dependencies]
-/// mingling = { path = "../../mingling", features = [
-///     "builds",
-///
-///     # --------- IMPORTANT ---------
-///     # To use pathf under dispatch_tree
-///     #   **must** enable the `dispatch_tree`
-///     #   feature in build dependencies
-///     "dispatch_tree",
-///     "pathf",
-///     # --------- IMPORTANT ---------
-/// ] }
-///
 /// [workspace]
 /// ```
 ///
@@ -691,15 +680,6 @@ pub mod example_combine_pathf_dispatch_tree {}
 ///     "pathf",
 /// ]
 ///
-/// [build-dependencies.mingling]
-/// path = "../../mingling"
-/// features = [
-///     # Enable the `build` feature for build-time support
-///     "build",
-///     # `pathf` must also be enabled in build-dependencies
-///     "pathf",
-/// ]
-///
 /// [workspace]
 /// ```
 ///
@@ -811,30 +791,15 @@ pub mod example_command_macro {}
 ///  To make your completions work, you need to generate a completion script using Mingling's tools
 ///
 ///  1. Enable features
-///     You need to enable the `build` and `comp` features for `mingling` in `[build-dependencies]`
-///
-///  2. Write `build.rs`
-///     Write the following in `build.rs`
-///
-///  ```rust,ignore
-///  fn main() {
-///      build_scripts();
-///  }
-///
-///  /// Generate completion scripts
-///  fn build_scripts() {
-///      // `env!("CARGO_PKG_NAME")` equals the crate name, which matches the binary name.
-///      // If your binary name differs from the crate name, specify it explicitly.
-///      mingling::build::build_comp_scripts(
-///          // Your binary name:
-///          env!("CARGO_PKG_NAME"),
-///      )
-///      .unwrap();
-///  }
-///  ```
+///     Enable the `comp` feature for `mingling` in `[dependencies]`
+///
+///  2. Generate completion scripts
+///     When the `comp` feature is enabled, `gen_program!()` automatically invokes
+///     `build_comp!()` at compile time, which generates the completion scripts
+///     (named after `CARGO_PKG_NAME`) into `target/mingling/`.
 ///
 ///  3. Verify
-///     Build your project with `cargo build --release`. The completion scripts will be generated in `target/release/`
+///     Build your project with `cargo build`. The completion scripts will be generated in `target/mingling/`
 ///
 ///     Execute the script or have it be automatically sourced by your Shell
 ///
@@ -864,18 +829,6 @@ pub mod example_command_macro {}
 ///     "picker",
 /// ]
 ///
-/// [build-dependencies.mingling]
-/// path = "../../mingling"
-///
-/// features = [
-///     # Enable `comp` features
-///     "comp",
-///
-///     # If you want to build completion scripts,
-///     # enable `build` features
-///     "build",
-/// ]
-///
 /// [workspace]
 /// ```
 ///
@@ -2104,17 +2057,6 @@ pub mod example_panic_unwind {}
 ///     "pathf",
 /// ]
 ///
-/// [build-dependencies.mingling]
-/// path = "../../mingling"
-///
-/// features = [
-///     # Enable `pathf` features
-///     "pathf",
-///
-///     # Enable the `build` feature for build-time support
-///     "build",
-/// ]
-///
 /// [workspace]
 /// ```
 ///
diff --git a/mingling/src/features.rs b/mingling/src/features.rs
index 9445328..777c3fb 100644
--- a/mingling/src/features.rs
+++ b/mingling/src/features.rs
@@ -31,50 +31,6 @@ pub const MINGLING_ASYNC: bool = false;
 #[cfg(feature = "async")]
 #[allow(unused)]
 pub const MINGLING_ASYNC: bool = true;
-/// Whether the `build` feature is enabled
-/// Current: `disabled`
-#[cfg(not(feature = "build"))]
-#[allow(unused)]
-pub const MINGLING_BUILD: bool = false;
-
-/// Whether the `build` feature is enabled
-/// Current: `enabled`
-#[cfg(feature = "build")]
-#[allow(unused)]
-pub const MINGLING_BUILD: bool = true;
-/// Whether the `build_advanced` feature is enabled
-/// Current: `disabled`
-#[cfg(not(feature = "build_advanced"))]
-#[allow(unused)]
-pub const MINGLING_BUILD_ADVANCED: bool = false;
-
-/// Whether the `build_advanced` feature is enabled
-/// Current: `enabled`
-#[cfg(feature = "build_advanced")]
-#[allow(unused)]
-pub const MINGLING_BUILD_ADVANCED: bool = true;
-/// Whether the `build_full` feature is enabled
-/// Current: `disabled`
-#[cfg(not(feature = "build_full"))]
-#[allow(unused)]
-pub const MINGLING_BUILD_FULL: bool = false;
-
-/// Whether the `build_full` feature is enabled
-/// Current: `enabled`
-#[cfg(feature = "build_full")]
-#[allow(unused)]
-pub const MINGLING_BUILD_FULL: bool = true;
-/// Whether the `builds` feature is enabled
-/// Current: `disabled`
-#[cfg(not(feature = "builds"))]
-#[allow(unused)]
-pub const MINGLING_BUILDS: bool = false;
-
-/// Whether the `builds` feature is enabled
-/// Current: `enabled`
-#[cfg(feature = "builds")]
-#[allow(unused)]
-pub const MINGLING_BUILDS: bool = true;
 /// Whether the `clap` feature is enabled
 /// Current: `disabled`
 #[cfg(not(feature = "clap"))]
diff --git a/mingling/src/lib.rs b/mingling/src/lib.rs
index 55240e5..45c8ec3 100644
--- a/mingling/src/lib.rs
+++ b/mingling/src/lib.rs
@@ -64,6 +64,10 @@ pub mod macros {
     #[cfg(feature = "picker")]
     pub use arg_picker::macros::*;
     pub use mingling_macros::buffer;
+    #[cfg(feature = "comp")]
+    pub use mingling_macros::build_comp;
+    #[cfg(feature = "pathf")]
+    pub use mingling_macros::build_pathf;
     pub use mingling_macros::chain;
     #[cfg(feature = "extras")]
     pub use mingling_macros::command;