Allow to specify which components are built

Add `$ESP_IDF_COMPONENTS` and `esp_idf_components` configuration option that allow
to specify a list of esp-idf components to build. This list can be used to trim down the esp-idf
build and reduce compile time.
Only implemented for the native build driver.
Fixes #83

README.md

@@ -272,6 +272,19 @@ The following configuration options are available:
    > ⚠️
    > [Older ESP-IDF versions might not support all MCUs from above.](https://github.com/espressif/esp-idf#esp-idf-release-and-soc-compatibility)
    
+- ### *`esp_idf_components`*, `$ESP_IDF_COMPONENTS` (*native* builder only)
+
+    The list of esp-idf components (names) that should be built. This list is used to
+    trim the esp-idf build. Any component that is a dependency of a component in this
+    list will also automatically be built.
+
+    Defaults to all components being built.
+
+    > 🛈 **Note**  
+    > Some components must be explicitly enabled in the sdkconfig.  
+    > [Extra components](#extra-esp-idf-components) must also be added to this list if
+    > they are to be built.
+
 ### Example
 
 An example of the `[package.metadata.esp-idf-sys]` section of the `Cargo.toml`.

build/config.rs

@@ -23,7 +23,7 @@ pub struct BuildConfig {
     esp_idf_sdkconfig: Option<PathBuf>,
 
     /// One or more paths to sdkconfig.defaults files used by the esp-idf.
-    #[serde(deserialize_with = "parse::sdkconfig_defaults")]
+    #[serde(deserialize_with = "parse::list")]
     esp_idf_sdkconfig_defaults: Option<Vec<PathBuf>>,
 
     /// The MCU (esp32, esp32s2, esp32s3, esp32c3, ...) to compile for if unset will be
@@ -173,21 +173,22 @@ where
     }
 }
 
-mod parse {
-    use std::path::PathBuf;
-
+pub mod parse {
     use serde::{Deserialize, Deserializer};
 
     use super::utils::ValueOrVec;
 
-    pub fn sdkconfig_defaults<'d, D: Deserializer<'d>>(
-        de: D,
-    ) -> Result<Option<Vec<PathBuf>>, D::Error> {
-        Option::<ValueOrVec<String, PathBuf>>::deserialize(de).map(|val| match val {
+    /// Parse a string into a `;`-separated list of `T`s or parse a list of `T`s directly.
+    pub fn list<'d, T, D>(de: D) -> Result<Option<Vec<T>>, D::Error>
+    where
+        D: Deserializer<'d>,
+        T: for<'s> From<&'s str> + Deserialize<'d>,
+    {
+        Option::<ValueOrVec<String, T>>::deserialize(de).map(|val| match val {
             Some(ValueOrVec::Val(s)) => Some(
                 s.split(';')
                     .filter(|s| !s.is_empty())
-                    .map(PathBuf::from)
+                    .map(Into::into)
                     .collect(),
             ),
             Some(ValueOrVec::Vec(v)) => Some(v),

build/native/cargo_driver.rs

@@ -317,6 +317,11 @@ pub fn build() -> Result<EspIdfBuildOutput> {
         cmake_config.env("IDF_TOOLS_PATH", install_dir);
     }
 
+    // specify the components that should be built
+    if let Some(components) = &config.native.esp_idf_components {
+        cmake_config.env("COMPONENTS", components.join(";"));
+    }
+
     // Build the esp-idf.
     cmake_config.build();
 
@@ -373,6 +378,8 @@ pub fn build() -> Result<EspIdfBuildOutput> {
         })
         .collect::<Vec<_>>();
 
+    eprintln!("Built components: {}", components.join(", "));
+
     let sdkconfig_json = path_buf![&cmake_build_dir, "config", "sdkconfig.json"];
     let build_output = EspIdfBuildOutput {
         cincl_args: build::CInclArgs::try_from(&target.compile_groups[0])?,

build/native/cargo_driver/config.rs

@@ -48,8 +48,19 @@ pub struct NativeConfig {
     ///
     /// Can be specified in the root crate's `package.metadata.esp-idf-sys` and all direct
     /// dependencies'.
+    ///
+    /// This option is not available as an environment variable.
     #[serde(alias = "extra-components")]
     pub extra_components: Vec<ExtraComponent>,
+
+    /// A list of esp-idf components (names) that should be built. This list is used to
+    /// trim the esp-idf build. Any component that is a dependency of a component in this
+    /// list will also automatically be built.
+    ///
+    /// If this option is not specified, all components will be built. Note though that
+    /// some components must be explicitly enabled in the sdkconfig.
+    #[serde(default, deserialize_with = "parse::list")]
+    pub esp_idf_components: Option<Vec<String>>,
 }
 
 impl NativeConfig {
@@ -181,13 +192,15 @@ impl NativeConfig {
                     esp_idf_cmake_generator,
                     idf_path,
                     extra_components,
+                    esp_idf_components,
                 },
         } = EspIdfSys::deserialize(&root.metadata)?;
 
         set_when_none(&mut self.esp_idf_version, esp_idf_version);
         set_when_none(&mut self.esp_idf_repository, esp_idf_repository);
         set_when_none(&mut self.esp_idf_cmake_generator, esp_idf_cmake_generator);
         set_when_none(&mut self.idf_path, idf_path);
+        set_when_none(&mut self.esp_idf_components, esp_idf_components);
 
         fn make_processor(
             package: &Package,
@@ -317,6 +330,7 @@ mod parse {
     use strum::IntoEnumIterator;
 
     use super::*;
+    pub use crate::config::parse::*;
     use crate::config::utils::ValueOrVec;
 
     /// Parse a cmake generator, either `default` or one of [`cmake::Generator`].

resources/cmake_project/CMakeLists.txt

@@ -8,7 +8,12 @@ foreach(component_dir IN ITEMS $ENV{EXTRA_COMPONENT_DIRS})
     idf_build_component(${component_dir})
 endforeach()
 
-idf_build_process($ENV{IDF_TARGET} SDKCONFIG $ENV{SDKCONFIG} SDKCONFIG_DEFAULTS $ENV{SDKCONFIG_DEFAULTS})
+if(DEFINED ENV{COMPONENTS})
+    idf_build_process($ENV{IDF_TARGET} SDKCONFIG $ENV{SDKCONFIG} SDKCONFIG_DEFAULTS $ENV{SDKCONFIG_DEFAULTS} COMPONENTS $ENV{COMPONENTS})
+else()
+    idf_build_process($ENV{IDF_TARGET} SDKCONFIG $ENV{SDKCONFIG} SDKCONFIG_DEFAULTS $ENV{SDKCONFIG_DEFAULTS})
+endif()
+
 idf_build_get_property(aliases BUILD_COMPONENT_ALIASES)
 
 add_executable(libespidf.elf main.c)