Add support for PlatformIO platform = native

cargo-pio/src/main.rs

@@ -341,7 +341,7 @@ fn main() -> Result<()> {
                     "linkflags" => scons_vars.linkflags,
                     "link" => scons_vars.link,
                     "linkcom" => scons_vars.linkcom,
-                    "mcu" => scons_vars.mcu,
+                    "mcu" => format!("{:?}", scons_vars.mcu),
                     "clangargs" => scons_vars.clangargs.unwrap_or_else(|| "".into()),
                     _ => panic!(),
                 };

src/bindgen.rs

@@ -40,7 +40,7 @@ impl Factory {
         Ok(Self {
             clang_args,
             linker: Some(scons_vars.full_path(scons_vars.link.clone())?),
-            mcu: Some(scons_vars.mcu.clone()),
+            mcu: scons_vars.mcu.clone(),
             force_cpp: false,
             sysroot: None,
         })

src/cargo.rs

@@ -106,7 +106,11 @@ impl Crate {
         }
     }
 
-    /// Create a `config.toml` in `.cargo` with a `[target]` and `[unstable]` section.
+    /// Create a `config.toml` in `.cargo` with an `[unstable]` section, and a `[build] target`
+    /// if a `target` is given.
+    ///
+    /// `[build] target` changes the default `cargo --target`, so it should only be used when the
+    /// default target is unwanted.
     pub fn create_config_toml(
         &self,
         target: Option<impl AsRef<str>>,

src/pio/project.rs

@@ -61,11 +61,11 @@ pub struct SconsVariables {
     pub linkflags: String,
     pub link: String,
     pub linkcom: String,
-    pub mcu: String,
+    pub mcu: Option<String>,
     pub clangargs: Option<String>,
 
-    pub pio_platform_dir: String,
-    pub pio_framework_dir: String,
+    pub pio_platform_dir: Option<String>,
+    pub pio_framework_dir: Option<String>,
 }
 
 impl SconsVariables {
@@ -83,11 +83,11 @@ impl SconsVariables {
                 linkflags: env::var(VAR_BUILD_LINK_FLAGS).ok()?,
                 link: env::var(VAR_BUILD_LINK).ok()?,
                 linkcom: env::var(VAR_BUILD_LINKCOM).ok()?,
-                mcu: env::var(VAR_BUILD_MCU).ok()?,
+                mcu: env::var(VAR_BUILD_MCU).ok(),
                 clangargs: env::var(VAR_BUILD_BINDGEN_EXTRA_CLANG_ARGS).ok(),
 
-                pio_platform_dir: env::var(VAR_BUILD_PIO_PLATFORM_DIR).ok()?,
-                pio_framework_dir: env::var(VAR_BUILD_PIO_FRAMEWORK_DIR).ok()?,
+                pio_platform_dir: env::var(VAR_BUILD_PIO_PLATFORM_DIR).ok(),
+                pio_framework_dir: env::var(VAR_BUILD_PIO_FRAMEWORK_DIR).ok(),
             })
         } else {
             None
@@ -313,7 +313,10 @@ impl Builder {
                     )?;
 
                     let rust_lib = cargo_crate.set_library_type(["staticlib"])?;
-                    cargo_crate.create_config_toml(Some(resolution.target.clone()), build_std)?;
+
+                    // No `[build] target`, because it would change the default target used when
+                    // running `cargo` without `--target`, which `platform = native` relies on.
+                    cargo_crate.create_config_toml(None::<&str>, build_std)?;
 
                     if arduino {
                         self.create_file(PathBuf::from("src").join("lib.rs"), LIB_ARDUINO_RS)?;

src/pio/resources/platformio.cargo.py.resource

@@ -27,7 +27,7 @@ class Cargo:
         self.__cargo_ran = False
 
         self.__rust_lib = env.GetProjectOption("rust_lib")
-        self.__rust_target = env.GetProjectOption("rust_target")
+        self.__rust_target = env.GetProjectOption("rust_target", default = None)
 
         self.__rust_bindgen_enabled = env.GetProjectOption("rust_bindgen_enabled", default = "false").lower() == "true"
         self.__rust_bindgen_extra_clang_args = env.GetProjectOption("rust_bindgen_extra_clang_args", default = "")
@@ -66,25 +66,40 @@ class Cargo:
         env["ENV"]["CARGO_PIO_BUILD_LINK_FLAGS"] = env.subst("$LINKFLAGS")
         env["ENV"]["CARGO_PIO_BUILD_LINK"] = env.subst("$LINK")
         env["ENV"]["CARGO_PIO_BUILD_LINKCOM"] = env.subst("$LINKCOM")
-        env["ENV"]["CARGO_PIO_BUILD_MCU"] = board_mcu
+        if board_mcu is not None:
+            env["ENV"]["CARGO_PIO_BUILD_MCU"] = board_mcu
 
         if self.__rust_bindgen_enabled:
             env["ENV"]["CARGO_PIO_BUILD_BINDGEN_RUN"] = "True"
             env["ENV"]["CARGO_PIO_BUILD_BINDGEN_EXTRA_CLANG_ARGS"] = self.__rust_bindgen_extra_clang_args
 
-        env["ENV"]["CARGO_PIO_BUILD_PIO_PLATFORM_DIR"] = env.PioPlatform().get_dir()[0]
-        env["ENV"]["CARGO_PIO_BUILD_PIO_FRAMEWORK_DIR"] = env.PioPlatform().get_package_dir(env.PioPlatform().frameworks[env.GetProjectOption("framework")[0]]["package"])
+        pio_platform_dir = env.PioPlatform().get_dir()[0]
+        if pio_platform_dir is not None:
+            env["ENV"]["CARGO_PIO_BUILD_PIO_PLATFORM_DIR"] = pio_platform_dir
+        framework = env.GetProjectOption("framework")
+        if framework:
+            pio_framework_dir = env.PioPlatform().get_package_dir(env.PioPlatform().frameworks[framework[0]]["package"])
+            if pio_framework_dir is not None:
+                env["ENV"]["CARGO_PIO_BUILD_PIO_FRAMEWORK_DIR"] = pio_framework_dir
+        if self.__rust_target is not None:
+            cargo_target_option = f"--target {self.__rust_target}"
+        else:
+            cargo_target_option = ""
 
         self.__cargo_ran = True
-        result = env.Execute(f"cargo build {'--release' if self.__cargo_profile == 'release' else ''} --lib --target {self.__rust_target} {self.__cargo_options}")
+        result = env.Execute(f"cargo build {'--release' if self.__cargo_profile == 'release' else ''} --lib {cargo_target_option} {self.__cargo_options}")
 
         print("<<< CARGO")
 
         return result
 
     def __link_cargo(self, source, target, env):
         env.Prepend(LINKFLAGS = ["-Wl,--allow-multiple-definition"]) # A hack to workaround this issue with Rust's compiler intrinsics: https://github.com/rust-lang/compiler-builtins/issues/353
-        env.Prepend(LIBPATH = [env.subst(os.path.join(self.__cargo_target_dir, self.__rust_target, self.__cargo_profile))])
+        if self.__rust_target is not None:
+            cargo_profile_path = os.path.join(self.__cargo_target_dir, self.__rust_target, self.__cargo_profile)
+        else:
+            cargo_profile_path = os.path.join(self.__cargo_target_dir, self.__cargo_profile)
+        env.Prepend(LIBPATH = [env.subst(cargo_profile_path)])
         env.Prepend(LIBS = [self.__rust_lib])
 
 Cargo().run(env)