refactor(core&cli): activate default features in build script instead of CLI

.changes/feature-flags-build-script.md

@@ -0,0 +1,7 @@
+---
+'tauri-cli': 'patch:enhance'
+'@tauri-apps/cli': 'patch:enhance'
+'tauri': 'patch:enhance'
+---
+
+Set Cargo feature flags in tauri build script instead of relying on the CLI.

crates/tauri-cli/src/build.rs

@@ -189,7 +189,8 @@ pub fn setup(
     .features
     .get_or_insert(Vec::new())
     .extend(config_.build.features.clone().unwrap_or_default());
-  interface.build_options(&mut options.args, &mut options.features, mobile);
+
+  interface.build_options(&mut options.args, mobile);
 
   Ok(())
 }

crates/tauri-cli/src/interface/rust.rs

@@ -362,29 +362,11 @@ fn lookup<F: FnMut(FileType, PathBuf)>(dir: &Path, mut f: F) {
   }
 }
 
-fn shared_options(
-  mobile: bool,
-  args: &mut Vec<String>,
-  features: &mut Option<Vec<String>>,
-  app_settings: &RustAppSettings,
-) {
+fn shared_options(mobile: bool, args: &mut Vec<String>) {
   if mobile {
     args.push("--lib".into());
-    features
-      .get_or_insert(Vec::new())
-      .push("tauri/rustls-tls".into());
   } else {
     args.push("--bins".into());
-    let all_features = app_settings
-      .manifest
-      .lock()
-      .unwrap()
-      .all_enabled_features(if let Some(f) = features { f } else { &[] });
-    if !all_features.contains(&"tauri/rustls-tls".into()) {
-      features
-        .get_or_insert(Vec::new())
-        .push("tauri/native-tls".into());
-    }
   }
 }
 
@@ -408,7 +390,7 @@ fn dev_options(
   }
   *args = dev_args;
 
-  shared_options(mobile, args, features, app_settings);
+  shared_options(mobile, args);
 
   if !args.contains(&"--no-default-features".into()) {
     let manifest_features = app_settings.manifest.lock().unwrap().features();
@@ -479,16 +461,8 @@ fn get_watch_folders() -> crate::Result<Vec<PathBuf>> {
 }
 
 impl Rust {
-  pub fn build_options(
-    &self,
-    args: &mut Vec<String>,
-    features: &mut Option<Vec<String>>,
-    mobile: bool,
-  ) {
-    features
-      .get_or_insert(Vec::new())
-      .push("tauri/custom-protocol".into());
-    shared_options(mobile, args, features, &self.app_settings);
+  pub fn build_options(&self, args: &mut Vec<String>, mobile: bool) {
+    shared_options(mobile, args);
   }
 
   fn run_dev<F: Fn(Option<i32>, ExitReason) + Send + Sync + 'static>(

crates/tauri-cli/src/interface/rust/desktop.rs

@@ -178,7 +178,7 @@ fn build_dev_app<F: FnOnce(Option<i32>, ExitReason) + Send + 'static>(
   config_features: Vec<String>,
   on_exit: F,
 ) -> crate::Result<Arc<SharedChild>> {
-  let mut build_cmd = build_command(options, available_targets, config_features)?;
+  let mut build_cmd = build_command(options, available_targets, config_features, true)?;
   let runner = build_cmd.get_program().to_string_lossy().into_owned();
   build_cmd
     .env(
@@ -267,7 +267,7 @@ fn build_production_app(
   available_targets: &mut Option<Vec<RustupTarget>>,
   config_features: Vec<String>,
 ) -> crate::Result<()> {
-  let mut build_cmd = build_command(options, available_targets, config_features)?;
+  let mut build_cmd = build_command(options, available_targets, config_features, false)?;
   let runner = build_cmd.get_program().to_string_lossy().into_owned();
   match build_cmd.piped() {
     Ok(status) if status.success() => Ok(()),
@@ -289,6 +289,7 @@ fn build_command(
   options: Options,
   available_targets: &mut Option<Vec<RustupTarget>>,
   config_features: Vec<String>,
+  dev: bool,
 ) -> crate::Result<Command> {
   let runner = options.runner.unwrap_or_else(|| "cargo".into());
 
@@ -308,6 +309,16 @@ fn build_command(
   if let Some(f) = options.features {
     features.extend(f);
   }
+  // custom-protocol is handled in tauri's build.rs script
+  // which makes `cargo build` same as `tauri dev`
+  // and `cargo build --release` same as `tauri build`
+  // but for `tauri build --debug` we need to build the code
+  // in `debug` profile and activate `custom-protocol` feature.
+  let custom_protocol_feat = "tauri/custom-protocol".to_string();
+  if !dev && !features.contains(&custom_protocol_feat) {
+    features.push(custom_protocol_feat);
+  }
+
   if !features.is_empty() {
     args.push("--features".into());
     args.push(features.join(","));

crates/tauri-cli/src/mobile/android/build.rs

@@ -112,7 +112,7 @@ pub fn command(options: Options, noise_level: NoiseLevel) -> Result<()> {
     let tauri_config_ = tauri_config_guard.as_ref().unwrap();
 
     let interface = AppInterface::new(tauri_config_, build_options.target.clone())?;
-    interface.build_options(&mut Vec::new(), &mut build_options.features, true);
+    interface.build_options(&mut Vec::new(), true);
 
     let app = get_app(MobileTarget::Android, tauri_config_, &interface);
     let (config, metadata) = get_config(

crates/tauri-cli/src/mobile/ios/build.rs

@@ -151,7 +151,7 @@ pub fn command(options: Options, noise_level: NoiseLevel) -> Result<()> {
     let tauri_config_ = tauri_config_guard.as_ref().unwrap();
 
     let interface = AppInterface::new(tauri_config_, build_options.target.clone())?;
-    interface.build_options(&mut Vec::new(), &mut build_options.features, true);
+    interface.build_options(&mut Vec::new(), true);
 
     let app = get_app(MobileTarget::Ios, tauri_config_, &interface);
     let (config, _metadata) = get_config(

crates/tauri/build.rs

@@ -226,18 +226,41 @@ fn alias(alias: &str, has_feature: bool) {
 }
 
 fn main() {
-  let custom_protocol = has_feature("custom-protocol");
+  let target_os = std::env::var("CARGO_CFG_TARGET_OS").unwrap();
+  let mobile = target_os == "ios" || target_os == "android";
+  alias("desktop", !mobile);
+  alias("mobile", mobile);
+
+  let has_default = has_feature("default");
+
+  // a workaround for default features activation based on target platform
+  // https://github.com/rust-lang/cargo/issues/1197
+  if has_default
+    && ["native-tls", "native-tls-vendored", "rustls-tls"]
+      .iter()
+      .all(|f| !has_feature(f))
+  {
+    if mobile {
+      println!("cargo:rustc-cfg=feature=\"rustls-tls\"");
+    } else {
+      println!("cargo:rustc-cfg=feature=\"native-tls\"");
+    }
+  }
+
+  // a workaround for default features activation based on profile
+  let custom_protocol = if has_default && env::var("PROFILE").as_deref() == Ok("release") {
+    println!("cargo:rustc-cfg=feature=\"custom-protocol\"");
+    true
+  } else {
+    has_feature("custom-protocol")
+  };
+
   let dev = !custom_protocol;
   alias("custom_protocol", custom_protocol);
   alias("dev", dev);
 
   println!("cargo:dev={dev}");
 
-  let target_os = std::env::var("CARGO_CFG_TARGET_OS").unwrap();
-  let mobile = target_os == "ios" || target_os == "android";
-  alias("desktop", !mobile);
-  alias("mobile", mobile);
-
   let out_dir = PathBuf::from(env::var("OUT_DIR").unwrap());
 
   let checked_features_out_path = out_dir.join("checked_features");