fix(codegen): use TAURI_ENV_TARGET_TRIPLE to determine the current platform-specific config (#9646)

* fix(codegen): use `TAURI_ENV_TARGET_TRIPLE` to determine the current platform-specific config

* set env var

* Update .changes/tauri-codegen-use-correct-env.md

---------

Co-authored-by: Lucas Nogueira <lucas@tauri.app>

.changes/tauri-codegen-use-correct-env.md

@@ -0,0 +1,5 @@
+---
+"tauri-codegen": "patch"
+---
+
+Use `TAURI_ENV_TARGET_TRIPLE` (which is set by `tauri-build`) to determine the target when reading the config file.

.changes/tauri-correct-platform-file.md

@@ -0,0 +1,6 @@
+---
+"tauri": "patch:bug"
+---
+
+Parse the correct platform `tauri.<platform>.conf.json` config file when building or developing for mobile.
+

core/tauri-build/src/lib.rs

@@ -530,6 +530,8 @@ pub fn try_build(attributes: Attributes) -> Result<()> {
   tauri_utils::plugin::load_global_api_scripts(&out_dir);
 
   println!("cargo:rustc-env=TAURI_ENV_TARGET_TRIPLE={target_triple}");
+  // when running codegen in this build script, we need to access the env var directly
+  std::env::set_var("TAURI_ENV_TARGET_TRIPLE", &target_triple);
 
   // TODO: far from ideal, but there's no other way to get the target dir, see <https://github.com/rust-lang/cargo/issues/5457>
   let target_dir = out_dir

core/tauri-codegen/src/context.rs

@@ -139,8 +139,7 @@ pub fn context_codegen(data: ContextData) -> Result<TokenStream, EmbeddedAssetsE
     assets,
   } = data;
 
-  let target = std::env::var("TARGET")
-    .or_else(|_| std::env::var("TAURI_ENV_TARGET_TRIPLE"))
+  let target = std::env::var("TAURI_ENV_TARGET_TRIPLE")
     .as_deref()
     .map(Target::from_triple)
     .unwrap_or_else(|_| Target::current());

core/tauri-codegen/src/lib.rs

@@ -18,6 +18,7 @@ use std::{
   path::{Path, PathBuf},
 };
 pub use tauri_utils::config::{parse::ConfigError, Config};
+use tauri_utils::platform::Target;
 
 mod context;
 pub mod embedded_assets;
@@ -63,22 +64,28 @@ pub fn get_config(path: &Path) -> Result<(Config, PathBuf), CodegenConfigError>
     .map(ToOwned::to_owned)
     .ok_or_else(|| CodegenConfigError::Parent(path.into_owned()))?;
 
+  let target = std::env::var("TAURI_ENV_TARGET_TRIPLE")
+    .as_deref()
+    .map(Target::from_triple)
+    .unwrap_or_else(|_| Target::current());
+
   // in the future we may want to find a way to not need the TAURI_CONFIG env var so that
   // it is impossible for the content of two separate configs to get mixed up. The chances are
   // already unlikely unless the developer goes out of their way to run the cli on a different
   // project than the target crate.
   let mut config = serde_json::from_value(tauri_utils::config::parse::read_from(
-    tauri_utils::platform::Target::current(),
+    target,
     parent.clone(),
   )?)?;
+
   if let Ok(env) = std::env::var("TAURI_CONFIG") {
     let merge_config: serde_json::Value =
       serde_json::from_str(&env).map_err(CodegenConfigError::FormatInline)?;
     json_patch::merge(&mut config, &merge_config);
   }
 
-  let old_cwd = std::env::current_dir().map_err(CodegenConfigError::CurrentDir)?;
   // Set working directory to where `tauri.config.json` is, so that relative paths in it are parsed correctly.
+  let old_cwd = std::env::current_dir().map_err(CodegenConfigError::CurrentDir)?;
   std::env::set_current_dir(parent.clone()).map_err(CodegenConfigError::CurrentDir)?;
 
   let config = serde_json::from_value(config)?;

tooling/bundler/src/bundle/windows/msi/wix.rs

@@ -586,9 +586,9 @@ pub fn build_wix_app_installer(
     data.insert("feature_group_refs", to_json(&wix.feature_group_refs));
     data.insert("feature_refs", to_json(&wix.feature_refs));
     data.insert("merge_refs", to_json(&wix.merge_refs));
-    fragment_paths = wix.fragment_paths.clone();
+    fragment_paths.clone_from(&wix.fragment_paths);
     enable_elevated_update_task = wix.enable_elevated_update_task;
-    custom_template_path = wix.template.clone();
+    custom_template_path.clone_from(&wix.template);
 
     if let Some(banner_path) = &wix.banner_path {
       let filename = banner_path