feat: traverse the target directory instead of intercepting the linker to collect assets (#3228)

* feat: simply traverse the filesystem instead of intercepting the linker

* handle LTO approach too

* typo...

* add deeplinker just in case

packages/cli/src/assets.rs

@@ -24,8 +24,8 @@ impl AssetManifest {
     }
 
     /// Fill this manifest with a file object/rlib files, typically extracted from the linker intercepted
-    pub(crate) fn add_from_object_path(&mut self, path: PathBuf) -> anyhow::Result<()> {
-        let data = std::fs::read(path.clone())?;
+    pub(crate) fn add_from_object_path(&mut self, path: &Path) -> anyhow::Result<()> {
+        let data = std::fs::read(path)?;
 
         match path.extension().and_then(|ext| ext.to_str()) {
             // Parse an rlib as a collection of objects

packages/cli/src/build/request.rs

@@ -6,7 +6,12 @@ use crate::{link::LinkAction, BuildArgs};
 use crate::{AppBundle, Platform};
 use anyhow::Context;
 use serde::Deserialize;
-use std::{path::PathBuf, process::Stdio, time::Instant};
+use std::{
+    ffi::OsStr,
+    path::{Path, PathBuf},
+    process::Stdio,
+    time::Instant,
+};
 use tokio::{io::AsyncBufReadExt, process::Command};
 
 #[derive(Clone, Debug)]
@@ -60,7 +65,7 @@ impl BuildRequest {
         let start = Instant::now();
         self.prepare_build_dir()?;
         let exe = self.build_cargo().await?;
-        let assets = self.collect_assets().await?;
+        let assets = self.collect_assets(&exe).await?;
 
         Ok(BuildArtifacts {
             exe,
@@ -102,9 +107,6 @@ impl BuildRequest {
             .args(self.build_arguments())
             .envs(self.env_vars()?);
 
-        // todo(jon): save the temps into a file that we use for asset extraction instead of the weird double compile.
-        // .args(["--", "-Csave-temps=y"]);
-
         if let Some(target_dir) = self.custom_target_dir.as_ref() {
             cmd.env("CARGO_TARGET_DIR", target_dir);
         }
@@ -203,19 +205,54 @@ impl BuildRequest {
         Ok(out_location)
     }
 
-    /// Run the linker intercept and then fill in our AssetManifest from the incremental artifacts
+    /// Traverse the target directory and collect all assets from the incremental cache
     ///
-    /// This will execute `dx` with an env var set to force `dx` to operate as a linker, and then
-    /// traverse the .o and .rlib files rustc passes that new `dx` instance, collecting the link
-    /// tables marked by manganis and parsing them as a ResourceAsset.
-    pub(crate) async fn collect_assets(&self) -> Result<AssetManifest> {
+    /// This uses "known paths" that have stayed relatively stable during cargo's lifetime.
+    /// One day this system might break and we might need to go back to using the linker approach.
+    pub(crate) async fn collect_assets(&self, exe: &Path) -> Result<AssetManifest> {
         tracing::debug!("Collecting assets ...");
 
         if self.build.skip_assets {
             return Ok(AssetManifest::default());
         }
 
-        self.deep_linker_asset_extract().await
+        // Experimental feature for testing - if the env var is set, we'll use the deeplinker
+        if std::env::var("DEEPLINK").is_ok() {
+            tracing::debug!("Using deeplinker instead of incremental cache");
+            return self.deep_linker_asset_extract().await;
+        }
+
+        // walk every file in the incremental cache dir, reading and inserting items into the manifest.
+        let mut manifest = AssetManifest::default();
+
+        // Add from the deps folder where the rlibs are stored for dependencies
+        let deps_folder = exe.parent().unwrap().join("deps");
+        tracing::trace!("Adding assets from deps folder: {deps_folder:?}");
+        for entry in deps_folder.read_dir()?.flatten() {
+            if entry.path().extension() == Some(OsStr::new("rlib")) {
+                _ = manifest.add_from_object_path(&entry.path());
+            }
+        }
+
+        // Add from the incremental cache folder by recursively walking the folder
+        // it seems that this sticks around no matter what - and cargo doesn't clean it up since the .os are cached anyway
+        fn recursive_add(manifest: &mut AssetManifest, path: &Path) -> Result<()> {
+            if path.extension() == Some(OsStr::new("o")) {
+                _ = manifest.add_from_object_path(path);
+            } else if let Ok(dir) = path.read_dir() {
+                for entry in dir.flatten() {
+                    recursive_add(manifest, &entry.path())?;
+                }
+            }
+
+            Ok(())
+        }
+        recursive_add(&mut manifest, &exe.parent().unwrap().join("incremental"))?;
+
+        // And then add from the exe directly, just in case it's LTO compiled and has no incremental cache
+        _ = manifest.add_from_object_path(exe);
+
+        Ok(manifest)
     }
 
     /// Create a list of arguments for cargo builds
@@ -408,6 +445,7 @@ impl BuildRequest {
     ///
     /// There's a chance that's not actually true, so this function is kept around in case we do
     /// need to revert to "deep extraction".
+    #[allow(unused)]
     async fn deep_linker_asset_extract(&self) -> Result<AssetManifest> {
         // Create a temp file to put the output of the args
         // We need to do this since rustc won't actually print the link args to stdout, so we need to
@@ -619,9 +657,7 @@ impl BuildRequest {
     /// a final build output somewhere. Some platforms have basically no build command, and can simply
     /// be ran by executing the exe directly.
     pub(crate) fn root_dir(&self) -> PathBuf {
-        let platform_dir = self
-            .krate
-            .build_dir(self.build.platform(), self.build.release);
+        let platform_dir = self.platform_dir();
 
         match self.build.platform() {
             Platform::Web => platform_dir.join("public"),
@@ -639,6 +675,11 @@ impl BuildRequest {
         }
     }
 
+    pub(crate) fn platform_dir(&self) -> PathBuf {
+        self.krate
+            .build_dir(self.build.platform(), self.build.release)
+    }
+
     pub fn asset_dir(&self) -> PathBuf {
         match self.build.platform() {
             Platform::MacOS => self

packages/cli/src/cli/link.rs

@@ -92,7 +92,7 @@ impl LinkAction {
                     if item.ends_with(".o") || item.ends_with(".rlib") {
                         let path_to_item = PathBuf::from(item);
                         if let Ok(path) = path_to_item.canonicalize() {
-                            _ = manifest.add_from_object_path(path);
+                            _ = manifest.add_from_object_path(&path);
                         }
                     }
                 }