feat: Support passing multiple targets to cargo (for Rust 1.64.0+)

Author: poliorcetics

crates/flycheck/src/lib.rs

@@ -25,7 +25,7 @@ pub use cargo_metadata::diagnostic::{
 pub enum FlycheckConfig {
     CargoCommand {
         command: String,
-        target_triple: Option<String>,
+        target_triples: Vec<String>,
         all_targets: bool,
         no_default_features: bool,
         all_features: bool,
@@ -262,7 +262,7 @@ impl FlycheckActor {
         let mut cmd = match &self.config {
             FlycheckConfig::CargoCommand {
                 command,
-                target_triple,
+                target_triples,
                 no_default_features,
                 all_targets,
                 all_features,
@@ -276,7 +276,7 @@ impl FlycheckActor {
                 cmd.args(&["--workspace", "--message-format=json", "--manifest-path"])
                     .arg(self.workspace_root.join("Cargo.toml").as_os_str());
 
-                if let Some(target) = target_triple {
+                for target in target_triples {
                     cmd.args(&["--target", target.as_str()]);
                 }
                 if *all_targets {

crates/project-model/src/build_scripts.rs

@@ -52,7 +52,7 @@ impl WorkspaceBuildScripts {
         cmd.args(&["check", "--quiet", "--workspace", "--message-format=json"]);
 
         // --all-targets includes tests, benches and examples in addition to the
-        // default lib and bins. This is an independent concept from the --targets
+        // default lib and bins. This is an independent concept from the --target
         // flag below.
         cmd.arg("--all-targets");
 

crates/project-model/src/cargo_workspace.rs

@@ -268,11 +268,7 @@ impl CargoWorkspace {
         config: &CargoConfig,
         progress: &dyn Fn(String),
     ) -> Result<cargo_metadata::Metadata> {
-        let target = config
-            .target
-            .clone()
-            .or_else(|| cargo_config_build_target(cargo_toml, &config.extra_env))
-            .or_else(|| rustc_discover_host_triple(cargo_toml, &config.extra_env));
+        let targets = find_list_of_build_targets(config, cargo_toml);
 
         let mut meta = MetadataCommand::new();
         meta.cargo_path(toolchain::cargo());
@@ -294,8 +290,12 @@ impl CargoWorkspace {
         }
         meta.current_dir(current_dir.as_os_str());
 
-        if let Some(target) = target {
-            meta.other_options(vec![String::from("--filter-platform"), target]);
+        if !targets.is_empty() {
+            let other_options: Vec<_> = targets
+                .into_iter()
+                .flat_map(|target| ["--filter-platform".to_string(), target])
+                .collect();
+            meta.other_options(other_options);
         }
 
         // FIXME: Fetching metadata is a slow process, as it might require
@@ -465,6 +465,19 @@ impl CargoWorkspace {
     }
 }
 
+fn find_list_of_build_targets(config: &CargoConfig, cargo_toml: &ManifestPath) -> Vec<String> {
+    if let Some(target) = &config.target {
+        return [target.into()].to_vec();
+    }
+
+    let build_targets = cargo_config_build_target(cargo_toml, &config.extra_env);
+    if !build_targets.is_empty() {
+        return build_targets;
+    }
+
+    rustc_discover_host_triple(cargo_toml, &config.extra_env).into_iter().collect()
+}
+
 fn rustc_discover_host_triple(
     cargo_toml: &ManifestPath,
     extra_env: &FxHashMap<String, String>,
@@ -495,20 +508,29 @@ fn rustc_discover_host_triple(
 fn cargo_config_build_target(
     cargo_toml: &ManifestPath,
     extra_env: &FxHashMap<String, String>,
-) -> Option<String> {
+) -> Vec<String> {
     let mut cargo_config = Command::new(toolchain::cargo());
     cargo_config.envs(extra_env);
     cargo_config
         .current_dir(cargo_toml.parent())
         .args(&["-Z", "unstable-options", "config", "get", "build.target"])
         .env("RUSTC_BOOTSTRAP", "1");
     // if successful we receive `build.target = "target-triple"`
+    // or `build.target = ["<target 1>", ..]`
     tracing::debug!("Discovering cargo config target by {:?}", cargo_config);
-    match utf8_stdout(cargo_config) {
-        Ok(stdout) => stdout
-            .strip_prefix("build.target = \"")
-            .and_then(|stdout| stdout.strip_suffix('"'))
-            .map(ToOwned::to_owned),
-        Err(_) => None,
+    utf8_stdout(cargo_config).map(parse_output_cargo_config_build_target).unwrap_or_default()
+}
+
+fn parse_output_cargo_config_build_target(stdout: String) -> Vec<String> {
+    let trimmed = stdout.trim_start_matches("build.target = ").trim_matches('"');
+
+    if !trimmed.starts_with('[') {
+        return [trimmed.to_string()].to_vec();
+    }
+
+    let res = serde_json::from_str(trimmed);
+    if let Err(e) = &res {
+        tracing::warn!("Failed to parse `build.target` as an array of target: {}`", e);
     }
+    res.unwrap_or_default()
 }

crates/rust-analyzer/src/config.rs

@@ -102,6 +102,8 @@ config_data! {
         /// This option does not take effect until rust-analyzer is restarted.
         cargo_sysroot: Option<String>    = "\"discover\"",
         /// Compilation target override (target triple).
+        // FIXME(@poliorcetics): move to multiple targets here too, but this will need more work
+        // than `checkOnSave_target`
         cargo_target: Option<String>     = "null",
         /// Unsets `#[cfg(test)]` for the specified crates.
         cargo_unsetTest: Vec<String>     = "[\"core\"]",
@@ -144,9 +146,9 @@ config_data! {
         /// ```
         /// .
         checkOnSave_overrideCommand: Option<Vec<String>> = "null",
-        /// Check for a specific target. Defaults to
+        /// Check for specific targets. Defaults to
         /// `#rust-analyzer.cargo.target#`.
-        checkOnSave_target: Option<String>               = "null",
+        checkOnSave_target: Vec<String>                  = "[]",
 
         /// Toggles the additional completions that automatically add imports when completed.
         /// Note that your client must specify the `additionalTextEdits` LSP client capability to truly have this feature enabled.
@@ -1091,11 +1093,10 @@ impl Config {
             }
             Some(_) | None => FlycheckConfig::CargoCommand {
                 command: self.data.checkOnSave_command.clone(),
-                target_triple: self
-                    .data
-                    .checkOnSave_target
-                    .clone()
-                    .or_else(|| self.data.cargo_target.clone()),
+                target_triples: match self.data.checkOnSave_target.is_empty() {
+                    false => self.data.checkOnSave_target.clone(),
+                    true => self.data.cargo_target.clone().into_iter().collect(),
+                },
                 all_targets: self.data.checkOnSave_allTargets,
                 no_default_features: self
                     .data

docs/user/generated_config.adoc

@@ -146,10 +146,10 @@ cargo check --workspace --message-format=json --all-targets
 ```
 .
 --
-[[rust-analyzer.checkOnSave.target]]rust-analyzer.checkOnSave.target (default: `null`)::
+[[rust-analyzer.checkOnSave.target]]rust-analyzer.checkOnSave.target (default: `[]`)::
 +
 --
-Check for a specific target. Defaults to
+Check for specific targets. Defaults to
 `#rust-analyzer.cargo.target#`.
 --
 [[rust-analyzer.completion.autoimport.enable]]rust-analyzer.completion.autoimport.enable (default: `true`)::

editors/code/package.json

@@ -566,12 +566,12 @@
                     }
                 },
                 "rust-analyzer.checkOnSave.target": {
-                    "markdownDescription": "Check for a specific target. Defaults to\n`#rust-analyzer.cargo.target#`.",
-                    "default": null,
-                    "type": [
-                        "null",
-                        "string"
-                    ]
+                    "markdownDescription": "Check for specific targets. Defaults to\n`#rust-analyzer.cargo.target#`.",
+                    "default": [],
+                    "type": "array",
+                    "items": {
+                        "type": "string"
+                    }
                 },
                 "rust-analyzer.completion.autoimport.enable": {
                     "markdownDescription": "Toggles the additional completions that automatically add imports when completed.\nNote that your client must specify the `additionalTextEdits` LSP client capability to truly have this feature enabled.",