WIP: Implementation for multiple build scripts

src/cargo/core/compiler/build_runner/mod.rs

@@ -248,23 +248,25 @@ impl<'a, 'gctx> BuildRunner<'a, 'gctx> {
                 args.extend(compiler::features_args(unit));
                 args.extend(compiler::check_cfg_args(unit));
 
-                let script_meta = self.find_build_script_metadata(unit);
-                if let Some(meta) = script_meta {
-                    if let Some(output) = self.build_script_outputs.lock().unwrap().get(meta) {
-                        for cfg in &output.cfgs {
-                            args.push("--cfg".into());
-                            args.push(cfg.into());
-                        }
+                let script_metas = self.find_build_script_metadatas(unit);
+                if let Some(meta_vec) = script_metas.clone() {
+                    for meta in meta_vec {
+                        if let Some(output) = self.build_script_outputs.lock().unwrap().get(meta) {
+                            for cfg in &output.cfgs {
+                                args.push("--cfg".into());
+                                args.push(cfg.into());
+                            }
 
-                        for check_cfg in &output.check_cfgs {
-                            args.push("--check-cfg".into());
-                            args.push(check_cfg.into());
-                        }
+                            for check_cfg in &output.check_cfgs {
+                                args.push("--check-cfg".into());
+                                args.push(check_cfg.into());
+                            }
 
-                        for (lt, arg) in &output.linker_args {
-                            if lt.applies_to(&unit.target, unit.mode) {
-                                args.push("-C".into());
-                                args.push(format!("link-arg={}", arg).into());
+                            for (lt, arg) in &output.linker_args {
+                                if lt.applies_to(&unit.target, unit.mode) {
+                                    args.push("-C".into());
+                                    args.push(format!("link-arg={}", arg).into());
+                                }
                             }
                         }
                     }
@@ -285,7 +287,7 @@ impl<'a, 'gctx> BuildRunner<'a, 'gctx> {
                     args,
                     unstable_opts,
                     linker: self.compilation.target_linker(unit.kind).clone(),
-                    script_meta,
+                    script_metas,
                     env: artifact::get_env(&self, self.unit_deps(unit))?,
                 });
             }
@@ -420,29 +422,40 @@ impl<'a, 'gctx> BuildRunner<'a, 'gctx> {
         &self.bcx.unit_graph[unit]
     }
 
-    /// Returns the `RunCustomBuild` Unit associated with the given Unit.
+    /// Returns the `RunCustomBuild` Units associated with the given Unit.
     ///
     /// If the package does not have a build script, this returns None.
-    pub fn find_build_script_unit(&self, unit: &Unit) -> Option<Unit> {
+    pub fn find_build_script_units(&self, unit: &Unit) -> Option<Vec<Unit>> {
         if unit.mode.is_run_custom_build() {
-            return Some(unit.clone());
+            return Some(vec![unit.clone()]);
         }
-        self.bcx.unit_graph[unit]
+
+        let build_script_units: Vec<Unit> = self.bcx.unit_graph[unit]
             .iter()
-            .find(|unit_dep| {
+            .filter(|unit_dep| {
                 unit_dep.unit.mode.is_run_custom_build()
                     && unit_dep.unit.pkg.package_id() == unit.pkg.package_id()
             })
             .map(|unit_dep| unit_dep.unit.clone())
+            .collect();
+        if build_script_units.is_empty() {
+            None
+        } else {
+            Some(build_script_units)
+        }
     }
 
     /// Returns the metadata hash for the `RunCustomBuild` Unit associated with
     /// the given unit.
     ///
     /// If the package does not have a build script, this returns None.
-    pub fn find_build_script_metadata(&self, unit: &Unit) -> Option<UnitHash> {
-        let script_unit = self.find_build_script_unit(unit)?;
-        Some(self.get_run_build_script_metadata(&script_unit))
+    pub fn find_build_script_metadatas(&self, unit: &Unit) -> Option<Vec<UnitHash>> {
+        self.find_build_script_units(unit).map(|units| {
+            units
+                .iter()
+                .map(|u| self.get_run_build_script_metadata(u))
+                .collect()
+        })
     }
 
     /// Returns the metadata hash for a `RunCustomBuild` unit.
@@ -480,11 +493,11 @@ impl<'a, 'gctx> BuildRunner<'a, 'gctx> {
     /// Returns a [`UnitOutput`] which represents some information about the
     /// output of a unit.
     pub fn unit_output(&self, unit: &Unit, path: &Path) -> UnitOutput {
-        let script_meta = self.find_build_script_metadata(unit);
+        let script_metas = self.find_build_script_metadatas(unit);
         UnitOutput {
             unit: unit.clone(),
             path: path.to_path_buf(),
-            script_meta,
+            script_metas,
         }
     }
 

src/cargo/core/compiler/compilation.rs

@@ -45,7 +45,7 @@ pub struct Doctest {
     /// The script metadata, if this unit's package has a build script.
     ///
     /// This is used for indexing [`Compilation::extra_env`].
-    pub script_meta: Option<UnitHash>,
+    pub script_metas: Option<Vec<UnitHash>>,
 
     /// Environment variables to set in the rustdoc process.
     pub env: HashMap<String, OsString>,
@@ -61,7 +61,7 @@ pub struct UnitOutput {
     /// The script metadata, if this unit's package has a build script.
     ///
     /// This is used for indexing [`Compilation::extra_env`].
-    pub script_meta: Option<UnitHash>,
+    pub script_metas: Option<Vec<UnitHash>>,
 }
 
 /// A structure returning the result of a compilation.
@@ -197,14 +197,14 @@ impl<'gctx> Compilation<'gctx> {
     pub fn rustdoc_process(
         &self,
         unit: &Unit,
-        script_meta: Option<UnitHash>,
+        script_metas: Option<&Vec<UnitHash>>,
     ) -> CargoResult<ProcessBuilder> {
         let mut rustdoc = ProcessBuilder::new(&*self.gctx.rustdoc()?);
         if self.gctx.extra_verbose() {
             rustdoc.display_env_vars();
         }
         let cmd = fill_rustc_tool_env(rustdoc, unit);
-        let mut cmd = self.fill_env(cmd, &unit.pkg, script_meta, unit.kind, ToolKind::Rustdoc)?;
+        let mut cmd = self.fill_env(cmd, &unit.pkg, script_metas, unit.kind, ToolKind::Rustdoc)?;
         cmd.retry_with_argfile(true);
         unit.target.edition().cmd_edition_arg(&mut cmd);
 
@@ -248,15 +248,15 @@ impl<'gctx> Compilation<'gctx> {
     /// target platform. This is typically used for `cargo run` and `cargo
     /// test`.
     ///
-    /// `script_meta` is the metadata for the `RunCustomBuild` unit that this
+    /// `script_metas` is the metadata for the `RunCustomBuild` unit that this
     /// unit used for its build script. Use `None` if the package did not have
     /// a build script.
     pub fn target_process<T: AsRef<OsStr>>(
         &self,
         cmd: T,
         kind: CompileKind,
         pkg: &Package,
-        script_meta: Option<UnitHash>,
+        script_metas: Option<&Vec<UnitHash>>,
     ) -> CargoResult<ProcessBuilder> {
         let builder = if let Some((runner, args)) = self.target_runner(kind) {
             let mut builder = ProcessBuilder::new(runner);
@@ -267,7 +267,7 @@ impl<'gctx> Compilation<'gctx> {
             ProcessBuilder::new(cmd)
         };
         let tool_kind = ToolKind::TargetProcess;
-        let mut builder = self.fill_env(builder, pkg, script_meta, kind, tool_kind)?;
+        let mut builder = self.fill_env(builder, pkg, script_metas, kind, tool_kind)?;
 
         if let Some(client) = self.gctx.jobserver_from_env() {
             builder.inherit_jobserver(client);
@@ -285,7 +285,7 @@ impl<'gctx> Compilation<'gctx> {
         &self,
         mut cmd: ProcessBuilder,
         pkg: &Package,
-        script_meta: Option<UnitHash>,
+        script_metas: Option<&Vec<UnitHash>>,
         kind: CompileKind,
         tool_kind: ToolKind,
     ) -> CargoResult<ProcessBuilder> {
@@ -343,10 +343,12 @@ impl<'gctx> Compilation<'gctx> {
         let search_path = paths::join_paths(&search_path, paths::dylib_path_envvar())?;
 
         cmd.env(paths::dylib_path_envvar(), &search_path);
-        if let Some(meta) = script_meta {
-            if let Some(env) = self.extra_env.get(&meta) {
-                for (k, v) in env {
-                    cmd.env(k, v);
+        if let Some(meta_vec) = script_metas {
+            for meta in meta_vec {
+                if let Some(env) = self.extra_env.get(meta) {
+                    for (k, v) in env {
+                        cmd.env(k, v);
+                    }
                 }
             }
         }

src/cargo/core/compiler/custom_build.rs

@@ -1283,10 +1283,12 @@ pub fn build_map(build_runner: &mut BuildRunner<'_, '_>) -> CargoResult<()> {
 
         // If a package has a build script, add itself as something to inspect for linking.
         if !unit.target.is_custom_build() && unit.pkg.has_custom_build() {
-            let script_meta = build_runner
-                .find_build_script_metadata(unit)
+            let script_metas = build_runner
+                .find_build_script_metadatas(unit)
                 .expect("has_custom_build should have RunCustomBuild");
-            add_to_link(&mut ret, unit.pkg.package_id(), script_meta);
+            for script_meta in script_metas {
+                add_to_link(&mut ret, unit.pkg.package_id(), script_meta);
+            }
         }
 
         if unit.mode.is_run_custom_build() {

src/cargo/core/compiler/job_queue/mod.rs

@@ -981,28 +981,30 @@ impl<'gctx> DrainState<'gctx> {
         show_warnings: bool,
     ) -> CargoResult<()> {
         let outputs = build_runner.build_script_outputs.lock().unwrap();
-        let Some(metadata) = build_runner.find_build_script_metadata(unit) else {
+        let Some(metadata_vec) = build_runner.find_build_script_metadatas(unit) else {
             return Ok(());
         };
         let bcx = &mut build_runner.bcx;
-        if let Some(output) = outputs.get(metadata) {
-            if !output.log_messages.is_empty()
-                && (show_warnings
-                    || output
-                        .log_messages
-                        .iter()
-                        .any(|(severity, _)| *severity == Severity::Error))
-            {
-                let msg_with_package =
-                    |msg: &str| format!("{}@{}: {}", unit.pkg.name(), unit.pkg.version(), msg);
-
-                for (severity, message) in output.log_messages.iter() {
-                    match severity {
-                        Severity::Error => {
-                            bcx.gctx.shell().error(msg_with_package(message))?;
-                        }
-                        Severity::Warning => {
-                            bcx.gctx.shell().warn(msg_with_package(message))?;
+        for metadata in metadata_vec {
+            if let Some(output) = outputs.get(metadata) {
+                if !output.log_messages.is_empty()
+                    && (show_warnings
+                        || output
+                            .log_messages
+                            .iter()
+                            .any(|(severity, _)| *severity == Severity::Error))
+                {
+                    let msg_with_package =
+                        |msg: &str| format!("{}@{}: {}", unit.pkg.name(), unit.pkg.version(), msg);
+
+                    for (severity, message) in output.log_messages.iter() {
+                        match severity {
+                            Severity::Error => {
+                                bcx.gctx.shell().error(msg_with_package(message))?;
+                            }
+                            Severity::Warning => {
+                                bcx.gctx.shell().warn(msg_with_package(message))?;
+                            }
                         }
                     }
                 }

src/cargo/core/compiler/mod.rs

@@ -313,7 +313,7 @@ fn rustc(
         .unwrap_or_else(|| build_runner.bcx.gctx.cwd())
         .to_path_buf();
     let fingerprint_dir = build_runner.files().fingerprint_dir(unit);
-    let script_metadata = build_runner.find_build_script_metadata(unit);
+    let script_metadatas = build_runner.find_build_script_metadatas(unit);
     let is_local = unit.is_local();
     let artifact = unit.artifact;
     let sbom_files = build_runner.sbom_output_files(unit)?;
@@ -371,7 +371,7 @@ fn rustc(
                 )?;
                 add_plugin_deps(&mut rustc, &script_outputs, &build_scripts, &root_output)?;
             }
-            add_custom_flags(&mut rustc, &script_outputs, script_metadata)?;
+            add_custom_flags(&mut rustc, &script_outputs, script_metadatas)?;
         }
 
         for output in outputs.iter() {
@@ -920,7 +920,7 @@ fn rustdoc(build_runner: &mut BuildRunner<'_, '_>, unit: &Unit) -> CargoResult<W
     let rustdoc_depinfo_enabled = build_runner.bcx.gctx.cli_unstable().rustdoc_depinfo;
 
     let mut output_options = OutputOptions::new(build_runner, unit);
-    let script_metadata = build_runner.find_build_script_metadata(unit);
+    let script_metadatas = build_runner.find_build_script_metadatas(unit);
     let scrape_outputs = if should_include_scrape_units(build_runner.bcx, unit) {
         Some(
             build_runner
@@ -960,7 +960,7 @@ fn rustdoc(build_runner: &mut BuildRunner<'_, '_>, unit: &Unit) -> CargoResult<W
         add_custom_flags(
             &mut rustdoc,
             &build_script_outputs.lock().unwrap(),
-            script_metadata,
+            script_metadatas,
         )?;
 
         // Add the output of scraped examples to the rustdoc command.
@@ -1686,18 +1686,20 @@ fn build_deps_args(
 fn add_custom_flags(
     cmd: &mut ProcessBuilder,
     build_script_outputs: &BuildScriptOutputs,
-    metadata: Option<UnitHash>,
+    metadata_vec: Option<Vec<UnitHash>>,
 ) -> CargoResult<()> {
-    if let Some(metadata) = metadata {
-        if let Some(output) = build_script_outputs.get(metadata) {
-            for cfg in output.cfgs.iter() {
-                cmd.arg("--cfg").arg(cfg);
-            }
-            for check_cfg in &output.check_cfgs {
-                cmd.arg("--check-cfg").arg(check_cfg);
-            }
-            for (name, value) in output.env.iter() {
-                cmd.env(name, value);
+    if let Some(metadata_vec) = metadata_vec {
+        for metadata in metadata_vec {
+            if let Some(output) = build_script_outputs.get(metadata) {
+                for cfg in output.cfgs.iter() {
+                    cmd.arg("--cfg").arg(cfg);
+                }
+                for check_cfg in &output.check_cfgs {
+                    cmd.arg("--check-cfg").arg(check_cfg);
+                }
+                for (name, value) in output.env.iter() {
+                    cmd.env(name, value);
+                }
             }
         }
     }

src/cargo/core/compiler/output_depinfo.rs

@@ -75,18 +75,20 @@ fn add_deps_for_unit(
     }
 
     // Add rerun-if-changed dependencies
-    if let Some(metadata) = build_runner.find_build_script_metadata(unit) {
-        if let Some(output) = build_runner
-            .build_script_outputs
-            .lock()
-            .unwrap()
-            .get(metadata)
-        {
-            for path in &output.rerun_if_changed {
-                // The paths we have saved from the unit are of arbitrary relativeness and may be
-                // relative to the crate root of the dependency.
-                let path = unit.pkg.root().join(path);
-                deps.insert(path);
+    if let Some(metadata_vec) = build_runner.find_build_script_metadatas(unit) {
+        for metadata in metadata_vec {
+            if let Some(output) = build_runner
+                .build_script_outputs
+                .lock()
+                .unwrap()
+                .get(metadata)
+            {
+                for path in &output.rerun_if_changed {
+                    // The paths we have saved from the unit are of arbitrary relativeness and may be
+                    // relative to the crate root of the dependency.
+                    let path = unit.pkg.root().join(path);
+                    deps.insert(path);
+                }
             }
         }
     }