Implement new sdist feature to download rust toolchain

src/build_context.rs

@@ -8,7 +8,7 @@ use crate::module_writer::{
 };
 use crate::project_layout::ProjectLayout;
 use crate::python_interpreter::InterpreterKind;
-use crate::source_distribution::source_distribution;
+use crate::source_distribution::{download_and_execute_rustup, source_distribution};
 use crate::target::{Arch, Os};
 use crate::{
     compile, pyproject_toml::Format, BuildArtifact, Metadata23, ModuleWriter, PyProjectToml,
@@ -273,6 +273,22 @@ impl BuildContext {
                 let sdist_path =
                     source_distribution(self, pyproject, self.excludes(Format::Sdist)?)
                         .context("Failed to build source distribution")?;
+                if self.require_rust_toolchain() {
+                    let mut target_path = sdist_path.clone().to_path_buf();
+                    target_path.pop();
+                    target_path.pop();
+                    target_path.push("bin");
+
+                    fs::create_dir_all(&target_path)
+                        .context("Fail to create directory for installing rust toolchain")?;
+
+                    let target_path_str = target_path
+                        .to_str()
+                        .context("Fail to construct target path for installing rust toolchain")?;
+
+                    download_and_execute_rustup(target_path_str, target_path_str)
+                        .context("Failed to download rust toolchain")?;
+                }
                 Ok(Some((sdist_path, "source".to_string())))
             }
             None => Ok(None),
@@ -1132,6 +1148,19 @@ impl BuildContext {
         }
         Ok(wheels)
     }
+    /// Check if user requires to install rust toolchain
+    ///
+    /// Loop over `build-system.requires` defined in pyproject.toml and see if `rust-toolchain` is provided
+    pub fn require_rust_toolchain(&self) -> bool {
+        match &self.pyproject_toml {
+            Some(pyproject_toml) => pyproject_toml
+                .build_system
+                .requires
+                .iter()
+                .any(|req| req.name.as_ref() == "rust-toolchain"),
+            None => false,
+        }
+    }
 }
 
 /// Calculate the sha256 of a file

src/source_distribution.rs

@@ -1,5 +1,6 @@
 use crate::module_writer::{add_data, ModuleWriter};
 use crate::pyproject_toml::SdistGenerator;
+use crate::upload::http_agent;
 use crate::{pyproject_toml::Format, BuildContext, PyProjectToml, SDistWriter};
 use anyhow::{bail, Context, Result};
 use cargo_metadata::{Metadata, MetadataCommand, PackageId};
@@ -8,9 +9,11 @@ use ignore::overrides::Override;
 use normpath::PathExt as _;
 use path_slash::PathExt as _;
 use std::collections::HashMap;
+use std::io::copy;
 use std::path::{Path, PathBuf};
 use std::process::Command;
 use std::str;
+use tempfile::NamedTempFile;
 use tracing::debug;
 
 /// Path dependency information.
@@ -735,3 +738,36 @@ where
         None
     }
 }
+
+/// Downloads the rustup installer script and executes it to install rustup
+///
+/// Inspired by https://github.com/chriskuehl/rustenv
+pub fn download_and_execute_rustup(rustup_home: &str, cargo_home: &str) -> Result<()> {
+    let mut tf = NamedTempFile::new()?;
+    let agent = http_agent()?;
+    let response = agent.get("https://sh.rustup.rs").call()?.into_string()?;
+
+    copy(&mut response.as_bytes(), &mut tf)?;
+
+    #[cfg(unix)]
+    {
+        Command::new("sh")
+            .arg(tf.path())
+            .arg("-y")
+            .arg("--no-modify-path")
+            .env("RUSTUP_HOME", rustup_home)
+            .env("CARGO_HOME", cargo_home)
+            .status()?;
+    }
+
+    #[cfg(windows)]
+    {
+        Command::new("cmd")
+            .args(&["/C", tf.path(), "-y", "--no-modify-path"])
+            .env("RUSTUP_HOME", rustup_home)
+            .env("CARGO_HOME", cargo_home)
+            .status()?;
+    }
+
+    Ok(())
+}

src/upload.rs

@@ -382,7 +382,7 @@ fn http_agent() -> Result<ureq::Agent, UploadError> {
 
 #[cfg(feature = "rustls")]
 #[allow(clippy::result_large_err)]
-fn http_agent() -> Result<ureq::Agent, UploadError> {
+pub fn http_agent() -> Result<ureq::Agent, UploadError> {
     use std::sync::Arc;
 
     let builder = ureq::builder().try_proxy_from_env(true);