Move toolchain install handling out of CLI

Author: tuguzT

Cargo.lock

@@ -1,14 +1,15 @@
+//! `cargo gpu build`, analogous to `cargo build`
+
 #![allow(clippy::shadow_reuse, reason = "let's not be silly")]
 #![allow(clippy::unwrap_used, reason = "this is basically a test")]
-//! `cargo gpu build`, analogous to `cargo build`
 
-use crate::install::Install;
-use crate::linkage::Linkage;
-use crate::lockfile::LockfileMismatchHandler;
+use std::{io::Write as _, path::PathBuf};
+
 use anyhow::Context as _;
+use rustc_codegen_spirv_cache::user_output;
 use spirv_builder::{CompileResult, ModuleResult, SpirvBuilder};
-use std::io::Write as _;
-use std::path::PathBuf;
+
+use crate::{install::Install, linkage::Linkage, lockfile::LockfileMismatchHandler};
 
 /// Args for just a build
 #[derive(clap::Parser, Debug, Clone, serde::Deserialize, serde::Serialize)]
@@ -102,10 +103,11 @@ impl Build {
                 .context("unreachable")??;
             std::thread::park();
         } else {
-            crate::user_output!(
+            user_output!(
+                std::io::stdout(),
                 "Compiling shaders at {}...\n",
                 self.install.shader_crate.display()
-            );
+            )?;
             let result = self.build.spirv_builder.build()?;
             self.parse_compilation_result(&result)?;
         }

crates/cargo-gpu/src/build.rs

@@ -1,7 +1,9 @@
 //! Convenience function for internal use. Dumps all the CLI usage instructions. Useful for
 //! updating the README.
 
-use crate::{user_output, Cli};
+use rustc_codegen_spirv_cache::user_output;
+
+use crate::Cli;
 
 /// main dump usage function
 pub fn dump_full_usage_for_readme() -> anyhow::Result<()> {
@@ -12,7 +14,8 @@ pub fn dump_full_usage_for_readme() -> anyhow::Result<()> {
     command.build();
 
     write_help(&mut buffer, &mut command, 0)?;
-    user_output!("{}", String::from_utf8(buffer)?);
+    let message = String::from_utf8(buffer)?;
+    user_output!(std::io::stdout(), "{message}")?;
 
     Ok(())
 }

crates/cargo-gpu/src/dump_usage.rs

@@ -10,6 +10,7 @@ use rustc_codegen_spirv_cache::{
         SpirvSource,
     },
     target_specs::update_target_specs_files,
+    toolchain, user_output,
 };
 use spirv_builder::SpirvBuilder;
 
@@ -273,7 +274,7 @@ package = "rustc_codegen_spirv"
             .context("writing target spec files")?;
 
         log::debug!("ensure_toolchain_and_components_exist");
-        crate::install_toolchain::ensure_toolchain_and_components_exist(
+        toolchain::ensure_toolchain_and_components_exist(
             &toolchain_channel,
             self.auto_install_rust_toolchain,
         )
@@ -287,7 +288,10 @@ package = "rustc_codegen_spirv"
                     .context("remove Cargo.lock")?;
             }
 
-            crate::user_output!("Compiling `rustc_codegen_spirv` from source {}\n", source);
+            user_output!(
+                std::io::stdout(),
+                "Compiling `rustc_codegen_spirv` from source {source}\n"
+            )?;
             let mut cargo = spirv_builder::cargo_cmd::CargoCmd::new();
             cargo
                 .current_dir(&install_dir)

crates/cargo-gpu/src/install.rs

@@ -58,7 +58,6 @@ mod build;
 mod config;
 mod dump_usage;
 mod install;
-mod install_toolchain;
 mod linkage;
 mod lockfile;
 mod metadata;
@@ -68,30 +67,6 @@ mod test;
 pub use install::*;
 pub use spirv_builder;
 
-/// Central function to write to the user.
-#[macro_export]
-macro_rules! user_output {
-    ($($args: tt)*) => {
-        #[allow(
-            clippy::allow_attributes,
-            clippy::useless_attribute,
-            unused_imports,
-            reason = "`std::io::Write` is only sometimes called??"
-        )]
-        use std::io::Write as _;
-
-        #[expect(
-            clippy::non_ascii_literal,
-            reason = "CRAB GOOD. CRAB IMPORTANT."
-        )]
-        {
-            print!("🦀 ");
-        }
-        print!($($args)*);
-        std::io::stdout().flush().unwrap();
-   }
-}
-
 /// All of the available subcommands for `cargo gpu`
 #[derive(clap::Subcommand)]
 #[non_exhaustive]

crates/cargo-gpu/src/lib.rs

@@ -3,6 +3,7 @@
 //! present. This module takes care of warning the user and potentially downgrading the lockfile.
 
 use anyhow::Context as _;
+use rustc_codegen_spirv_cache::user_output;
 use semver::Version;
 use spirv_builder::query_rustc_version;
 use std::io::Write as _;
@@ -188,7 +189,7 @@ impl LockfileMismatchHandler {
         is_force_overwrite_lockfiles_v4_to_v3: bool,
     ) -> anyhow::Result<()> {
         if !is_force_overwrite_lockfiles_v4_to_v3 {
-            Self::exit_with_v3v4_hack_suggestion();
+            Self::exit_with_v3v4_hack_suggestion()?;
         }
 
         Self::replace_cargo_lock_manifest_version(offending_cargo_lock, "4", "3")
@@ -240,9 +241,9 @@ impl LockfileMismatchHandler {
 
     /// Exit and give the user advice on how to deal with the infamous v3/v4 Cargo lockfile version
     /// problem.
-    #[expect(clippy::non_ascii_literal, reason = "It's CLI output")]
-    fn exit_with_v3v4_hack_suggestion() {
-        crate::user_output!(
+    fn exit_with_v3v4_hack_suggestion() -> anyhow::Result<()> {
+        user_output!(
+            std::io::stdout(),
             "Conflicting `Cargo.lock` versions detected ⚠️\n\
             Because `cargo gpu` uses a dedicated Rust toolchain for compiling shaders\n\
             it's possible that the `Cargo.lock` manifest version of the shader crate\n\
@@ -259,7 +260,7 @@ impl LockfileMismatchHandler {
             \n\
             See `cargo gpu build --help` for more information.\n\
             "
-        );
+        )?;
         std::process::exit(1);
     }
 }

crates/cargo-gpu/src/lockfile.rs

@@ -14,6 +14,7 @@ anyhow.workspace = true
 log.workspace = true
 directories.workspace = true
 cargo_metadata.workspace = true
+crossterm.workspace = true
 
 [dev-dependencies]
 test-log.workspace = true

crates/rustc_codegen_spirv-cache/Cargo.toml

@@ -17,3 +17,24 @@
 pub mod cache;
 pub mod spirv_source;
 pub mod target_specs;
+pub mod toolchain;
+
+/// Writes formatted user output into a [writer](std::io::Write).
+#[macro_export]
+macro_rules! user_output {
+    ($dst:expr, $($args:tt)*) => {{
+        #[allow(
+            clippy::allow_attributes,
+            clippy::useless_attribute,
+            unused_imports,
+            reason = "`std::io::Write` is only sometimes called??"
+        )]
+        use ::std::io::Write as _;
+
+        let mut writer = $dst;
+        #[expect(clippy::non_ascii_literal, reason = "CRAB GOOD. CRAB IMPORTANT.")]
+        ::std::write!(writer, "🦀 ")
+            .and_then(|()| ::std::write!(writer, $($args)*))
+            .and_then(|()| ::std::io::Write::flush(&mut writer))
+    }};
+}

crates/rustc_codegen_spirv-cache/src/lib.rs

@@ -3,14 +3,13 @@
 use anyhow::Context as _;
 use crossterm::tty::IsTty as _;
 
-use crate::user_output;
-
 /// Use `rustup` to install the toolchain and components, if not already installed.
 ///
 /// Pretty much runs:
 ///
 /// * rustup toolchain add nightly-2024-04-24
 /// * rustup component add --toolchain nightly-2024-04-24 rust-src rustc-dev llvm-tools
+#[inline]
 pub fn ensure_toolchain_and_components_exist(
     channel: &str,
     skip_toolchain_install_consent: bool,
@@ -36,7 +35,7 @@ pub fn ensure_toolchain_and_components_exist(
             format!("Install {message}").as_ref(),
             skip_toolchain_install_consent,
         )?;
-        crate::user_output!("Installing {message}\n");
+        crate::user_output!(std::io::stdout(), "Installing {message}\n")?;
 
         let output_toolchain_add = std::process::Command::new("rustup")
             .args(["toolchain", "add"])
@@ -79,7 +78,7 @@ pub fn ensure_toolchain_and_components_exist(
             format!("Install {message}").as_ref(),
             skip_toolchain_install_consent,
         )?;
-        crate::user_output!("Installing {message}\n");
+        crate::user_output!(std::io::stdout(), "Installing {message}\n")?;
 
         let output_component_add = std::process::Command::new("rustup")
             .args(["component", "add", "--toolchain"])
@@ -108,15 +107,18 @@ fn get_consent_for_toolchain_install(
     }
 
     if !std::io::stdout().is_tty() {
-        user_output!("No TTY detected so can't ask for consent to install Rust toolchain.");
+        crate::user_output!(
+            std::io::stdout(),
+            "No TTY detected so can't ask for consent to install Rust toolchain."
+        )?;
         log::error!("Attempted to ask for consent when there's no TTY");
         #[expect(clippy::exit, reason = "can't ask for user consent if there's no TTY")]
         std::process::exit(1);
     }
 
     log::debug!("asking for consent to install the required toolchain");
     crossterm::terminal::enable_raw_mode().context("enabling raw mode")?;
-    crate::user_output!("{prompt} [y/n]: ");
+    crate::user_output!(std::io::stdout(), "{prompt} [y/n]: ")?;
     let mut input = crossterm::event::read().context("reading crossterm event")?;
 
     if let crossterm::event::Event::Key(crossterm::event::KeyEvent {
@@ -138,7 +140,7 @@ fn get_consent_for_toolchain_install(
     {
         Ok(())
     } else {
-        crate::user_output!("Exiting...\n");
+        crate::user_output!(std::io::stdout(), "Exiting...\n")?;
         #[expect(clippy::exit, reason = "user requested abort")]
         std::process::exit(0);
     }