Decouple cache dir implementation from tests

Author: tuguzT

Cargo.lock

@@ -1,5 +1,6 @@
 [workspace]
 members = [
+	"crates/rustc_codegen_spirv-cache",
 	"crates/cargo-gpu-cache",
 	"crates/cargo-gpu",
 	"crates/xtask",

Cargo.toml

@@ -8,12 +8,12 @@ keywords.workspace = true
 license.workspace = true
 
 [dependencies]
+rustc_codegen_spirv-cache = { path = "../rustc_codegen_spirv-cache", default-features = false }
 cargo_metadata.workspace = true
 anyhow.workspace = true
 spirv-builder.workspace = true
 legacy_target_specs.workspace = true
 clap = { workspace = true, optional = true }
-directories.workspace = true
 log.workspace = true
 relative-path.workspace = true
 serde.workspace = true
@@ -24,6 +24,7 @@ dunce.workspace = true
 
 [dev-dependencies]
 test-log.workspace = true
+tempfile.workspace = true
 cargo_metadata = { workspace = true, features = ["builder"] }
 cargo-util-schemas.workspace = true
 

crates/cargo-gpu-cache/Cargo.toml

@@ -110,7 +110,7 @@ impl Build {
         crate::user_output!(
             "Compiling shaders at {}...\n",
             self.install.shader_crate.display()
-        );
+        )?;
         let result = self.build.spirv_builder.build()?;
         self.parse_compilation_result(&result)?;
         Ok(())

crates/cargo-gpu-cache/src/build.rs

@@ -14,7 +14,9 @@ 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!("{message}")?;
 
     Ok(())
 }

crates/cargo-gpu-cache/src/dump_usage.rs

@@ -1,13 +1,16 @@
 //! Install a dedicated per-shader crate that has the `rust-gpu` compiler in it.
 
+use std::path::{Path, PathBuf};
+
+use anyhow::Context as _;
+use rustc_codegen_spirv_cache::cache_dir;
+use spirv_builder::SpirvBuilder;
+
+use crate::spirv_source::SpirvSource;
 use crate::spirv_source::{
     get_channel_from_rustc_codegen_spirv_build_script, query_metadata, FindPackage as _,
 };
 use crate::target_specs::update_target_specs_files;
-use crate::{cache_dir, spirv_source::SpirvSource};
-use anyhow::Context as _;
-use spirv_builder::SpirvBuilder;
-use std::path::{Path, PathBuf};
 
 /// Represents a functional backend installation, whether it was cached or just installed.
 #[derive(Clone, Debug, Default)]
@@ -284,7 +287,7 @@ package = "rustc_codegen_spirv"
                     .context("remove Cargo.lock")?;
             }
 
-            crate::user_output!("Compiling `rustc_codegen_spirv` from source {}\n", source);
+            crate::user_output!("Compiling `rustc_codegen_spirv` from source {}\n", source)?;
             let mut cargo = spirv_builder::cargo_cmd::CargoCmd::new();
             cargo
                 .current_dir(&install_dir)

crates/cargo-gpu-cache/src/install.rs

@@ -36,7 +36,7 @@ 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!("Installing {message}\n")?;
 
         let output_toolchain_add = std::process::Command::new("rustup")
             .args(["toolchain", "add"])
@@ -79,7 +79,7 @@ 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!("Installing {message}\n")?;
 
         let output_component_add = std::process::Command::new("rustup")
             .args(["component", "add", "--toolchain"])
@@ -108,15 +108,15 @@ 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.");
+        user_output!("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!("{prompt} [y/n]: ")?;
     let mut input = crossterm::event::read().context("reading crossterm event")?;
 
     if let crossterm::event::Event::Key(crossterm::event::KeyEvent {
@@ -138,7 +138,7 @@ fn get_consent_for_toolchain_install(
     {
         Ok(())
     } else {
-        crate::user_output!("Exiting...\n");
+        crate::user_output!("Exiting...\n")?;
         #[expect(clippy::exit, reason = "user requested abort")]
         std::process::exit(0);
     }

crates/cargo-gpu-cache/src/install_toolchain.rs

@@ -7,27 +7,14 @@
 //!
 //! # How it works
 //!
-//! This library primarily manages installations of `rustc_codegen_spirv`, the
-//! codegen backend of rust-gpu to generate SPIR-V shader binaries. The codegen
-//! backend builds on internal, ever-changing interfaces of rustc, which requires
-//! fixing a version of rust-gpu to a specific version of the rustc compiler.
-//! Usually, this would require you to fix your entire project to that specific
-//! toolchain, but this project loosens that requirement by managing installations
-//! of `rustc_codegen_spirv` and their associated toolchains for you.
+//! This library manages installations of `rustc_codegen_spirv`
+//! using rust-gpu's [`rustc_codegen_spirv-cache`](rustc_codegen_spirv_cache) crate.
 //!
-//! We continue to use rust-gpu's `spirv_builder` crate to pass the many additional
-//! parameters required to configure rustc and our codegen backend, but provide you
-//! with a toolchain agnostic version that you may use from stable rustc.
+//! Then we continue to use rust-gpu's [`spirv-builder`](spirv_builder) crate
+//! to pass the many additional parameters required to configure rustc and our codegen backend,
+//! but provide you with a toolchain agnostic version that you may use from stable rustc.
 //! And a `cargo gpu` command line utility to simplify shader building even more.
 //!
-//! ## Where the binaries are
-//!
-//! We store our prebuilt `rustc_spirv_builder` binaries in the default cache
-//! directory of your OS:
-//! * Windows: `C:/users/<user>/AppData/Local/rust-gpu`
-//! * Mac: `~/Library/Caches/rust-gpu`
-//! * Linux: `~/.cache/rust-gpu`
-//!
 //! ## How we build the backend
 //!
 //! * retrieve the version of rust-gpu you want to use based on the version of the
@@ -50,8 +37,6 @@
 //! conduct other post-processing, like converting the `spv` files into `wgsl` files,
 //! for example.
 
-use anyhow::Context as _;
-
 use build::Build;
 use show::Show;
 
@@ -74,28 +59,30 @@ mod test;
 pub use install::*;
 pub use spirv_builder;
 
-/// Central function to write to the user.
+/// Writes formatted user output into a [writer](std::io::Write).
 #[macro_export]
-macro_rules! user_output {
-    ($($args: tt)*) => {
+macro_rules! write_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 _;
+        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))
+    }};
+}
 
-        #[expect(
-            clippy::non_ascii_literal,
-            reason = "CRAB GOOD. CRAB IMPORTANT."
-        )]
-        {
-            print!("🦀 ");
-        }
-        print!($($args)*);
-        std::io::stdout().flush().unwrap();
-   }
+/// Central function to write to the user.
+#[macro_export]
+macro_rules! user_output {
+    ($($args: tt)*) => { $crate::write_user_output!(::std::io::stdout(), $($args)*) };
 }
 
 /// All of the available subcommands for `cargo gpu`
@@ -176,26 +163,6 @@ pub struct Cli {
     pub command: Command,
 }
 
-/// The central cache directory of cargo gpu
-///
-/// # Errors
-/// may fail if we can't find the user home directory
-#[inline]
-pub fn cache_dir() -> anyhow::Result<std::path::PathBuf> {
-    let dir = directories::BaseDirs::new()
-        .with_context(|| "could not find the user home directory")?
-        .cache_dir()
-        .join("rust-gpu");
-
-    Ok(if cfg!(test) {
-        let thread_id = std::thread::current().id();
-        let id = format!("{thread_id:?}").replace('(', "-").replace(')', "");
-        dir.join("tests").join(id)
-    } else {
-        dir
-    })
-}
-
 /// Returns a string suitable to use as a directory.
 ///
 /// Created from the spirv-builder source dep and the rustc channel.

crates/cargo-gpu-cache/src/lib.rs

@@ -238,9 +238,9 @@ impl LockfileMismatchHandler {
         Ok(())
     }
 
-    /// 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")]
+    /// Exit and give the user advice on how to deal with the infamous
+    /// v3/v4 Cargo lockfile version problem.
+    #[expect(clippy::unwrap_used, reason = "It's CLI output")]
     fn exit_with_v3v4_hack_suggestion() {
         crate::user_output!(
             "Conflicting `Cargo.lock` versions detected ⚠️\n\
@@ -259,7 +259,8 @@ impl LockfileMismatchHandler {
             \n\
             See `cargo gpu build --help` for more information.\n\
             "
-        );
+        )
+        .unwrap();
         std::process::exit(1);
     }
 }

crates/cargo-gpu-cache/src/lockfile.rs

@@ -1,11 +1,14 @@
 //! Display various information about `cargo gpu`, eg its cache directory.
 
-use crate::cache_dir;
-use crate::spirv_source::{query_metadata, SpirvSource};
-use crate::target_specs::update_target_specs_files;
+use std::{fs, path::Path};
+
 use anyhow::bail;
-use std::fs;
-use std::path::Path;
+use rustc_codegen_spirv_cache::cache_dir;
+
+use crate::{
+    spirv_source::{query_metadata, SpirvSource},
+    target_specs::update_target_specs_files,
+};
 
 /// Show the computed source of the spirv-std dependency.
 #[derive(Clone, Debug)]