Make cargo test work for bootstrap self test

src/bootstrap/src/core/builder/tests.rs

@@ -218,18 +218,17 @@ fn prepare_rustc_checkout(ctx: &mut GitCtx) {
 
 /// Parses a Config directory from `path`, with the given value of `download_rustc`.
 fn parse_config_download_rustc_at(path: &Path, download_rustc: &str, ci: bool) -> Config {
-    Config::parse_inner(
-        Flags::parse(&[
-            "build".to_owned(),
-            "--dry-run".to_owned(),
-            "--ci".to_owned(),
-            if ci { "true" } else { "false" }.to_owned(),
-            format!("--set=rust.download-rustc='{download_rustc}'"),
-            "--src".to_owned(),
-            path.to_str().unwrap().to_owned(),
-        ]),
-        |&_| Ok(Default::default()),
-    )
+    TestCtx::new()
+        .config("build")
+        .args(&[
+            "--ci",
+            if ci { "true" } else { "false" },
+            format!("--set=rust.download-rustc='{download_rustc}'").as_str(),
+            "--src",
+            path.to_str().unwrap(),
+        ])
+        .no_override_download_ci_llvm()
+        .create_config()
 }
 
 mod dist {
@@ -359,14 +358,7 @@ fn test_test_coverage() {
 #[test]
 fn test_prebuilt_llvm_config_path_resolution() {
     fn configure(config: &str) -> Config {
-        Config::parse_inner(
-            Flags::parse(&[
-                "build".to_string(),
-                "--dry-run".to_string(),
-                "--config=/does/not/exist".to_string(),
-            ]),
-            |&_| toml::from_str(&config),
-        )
+        TestCtx::new().config("build").with_default_toml_config(config).create_config()
     }
 
     // Removes Windows disk prefix if present

src/bootstrap/src/core/config/config.rs

@@ -630,19 +630,13 @@ impl Config {
         let llvm_assertions = llvm_assertions.unwrap_or(false);
         let mut target_config = HashMap::new();
         let mut channel = "dev".to_string();
-        let out = flags_build_dir.or(build_build_dir.map(PathBuf::from)).unwrap_or_else(|| {
-            if cfg!(test) {
-                // Use the build directory of the original x.py invocation, so that we can set `initial_rustc` properly.
-                Path::new(
-                    &env::var_os("CARGO_TARGET_DIR").expect("cargo test directly is not supported"),
-                )
-                .parent()
-                .unwrap()
-                .to_path_buf()
-            } else {
-                PathBuf::from("build")
-            }
-        });
+        let out = if cfg!(test) {
+            test_build_dir()
+        } else {
+            flags_build_dir
+                .or_else(|| build_build_dir.map(PathBuf::from))
+                .unwrap_or_else(|| PathBuf::from("build"))
+        };
 
         // NOTE: Bootstrap spawns various commands with different working directories.
         // To avoid writing to random places on the file system, `config.out` needs to be an absolute path.
@@ -694,7 +688,9 @@ impl Config {
 
         let initial_rustc = build_rustc.unwrap_or_else(|| {
             download_beta_toolchain(&dwn_ctx, &out);
-            out.join(host_target).join("stage0").join("bin").join(exe("rustc", host_target))
+            let target = if cfg!(test) { get_host_target() } else { host_target };
+
+            out.join(target).join("stage0").join("bin").join(exe("rustc", host_target))
         });
 
         let initial_sysroot = t!(PathBuf::from_str(
@@ -2484,3 +2480,15 @@ fn find_correct_section_for_field(field_name: &str) -> Vec<WouldBeValidFor> {
         })
         .collect()
 }
+
+fn test_build_dir() -> PathBuf {
+    env::var_os("CARGO_TARGET_DIR")
+        .map(|value| Path::new(&value).parent().unwrap().to_path_buf())
+        .unwrap_or_else(|| {
+            let base = option_env!("CARGO_MANIFEST_DIR")
+                .map(PathBuf::from)
+                .unwrap_or_else(|| std::env::current_dir().expect("failed to get current dir"));
+
+            base.ancestors().nth(2).unwrap_or_else(|| Path::new(".")).join("build")
+        })
+}