Make cargo test work for bootstrap self test

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

@@ -22,13 +22,7 @@ fn configure(cmd: &str, host: &[&str], target: &[&str]) -> Config {
 }
 
 fn configure_with_args(cmd: &[&str], host: &[&str], target: &[&str]) -> Config {
-    TestCtx::new()
-        .config(cmd[0])
-        .args(&cmd[1..])
-        .hosts(host)
-        .targets(target)
-        .args(&["--build", TEST_TRIPLE_1])
-        .create_config()
+    TestCtx::new().config(cmd[0]).args(&cmd[1..]).hosts(host).targets(target).create_config()
 }
 
 fn first<A, B>(v: Vec<(A, B)>) -> Vec<A> {
@@ -218,25 +212,25 @@ 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 {
     use pretty_assertions::assert_eq;
 
     use super::{Config, TEST_TRIPLE_1, TEST_TRIPLE_2, TEST_TRIPLE_3, first, run_build};
     use crate::Flags;
+    use crate::core::builder::tests::host_target;
     use crate::core::builder::*;
 
     fn configure(host: &[&str], target: &[&str]) -> Config {
@@ -245,11 +239,11 @@ mod dist {
 
     #[test]
     fn llvm_out_behaviour() {
-        let mut config = configure(&[TEST_TRIPLE_1], &[TEST_TRIPLE_2]);
+        let mut config = configure(&[], &[TEST_TRIPLE_2]);
         config.llvm_from_ci = true;
         let build = Build::new(config.clone());
 
-        let target = TargetSelection::from_user(TEST_TRIPLE_1);
+        let target = TargetSelection::from_user(&host_target());
         assert!(build.llvm_out(target).ends_with("ci-llvm"));
         let target = TargetSelection::from_user(TEST_TRIPLE_2);
         assert!(build.llvm_out(target).ends_with("llvm"));
@@ -314,7 +308,7 @@ mod sysroot_target_dirs {
 /// cg_gcc tests instead.
 #[test]
 fn test_test_compiler() {
-    let config = configure_with_args(&["test", "compiler"], &[TEST_TRIPLE_1], &[TEST_TRIPLE_1]);
+    let config = configure_with_args(&["test", "compiler"], &[&host_target()], &[TEST_TRIPLE_1]);
     let cache = run_build(&config.paths.clone(), config);
 
     let compiler = cache.contains::<test::CrateLibrustc>();
@@ -347,7 +341,7 @@ fn test_test_coverage() {
         // Print each test case so that if one fails, the most recently printed
         // case is the one that failed.
         println!("Testing case: {cmd:?}");
-        let config = configure_with_args(cmd, &[TEST_TRIPLE_1], &[TEST_TRIPLE_1]);
+        let config = configure_with_args(cmd, &[], &[TEST_TRIPLE_1]);
         let mut cache = run_build(&config.paths.clone(), config);
 
         let modes =
@@ -359,14 +353,7 @@ 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

@@ -414,14 +414,28 @@ impl Config {
         // Set config values based on flags.
         let mut exec_ctx = ExecutionContext::new(flags_verbose, flags_cmd.fail_fast());
         exec_ctx.set_dry_run(if flags_dry_run { DryRun::UserSelected } else { DryRun::Disabled });
-        let mut src = {
+
+        let default_src_dir = {
             let manifest_dir = PathBuf::from(env!("CARGO_MANIFEST_DIR"));
             // Undo `src/bootstrap`
             manifest_dir.parent().unwrap().parent().unwrap().to_owned()
         };
+        let src = if let Some(s) = compute_src_directory(flags_src, &exec_ctx) {
+            s
+        } else {
+            default_src_dir.clone()
+        };
 
-        if let Some(src_) = compute_src_directory(flags_src, &exec_ctx) {
-            src = src_;
+        #[cfg(test)]
+        {
+            if let Some(config_path) = flags_config.as_ref() {
+                assert!(
+                    !config_path.starts_with(&src),
+                    "Path {config_path:?} should not be inside or equal to src dir {src:?}"
+                );
+            } else {
+                panic!("During test the config should be explicitly added");
+            }
         }
 
         // Now load the TOML config, as soon as possible
@@ -630,19 +644,13 @@ 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 = flags_build_dir.or_else(|| build_build_dir.map(PathBuf::from));
+        let out = if cfg!(test) {
+            out.expect("--build-dir has to be specified in tests")
+        } else {
+            out.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.
@@ -653,6 +661,10 @@ impl Config {
             out
         };
 
+        let default_stage0_rustc_path = |dir: &Path| {
+            dir.join(host_target).join("stage0").join("bin").join(exe("rustc", host_target))
+        };
+
         if cfg!(test) {
             // When configuring bootstrap for tests, make sure to set the rustc and Cargo to the
             // same ones used to call the tests (if custom ones are not defined in the toml). If we
@@ -661,6 +673,22 @@ impl Config {
             // Cargo in their bootstrap.toml.
             build_rustc = build_rustc.take().or(std::env::var_os("RUSTC").map(|p| p.into()));
             build_cargo = build_cargo.take().or(std::env::var_os("CARGO").map(|p| p.into()));
+
+            // If we are running only `cargo test` (and not `x test bootstrap`), which is useful
+            // e.g. for debugging bootstrap itself, then we won't have RUSTC and CARGO set to the
+            // proper paths.
+            // We thus "guess" that the build directory is located at <src>/build, and try to load
+            // rustc and cargo from there
+            let is_test_outside_x = std::env::var("CARGO_TARGET_DIR").is_err();
+            if is_test_outside_x && build_rustc.is_none() {
+                let stage0_rustc = default_stage0_rustc_path(&default_src_dir.join("build"));
+                assert!(
+                    stage0_rustc.exists(),
+                    "Trying to run cargo test without having a stage0 rustc available in {}",
+                    stage0_rustc.display()
+                );
+                build_rustc = Some(stage0_rustc);
+            }
         }
 
         if !flags_skip_stage0_validation {
@@ -694,7 +722,7 @@ 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))
+            default_stage0_rustc_path(&out)
         });
 
         let initial_sysroot = t!(PathBuf::from_str(
@@ -1534,11 +1562,11 @@ impl Config {
                                 println!("WARNING: CI rustc has some fields that are no longer supported in bootstrap; download-rustc will be disabled.");
                                 println!("HELP: Consider rebasing to a newer commit if available.");
                                 return None;
-                            },
+                            }
                             Err(e) => {
                                 eprintln!("ERROR: Failed to parse CI rustc bootstrap.toml: {e}");
                                 exit!(2);
-                            },
+                            }
                         };
 
                         let current_config_toml = Self::get_toml(config_path).unwrap();