Auto merge of #110478 - jyn514:stage1-fulldeps, r=albertlarsan68

Support `x test --stage 1 ui-fulldeps`

`@Nilstrieb` had an excellent idea the other day: the same way that rustdoc is able to load `rustc_driver` from the sysroot, ui-fulldeps tests should also be able to load it from the sysroot. That allows us to run fulldeps tests with stage1, without having to fully rebuild the compiler twice. It does unfortunately have the downside that we're building the tests with the *bootstrap* compiler, not the in-tree sources, but since most of the fulldeps tests are for the *API* of the compiler, that seems ok.

I think it's possible to extend this to `run-make-fulldeps`, but I've run out of energy for tonight.

- Move `plugin` tests into a subdirectory.

  Plugins are loaded at runtime with `dlopen` and so require the ABI of the running compile to match the ABI of the compiler linked with `rustc_driver`. As a result they can't be supported in stage 1 and have to use `// ignore-stage1`.

- Remove `ignore-stage1` from most non-plugin tests

- Ignore diagnostic tests in stage 1. Even though this requires a stage 2 build to load rustc_driver, it's primarily testing the error message that the *running* compiler emits when the diagnostic struct is malformed.

- Pass `-Zforce-unstable-if-unmarked` in stage1, not just stage2. That allows running `hash-stable-is-unstable` in stage1, since it now suggests adding `rustc_private` to enable loading the crates.

- Add libLLVM.so to the stage0 target sysroot, to allow fulldeps tests that act as custom drivers to load it at runtime.

- Pass `--sysroot stage0-sysroot` in compiletest so that we use the correct version of std.

- Move a few lint tests from ui-fulldeps to ui

  These had an `aux-build:lint-group-plugin-test.rs` that they never actually loaded with `feature(plugin)` nor tested. I removed the unused aux-build and they pass fine with stage 1.

Fixes https://github.com/rust-lang/rust/issues/75905.

4 files changed, 36 insertions, 7 deletions

diff --git a/src/bootstrap/bin/rustc.rs b/src/bootstrap/bin/rustc.rs
index 040fec3615b..dd86634b47c 100644
--- a/src/bootstrap/bin/rustc.rs
+++ b/src/bootstrap/bin/rustc.rs
@@ -150,7 +150,7 @@ fn main() {
     // allow the `rustc_private` feature to link to other unstable crates
     // also in the sysroot. We also do this for host crates, since those
     // may be proc macros, in which case we might ship them.
-    if env::var_os("RUSTC_FORCE_UNSTABLE").is_some() && (stage != "0" || target.is_some()) {
+    if env::var_os("RUSTC_FORCE_UNSTABLE").is_some() {
         cmd.arg("-Z").arg("force-unstable-if-unmarked");
     }
 
diff --git a/src/bootstrap/builder.rs b/src/bootstrap/builder.rs
index 4977ce22724..9666874d0fe 100644
--- a/src/bootstrap/builder.rs
+++ b/src/bootstrap/builder.rs
@@ -1008,9 +1008,24 @@ impl<'a> Builder<'a> {
                 // Avoid deleting the rustlib/ directory we just copied
                 // (in `impl Step for Sysroot`).
                 if !builder.download_rustc() {
+                    builder.verbose(&format!(
+                        "Removing sysroot {} to avoid caching bugs",
+                        sysroot.display()
+                    ));
                     let _ = fs::remove_dir_all(&sysroot);
                     t!(fs::create_dir_all(&sysroot));
                 }
+
+                if self.compiler.stage == 0 {
+                    // The stage 0 compiler for the build triple is always pre-built.
+                    // Ensure that `libLLVM.so` ends up in the target libdir, so that ui-fulldeps tests can use it when run.
+                    dist::maybe_install_llvm_target(
+                        builder,
+                        self.compiler.host,
+                        &builder.sysroot(self.compiler),
+                    );
+                }
+
                 INTERNER.intern_path(sysroot)
             }
         }
diff --git a/src/bootstrap/compile.rs b/src/bootstrap/compile.rs
index 4a4e7adcbf3..1573134e35f 100644
--- a/src/bootstrap/compile.rs
+++ b/src/bootstrap/compile.rs
@@ -1260,6 +1260,7 @@ impl Step for Sysroot {
         };
         let sysroot = sysroot_dir(compiler.stage);
 
+        builder.verbose(&format!("Removing sysroot {} to avoid caching bugs", sysroot.display()));
         let _ = fs::remove_dir_all(&sysroot);
         t!(fs::create_dir_all(&sysroot));
 
diff --git a/src/bootstrap/test.rs b/src/bootstrap/test.rs
index 3814dc63ed4..ccf83974b8c 100644
--- a/src/bootstrap/test.rs
+++ b/src/bootstrap/test.rs
@@ -1448,7 +1448,7 @@ note: if you're sure you want to do this, please open an issue as to why. In the
             crate::detail_exit(1);
         }
 
-        let compiler = self.compiler;
+        let mut compiler = self.compiler;
         let target = self.target;
         let mode = self.mode;
         let suite = self.suite;
@@ -1461,15 +1461,28 @@ note: if you're sure you want to do this, please open an issue as to why. In the
             return;
         }
 
-        if suite == "debuginfo" {
-            builder
-                .ensure(dist::DebuggerScripts { sysroot: builder.sysroot(compiler), host: target });
-        }
+        // Support stage 1 ui-fulldeps. This is somewhat complicated: ui-fulldeps tests for the most
+        // part test the *API* of the compiler, not how it compiles a given file. As a result, we
+        // can run them against the stage 1 sources as long as we build them with the stage 0
+        // bootstrap compiler.
+        // NOTE: Only stage 1 is special cased because we need the rustc_private artifacts to match the
+        // running compiler in stage 2 when plugins run.
+        let stage_id = if suite == "ui-fulldeps" && compiler.stage == 1 {
+            compiler = builder.compiler(compiler.stage - 1, target);
+            format!("stage{}-{}", compiler.stage + 1, target)
+        } else {
+            format!("stage{}-{}", compiler.stage, target)
+        };
 
         if suite.ends_with("fulldeps") {
             builder.ensure(compile::Rustc::new(compiler, target));
         }
 
+        if suite == "debuginfo" {
+            builder
+                .ensure(dist::DebuggerScripts { sysroot: builder.sysroot(compiler), host: target });
+        }
+
         builder.ensure(compile::Std::new(compiler, target));
         // ensure that `libproc_macro` is available on the host.
         builder.ensure(compile::Std::new(compiler, compiler.host));
@@ -1528,7 +1541,7 @@ note: if you're sure you want to do this, please open an issue as to why. In the
         cmd.arg("--src-base").arg(builder.src.join("tests").join(suite));
         cmd.arg("--build-base").arg(testdir(builder, compiler.host).join(suite));
         cmd.arg("--sysroot-base").arg(builder.sysroot(compiler));
-        cmd.arg("--stage-id").arg(format!("stage{}-{}", compiler.stage, target));
+        cmd.arg("--stage-id").arg(stage_id);
         cmd.arg("--suite").arg(suite);
         cmd.arg("--mode").arg(mode);
         cmd.arg("--target").arg(target.rustc_target_arg());