For "stage 1" ui-fulldeps, use the stage 1 compiler to query target info

Testing ui-fulldeps in "stage 1" actually uses the stage 0 compiler, so that
test programs can link against stage 1 rustc crates.

Unfortunately, using the stage 0 compiler causes problems when compiletest
tries to obtain target information from the compiler, but the output format has
changed since the last bootstrap beta bump.

We can work around this by also providing compiletest with a stage 1 compiler,
and having it use that compiler to query for target information.

1 files changed, 8 insertions, 0 deletions

diff --git a/src/bootstrap/src/core/build_steps/test.rs b/src/bootstrap/src/core/build_steps/test.rs
index ffc5dfad459..8bee00a9c13 100644
--- a/src/bootstrap/src/core/build_steps/test.rs
+++ b/src/bootstrap/src/core/build_steps/test.rs
@@ -1663,7 +1663,11 @@ NOTE: if you're sure you want to do this, please open an issue as to why. In the
         // 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 query_compiler;
         let (stage, stage_id) = if suite == "ui-fulldeps" && compiler.stage == 1 {
+            // Even when using the stage 0 compiler, we also need to provide the stage 1 compiler
+            // so that compiletest can query it for target information.
+            query_compiler = Some(compiler);
             // At stage 0 (stage - 1) we are using the stage0 compiler. Using `self.target` can lead
             // finding an incorrect compiler path on cross-targets, as the stage 0 is always equal to
             // `build.build` in the configuration.
@@ -1672,6 +1676,7 @@ NOTE: if you're sure you want to do this, please open an issue as to why. In the
             let test_stage = compiler.stage + 1;
             (test_stage, format!("stage{test_stage}-{build}"))
         } else {
+            query_compiler = None;
             let stage = compiler.stage;
             (stage, format!("stage{stage}-{target}"))
         };
@@ -1716,6 +1721,9 @@ NOTE: if you're sure you want to do this, please open an issue as to why. In the
         cmd.arg("--compile-lib-path").arg(builder.rustc_libdir(compiler));
         cmd.arg("--run-lib-path").arg(builder.sysroot_target_libdir(compiler, target));
         cmd.arg("--rustc-path").arg(builder.rustc(compiler));
+        if let Some(query_compiler) = query_compiler {
+            cmd.arg("--query-rustc-path").arg(builder.rustc(query_compiler));
+        }
 
         // Minicore auxiliary lib for `no_core` tests that need `core` stubs in cross-compilation
         // scenarios.