Unrolled build for rust-lang#137882

Rollup merge of rust-lang#137882 - onur-ozkan:remove-extra-compiler-stage, r=Kobzol

do not build additional stage on compiler paths

When calling `x build compiler (or rustc) --stage N` bootstrap builds stage N+1 compiler, which is clearly not what we requested. This doesn't happen when running `x build --stage N` without explicitly targeting the compiler.

The changes applied fix this issue.

r? ghost

src/bootstrap/src/core/build_steps/compile.rs

@@ -994,7 +994,9 @@ impl Step for Rustc {
     fn make_run(run: RunConfig<'_>) {
         let crates = run.cargo_crates_in_set();
         run.builder.ensure(Rustc {
-            compiler: run.builder.compiler(run.builder.top_stage, run.build_triple()),
+            compiler: run
+                .builder
+                .compiler(run.builder.top_stage.saturating_sub(1), run.build_triple()),
             target: run.target,
             crates,
         });
@@ -1911,7 +1913,7 @@ impl Step for Assemble {
 
     fn make_run(run: RunConfig<'_>) {
         run.builder.ensure(Assemble {
-            target_compiler: run.builder.compiler(run.builder.top_stage + 1, run.target),
+            target_compiler: run.builder.compiler(run.builder.top_stage, run.target),
         });
     }
 

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

@@ -653,6 +653,20 @@ mod dist {
             &["compiler/rustc".into(), "library".into()],
         );
 
+        assert_eq!(builder.config.stage, 2);
+
+        // `compile::Rustc` includes one-stage-off compiler information as the target compiler
+        // artifacts get copied from there to the target stage sysroot.
+        // For example, `stage2/bin/rustc` gets copied from the `stage1-rustc` build directory.
+        assert_eq!(
+            first(builder.cache.all::<compile::Rustc>()),
+            &[
+                rustc!(TEST_TRIPLE_1 => TEST_TRIPLE_1, stage = 0),
+                rustc!(TEST_TRIPLE_1 => TEST_TRIPLE_1, stage = 1),
+                rustc!(TEST_TRIPLE_1 => TEST_TRIPLE_2, stage = 1),
+            ]
+        );
+
         assert_eq!(
             first(builder.cache.all::<compile::Std>()),
             &[
@@ -664,15 +678,34 @@ mod dist {
                 std!(TEST_TRIPLE_1 => TEST_TRIPLE_3, stage = 2),
             ]
         );
-        assert_eq!(builder.cache.all::<compile::Assemble>().len(), 5);
+
         assert_eq!(
-            first(builder.cache.all::<compile::Rustc>()),
+            first(builder.cache.all::<compile::Assemble>()),
             &[
-                rustc!(TEST_TRIPLE_1 => TEST_TRIPLE_1, stage = 0),
-                rustc!(TEST_TRIPLE_1 => TEST_TRIPLE_1, stage = 1),
-                rustc!(TEST_TRIPLE_1 => TEST_TRIPLE_1, stage = 2),
-                rustc!(TEST_TRIPLE_1 => TEST_TRIPLE_2, stage = 1),
-                rustc!(TEST_TRIPLE_1 => TEST_TRIPLE_2, stage = 2),
+                compile::Assemble {
+                    target_compiler: Compiler {
+                        host: TargetSelection::from_user(TEST_TRIPLE_1),
+                        stage: 0
+                    }
+                },
+                compile::Assemble {
+                    target_compiler: Compiler {
+                        host: TargetSelection::from_user(TEST_TRIPLE_1),
+                        stage: 1
+                    }
+                },
+                compile::Assemble {
+                    target_compiler: Compiler {
+                        host: TargetSelection::from_user(TEST_TRIPLE_1),
+                        stage: 2
+                    }
+                },
+                compile::Assemble {
+                    target_compiler: Compiler {
+                        host: TargetSelection::from_user(TEST_TRIPLE_2),
+                        stage: 2
+                    }
+                },
             ]
         );
     }