Remove usage of compiler_for from the compile::Std step

Author: Kobzol

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

@@ -203,51 +203,31 @@ impl Step for Std {
 
         let mut target_deps = builder.ensure(StartupObjects { compiler: build_compiler, target });
 
-        let compiler_to_use =
-            builder.compiler_for(build_compiler.stage, build_compiler.host, target);
-        trace!(?compiler_to_use);
-
-        if compiler_to_use != build_compiler
-            // Never uplift std unless we have compiled stage 1; if stage 1 is compiled,
-            // uplift it from there.
-            //
-            // FIXME: improve `fn compiler_for` to avoid adding stage condition here.
-            && build_compiler.stage > 1
+        // Stage of the stdlib that we're building
+        let stage = build_compiler.stage;
+
+        // If we're building a stage2+ libstd, full bootstrap is
+        // disabled and we're not cross-compiling, then simply uplift a previously built
+        // stage1 library.
+        if build_compiler.stage > 1
+            && !builder.config.full_bootstrap
+            && target == builder.host_target
         {
-            trace!(
-                ?compiler_to_use,
-                ?build_compiler,
-                "compiler != compiler_to_use, uplifting library"
-            );
-
-            builder.std(compiler_to_use, target);
-            let msg = if compiler_to_use.host == target {
-                format!(
-                    "Uplifting library (stage{} -> stage{})",
-                    compiler_to_use.stage, build_compiler.stage
-                )
-            } else {
-                format!(
-                    "Uplifting library (stage{}:{} -> stage{}:{})",
-                    compiler_to_use.stage, compiler_to_use.host, build_compiler.stage, target
-                )
-            };
-            builder.info(&msg);
+            let build_compiler_for_std_to_uplift = builder.compiler(1, builder.host_target);
+            builder.std(build_compiler_for_std_to_uplift, target);
+            builder.info(&format!(
+                "Uplifting library (stage{} -> stage{stage})",
+                build_compiler_for_std_to_uplift.stage
+            ));
 
             // Even if we're not building std this stage, the new sysroot must
             // still contain the third party objects needed by various targets.
             self.copy_extra_objects(builder, &build_compiler, target);
 
-            builder.ensure(StdLink::from_std(self, compiler_to_use));
+            builder.ensure(StdLink::from_std(self, build_compiler_for_std_to_uplift));
             return;
         }
 
-        trace!(
-            ?compiler_to_use,
-            ?build_compiler,
-            "compiler == compiler_to_use, handling not-cross-compile scenario"
-        );
-
         target_deps.extend(self.copy_extra_objects(builder, &build_compiler, target));
 
         // We build a sysroot for mir-opt tests using the same trick that Miri does: A check build

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

@@ -588,10 +588,10 @@ mod snapshot {
         [build] rustc 1 <host> -> std 1 <host>
         [build] rustc 1 <host> -> rustc 2 <host>
         [build] rustc 2 <host> -> std 2 <host>
-        [build] rustc 1 <host> -> std 1 <target1>
         [build] rustc 2 <host> -> std 2 <target1>
         [build] rustdoc 2 <host>
         [build] llvm <target1>
+        [build] rustc 1 <host> -> std 1 <target1>
         [build] rustc 1 <host> -> rustc 2 <target1>
         [build] rustdoc 2 <target1>
         ");
@@ -730,9 +730,9 @@ mod snapshot {
         [build] rustc 1 <host> -> rustc 2 <host>
         [build] rustc 1 <host> -> LldWrapper 2 <host>
         [build] rustc 1 <host> -> LlvmBitcodeLinker 2 <host>
-        [build] rustc 1 <host> -> std 1 <target1>
         [build] rustc 2 <host> -> std 2 <target1>
         [build] llvm <target1>
+        [build] rustc 1 <host> -> std 1 <target1>
         [build] rustc 1 <host> -> rustc 2 <target1>
         [build] rustc 1 <host> -> LldWrapper 2 <target1>
         [build] rustc 1 <host> -> LlvmBitcodeLinker 2 <target1>