Use `compiler_for_std` in `dist::Std`

4 files changed, 59 insertions, 59 deletions

diff --git a/src/bootstrap/src/core/build_steps/compile.rs b/src/bootstrap/src/core/build_steps/compile.rs
index bc978e1c4d0..72069df4cbd 100644
--- a/src/bootstrap/src/core/build_steps/compile.rs
+++ b/src/bootstrap/src/core/build_steps/compile.rs
@@ -150,7 +150,9 @@ impl Step for Std {
         trace!(force_recompile);
 
         run.builder.ensure(Std {
-            build_compiler: run.builder.compiler_for_std(run.builder.top_stage, run.target),
+            // Note: we don't use compiler_for_std here, so that `x build library --stage 2`
+            // builds a stage2 rustc.
+            build_compiler: run.builder.compiler(run.builder.top_stage, builder.host_target),
             target: run.target,
             crates,
             force_recompile,
diff --git a/src/bootstrap/src/core/build_steps/dist.rs b/src/bootstrap/src/core/build_steps/dist.rs
index 1320c3f65d5..a76bef93317 100644
--- a/src/bootstrap/src/core/build_steps/dist.rs
+++ b/src/bootstrap/src/core/build_steps/dist.rs
@@ -769,22 +769,7 @@ pub struct Std {
 
 impl Std {
     pub fn new(builder: &Builder<'_>, target: TargetSelection) -> Self {
-        // This is an important optimization mainly for CI.
-        // Normally, to build stage N libstd, we need stage N rustc.
-        // However, if we know that we will uplift libstd from stage 1 anyway, building the stage N
-        // rustc can be wasteful.
-        // In particular, if we do a cross-compiling dist stage 2 build from T1 to T2, we need:
-        // - stage 2 libstd for T2 (uplifted from stage 1, where it was built by T1 rustc)
-        // - stage 2 rustc for T2
-        // However, without this optimization, we would also build stage 2 rustc for **T1**, which
-        // is completely wasteful.
-        let build_compiler =
-            if compile::Std::should_be_uplifted_from_stage_1(builder, builder.top_stage, target) {
-                builder.compiler(1, builder.host_target)
-            } else {
-                builder.compiler(builder.top_stage, builder.host_target)
-            };
-        Std { build_compiler, target }
+        Std { build_compiler: builder.compiler_for_std(builder.top_stage, target), target }
     }
 }
 
diff --git a/src/bootstrap/src/core/builder/mod.rs b/src/bootstrap/src/core/builder/mod.rs
index 02ca1a33516..4f37e0edbad 100644
--- a/src/bootstrap/src/core/builder/mod.rs
+++ b/src/bootstrap/src/core/builder/mod.rs
@@ -1360,6 +1360,21 @@ impl<'a> Builder<'a> {
         self.ensure(compile::Assemble { target_compiler: Compiler::new(stage, host) })
     }
 
+    /// This function can be used to provide a build compiler for building
+    /// the standard library, in order to avoid unnecessary rustc builds in case where std uplifting
+    /// would happen anyway.
+    ///
+    /// This is an important optimization mainly for CI.
+    ///
+    /// Normally, to build stage N libstd, we need stage N rustc.
+    /// However, if we know that we will uplift libstd from stage 1 anyway, building the stage N
+    /// rustc can be wasteful.
+    /// In particular, if we do a cross-compiling dist stage 2 build from target1 to target2,
+    /// we need:
+    /// - stage 2 libstd for target2 (uplifted from stage 1, where it was built by target1 rustc)
+    /// - stage 2 rustc for target2
+    /// However, without this optimization, we would also build stage 2 rustc for **target1**,
+    /// which is completely wasteful.
     pub fn compiler_for_std(&self, stage: u32, target: TargetSelection) -> Compiler {
         if compile::Std::should_be_uplifted_from_stage_1(self, stage, target) {
             self.compiler(1, self.host_target)
diff --git a/src/bootstrap/src/core/builder/tests.rs b/src/bootstrap/src/core/builder/tests.rs
index 5c8cec4615d..491df10519a 100644
--- a/src/bootstrap/src/core/builder/tests.rs
+++ b/src/bootstrap/src/core/builder/tests.rs
@@ -1122,9 +1122,8 @@ mod snapshot {
         [doc] book/2018-edition (book) <host>
         [build] rustdoc 1 <host>
         [doc] rustc 1 <host> -> standalone 2 <host>
+        [doc] rustc 1 <host> -> std 1 <host> crates=[alloc,compiler_builtins,core,panic_abort,panic_unwind,proc_macro,rustc-std-workspace-core,std,std_detect,sysroot,test,unwind]
         [build] rustc 1 <host> -> rustc 2 <host>
-        [build] rustdoc 2 <host>
-        [doc] rustc 2 <host> -> std 2 <host> crates=[alloc,compiler_builtins,core,panic_abort,panic_unwind,proc_macro,rustc-std-workspace-core,std,std_detect,sysroot,test,unwind]
         [build] rustc 1 <host> -> error-index 2 <host>
         [doc] rustc 1 <host> -> error-index 2 <host>
         [doc] nomicon (book) <host>
@@ -1141,9 +1140,10 @@ mod snapshot {
         [doc] rustc 1 <host> -> releases 2 <host>
         [build] rustc 0 <host> -> RustInstaller 1 <host>
         [dist] docs <host>
-        [doc] rustc 2 <host> -> std 2 <host> crates=[]
-        [dist] rustc 2 <host> -> json-docs 3 <host>
+        [doc] rustc 1 <host> -> std 1 <host> crates=[]
+        [dist] rustc 1 <host> -> json-docs 2 <host>
         [dist] mingw <host>
+        [build] rustdoc 2 <host>
         [build] rustc 0 <host> -> GenerateCopyright 1 <host>
         [dist] rustc <host>
         [dist] rustc 1 <host> -> std 1 <host>
@@ -1183,12 +1183,11 @@ mod snapshot {
         [doc] book/2018-edition (book) <host>
         [build] rustdoc 1 <host>
         [doc] rustc 1 <host> -> standalone 2 <host>
+        [doc] rustc 1 <host> -> std 1 <host> crates=[alloc,compiler_builtins,core,panic_abort,panic_unwind,proc_macro,rustc-std-workspace-core,std,std_detect,sysroot,test,unwind]
         [build] rustc 1 <host> -> rustc 2 <host>
         [build] rustc 1 <host> -> LldWrapper 2 <host>
         [build] rustc 1 <host> -> WasmComponentLd 2 <host>
         [build] rustc 1 <host> -> LlvmBitcodeLinker 2 <host>
-        [build] rustdoc 2 <host>
-        [doc] rustc 2 <host> -> std 2 <host> crates=[alloc,compiler_builtins,core,panic_abort,panic_unwind,proc_macro,rustc-std-workspace-core,std,std_detect,sysroot,test,unwind]
         [build] rustc 1 <host> -> error-index 2 <host>
         [doc] rustc 1 <host> -> error-index 2 <host>
         [doc] nomicon (book) <host>
@@ -1205,9 +1204,10 @@ mod snapshot {
         [doc] rustc 1 <host> -> releases 2 <host>
         [build] rustc 0 <host> -> RustInstaller 1 <host>
         [dist] docs <host>
-        [doc] rustc 2 <host> -> std 2 <host> crates=[]
-        [dist] rustc 2 <host> -> json-docs 3 <host>
+        [doc] rustc 1 <host> -> std 1 <host> crates=[]
+        [dist] rustc 1 <host> -> json-docs 2 <host>
         [dist] mingw <host>
+        [build] rustdoc 2 <host>
         [build] rustc 1 <host> -> rust-analyzer-proc-macro-srv 2 <host>
         [build] rustc 0 <host> -> GenerateCopyright 1 <host>
         [dist] rustc <host>
@@ -1228,6 +1228,8 @@ mod snapshot {
         [build] rustc 1 <host> -> miri 2 <host>
         [build] rustc 1 <host> -> cargo-miri 2 <host>
         [dist] rustc 1 <host> -> miri 2 <host>
+        [doc] rustc 2 <host> -> std 2 <host> crates=[]
+        [dist] rustc 2 <host> -> json-docs 3 <host>
         [dist] rustc 1 <host> -> extended 2 <host>
         [dist] reproducible-artifacts <host>
         ");
@@ -1261,10 +1263,9 @@ mod snapshot {
         [doc] book/2018-edition (book) <target1>
         [doc] rustc 1 <host> -> standalone 2 <host>
         [doc] rustc 1 <host> -> standalone 2 <target1>
+        [doc] rustc 1 <host> -> std 1 <host> crates=[alloc,compiler_builtins,core,panic_abort,panic_unwind,proc_macro,rustc-std-workspace-core,std,std_detect,sysroot,test,unwind]
+        [doc] rustc 1 <host> -> std 1 <target1> crates=[alloc,compiler_builtins,core,panic_abort,panic_unwind,proc_macro,rustc-std-workspace-core,std,std_detect,sysroot,test,unwind]
         [build] rustc 1 <host> -> rustc 2 <host>
-        [build] rustdoc 2 <host>
-        [doc] rustc 2 <host> -> std 2 <host> crates=[alloc,compiler_builtins,core,panic_abort,panic_unwind,proc_macro,rustc-std-workspace-core,std,std_detect,sysroot,test,unwind]
-        [doc] rustc 2 <host> -> std 2 <target1> crates=[alloc,compiler_builtins,core,panic_abort,panic_unwind,proc_macro,rustc-std-workspace-core,std,std_detect,sysroot,test,unwind]
         [build] rustc 1 <host> -> error-index 2 <host>
         [doc] rustc 1 <host> -> error-index 2 <host>
         [doc] nomicon (book) <host>
@@ -1292,8 +1293,9 @@ mod snapshot {
         [build] rustc 0 <host> -> RustInstaller 1 <host>
         [dist] docs <host>
         [dist] docs <target1>
-        [doc] rustc 2 <host> -> std 2 <host> crates=[]
-        [dist] rustc 2 <host> -> json-docs 3 <host>
+        [doc] rustc 1 <host> -> std 1 <host> crates=[]
+        [dist] rustc 1 <host> -> json-docs 2 <host>
+        [build] rustdoc 2 <host>
         [doc] rustc 2 <host> -> std 2 <target1> crates=[]
         [dist] rustc 2 <host> -> json-docs 3 <target1>
         [dist] mingw <host>
@@ -1331,9 +1333,8 @@ mod snapshot {
         [doc] book/2018-edition (book) <host>
         [build] rustdoc 1 <host>
         [doc] rustc 1 <host> -> standalone 2 <host>
+        [doc] rustc 1 <host> -> std 1 <host> crates=[alloc,compiler_builtins,core,panic_abort,panic_unwind,proc_macro,rustc-std-workspace-core,std,std_detect,sysroot,test,unwind]
         [build] rustc 1 <host> -> rustc 2 <host>
-        [build] rustdoc 2 <host>
-        [doc] rustc 2 <host> -> std 2 <host> crates=[alloc,compiler_builtins,core,panic_abort,panic_unwind,proc_macro,rustc-std-workspace-core,std,std_detect,sysroot,test,unwind]
         [build] rustc 1 <host> -> error-index 2 <host>
         [doc] rustc 1 <host> -> error-index 2 <host>
         [build] llvm <target1>
@@ -1356,9 +1357,10 @@ mod snapshot {
         [doc] rustc 1 <host> -> releases 2 <host>
         [build] rustc 0 <host> -> RustInstaller 1 <host>
         [dist] docs <host>
-        [doc] rustc 2 <host> -> std 2 <host> crates=[]
-        [dist] rustc 2 <host> -> json-docs 3 <host>
+        [doc] rustc 1 <host> -> std 1 <host> crates=[]
+        [dist] rustc 1 <host> -> json-docs 2 <host>
         [dist] mingw <host>
+        [build] rustdoc 2 <host>
         [build] rustc 0 <host> -> GenerateCopyright 1 <host>
         [dist] rustc <host>
         [build] rustdoc 2 <target1>
@@ -1401,10 +1403,9 @@ mod snapshot {
         [doc] book/2018-edition (book) <target1>
         [doc] rustc 1 <host> -> standalone 2 <host>
         [doc] rustc 1 <host> -> standalone 2 <target1>
+        [doc] rustc 1 <host> -> std 1 <host> crates=[alloc,compiler_builtins,core,panic_abort,panic_unwind,proc_macro,rustc-std-workspace-core,std,std_detect,sysroot,test,unwind]
+        [doc] rustc 1 <host> -> std 1 <target1> crates=[alloc,compiler_builtins,core,panic_abort,panic_unwind,proc_macro,rustc-std-workspace-core,std,std_detect,sysroot,test,unwind]
         [build] rustc 1 <host> -> rustc 2 <host>
-        [build] rustdoc 2 <host>
-        [doc] rustc 2 <host> -> std 2 <host> crates=[alloc,compiler_builtins,core,panic_abort,panic_unwind,proc_macro,rustc-std-workspace-core,std,std_detect,sysroot,test,unwind]
-        [doc] rustc 2 <host> -> std 2 <target1> crates=[alloc,compiler_builtins,core,panic_abort,panic_unwind,proc_macro,rustc-std-workspace-core,std,std_detect,sysroot,test,unwind]
         [build] rustc 1 <host> -> error-index 2 <host>
         [doc] rustc 1 <host> -> error-index 2 <host>
         [build] llvm <target1>
@@ -1437,12 +1438,13 @@ mod snapshot {
         [build] rustc 0 <host> -> RustInstaller 1 <host>
         [dist] docs <host>
         [dist] docs <target1>
-        [doc] rustc 2 <host> -> std 2 <host> crates=[]
-        [dist] rustc 2 <host> -> json-docs 3 <host>
-        [doc] rustc 2 <host> -> std 2 <target1> crates=[]
-        [dist] rustc 2 <host> -> json-docs 3 <target1>
+        [doc] rustc 1 <host> -> std 1 <host> crates=[]
+        [dist] rustc 1 <host> -> json-docs 2 <host>
+        [doc] rustc 1 <host> -> std 1 <target1> crates=[]
+        [dist] rustc 1 <host> -> json-docs 2 <target1>
         [dist] mingw <host>
         [dist] mingw <target1>
+        [build] rustdoc 2 <host>
         [build] rustc 0 <host> -> GenerateCopyright 1 <host>
         [dist] rustc <host>
         [build] rustdoc 2 <target1>
@@ -1480,9 +1482,7 @@ mod snapshot {
         [build] rustdoc 1 <host>
         [build] rustc 1 <host> -> std 1 <host>
         [doc] rustc 1 <host> -> standalone 2 <target1>
-        [build] rustc 1 <host> -> rustc 2 <host>
-        [build] rustdoc 2 <host>
-        [doc] rustc 2 <host> -> std 2 <target1> crates=[alloc,compiler_builtins,core,panic_abort,panic_unwind,proc_macro,rustc-std-workspace-core,std,std_detect,sysroot,test,unwind]
+        [doc] rustc 1 <host> -> std 1 <target1> crates=[alloc,compiler_builtins,core,panic_abort,panic_unwind,proc_macro,rustc-std-workspace-core,std,std_detect,sysroot,test,unwind]
         [doc] nomicon (book) <target1>
         [doc] rustc 1 <host> -> reference (book) 2 <target1>
         [doc] rustdoc (book) <target1>
@@ -1495,6 +1495,8 @@ mod snapshot {
         [doc] rustc 1 <host> -> releases 2 <target1>
         [build] rustc 0 <host> -> RustInstaller 1 <host>
         [dist] docs <target1>
+        [build] rustc 1 <host> -> rustc 2 <host>
+        [build] rustdoc 2 <host>
         [doc] rustc 2 <host> -> std 2 <target1> crates=[]
         [dist] rustc 2 <host> -> json-docs 3 <target1>
         [dist] mingw <target1>
@@ -1527,10 +1529,7 @@ mod snapshot {
         [build] rustdoc 1 <host>
         [build] rustc 1 <host> -> std 1 <host>
         [doc] rustc 1 <host> -> standalone 2 <target1>
-        [build] rustc 1 <host> -> rustc 2 <host>
-        [build] rustc 1 <host> -> WasmComponentLd 2 <host>
-        [build] rustdoc 2 <host>
-        [doc] rustc 2 <host> -> std 2 <target1> crates=[alloc,compiler_builtins,core,panic_abort,panic_unwind,proc_macro,rustc-std-workspace-core,std,std_detect,sysroot,test,unwind]
+        [doc] rustc 1 <host> -> std 1 <target1> crates=[alloc,compiler_builtins,core,panic_abort,panic_unwind,proc_macro,rustc-std-workspace-core,std,std_detect,sysroot,test,unwind]
         [build] llvm <target1>
         [build] rustc 1 <host> -> rustc 2 <target1>
         [build] rustc 1 <host> -> WasmComponentLd 2 <target1>
@@ -1550,8 +1549,8 @@ mod snapshot {
         [doc] rustc 1 <host> -> releases 2 <target1>
         [build] rustc 0 <host> -> RustInstaller 1 <host>
         [dist] docs <target1>
-        [doc] rustc 2 <host> -> std 2 <target1> crates=[]
-        [dist] rustc 2 <host> -> json-docs 3 <target1>
+        [doc] rustc 1 <host> -> std 1 <target1> crates=[]
+        [dist] rustc 1 <host> -> json-docs 2 <target1>
         [dist] mingw <target1>
         [build] rustdoc 2 <target1>
         [build] rustc 1 <host> -> rust-analyzer-proc-macro-srv 2 <target1>
@@ -1583,7 +1582,7 @@ mod snapshot {
     }
 
     /// Simulates e.g. the powerpc64 builder, which is fully cross-compiled from x64, but it does
-    /// not build docs. Crutically, it shouldn't build host stage 2 rustc.
+    /// not build docs. Crucially, it shouldn't build host stage 2 rustc.
     ///
     /// This is a regression test for <https://github.com/rust-lang/rust/issues/138123>
     /// and <https://github.com/rust-lang/rust/issues/138004>.
@@ -1673,10 +1672,9 @@ mod snapshot {
         [doc] book/2018-edition (book) <host>
         [build] rustdoc 1 <host>
         [doc] rustc 1 <host> -> standalone 2 <host>
+        [doc] rustc 1 <host> -> std 1 <host> crates=[alloc,compiler_builtins,core,panic_abort,panic_unwind,proc_macro,rustc-std-workspace-core,std,std_detect,sysroot,test,unwind]
         [build] rustc 1 <host> -> rustc 2 <host>
         [build] rustc 1 <host> -> rustc_codegen_cranelift 2 <host>
-        [build] rustdoc 2 <host>
-        [doc] rustc 2 <host> -> std 2 <host> crates=[alloc,compiler_builtins,core,panic_abort,panic_unwind,proc_macro,rustc-std-workspace-core,std,std_detect,sysroot,test,unwind]
         [build] rustc 1 <host> -> error-index 2 <host>
         [doc] rustc 1 <host> -> error-index 2 <host>
         [doc] nomicon (book) <host>
@@ -1693,9 +1691,10 @@ mod snapshot {
         [doc] rustc 1 <host> -> releases 2 <host>
         [build] rustc 0 <host> -> RustInstaller 1 <host>
         [dist] docs <host>
-        [doc] rustc 2 <host> -> std 2 <host> crates=[]
-        [dist] rustc 2 <host> -> json-docs 3 <host>
+        [doc] rustc 1 <host> -> std 1 <host> crates=[]
+        [dist] rustc 1 <host> -> json-docs 2 <host>
         [dist] mingw <host>
+        [build] rustdoc 2 <host>
         [build] rustc 0 <host> -> GenerateCopyright 1 <host>
         [dist] rustc <host>
         [dist] rustc 1 <host> -> rustc_codegen_cranelift 2 <host>
@@ -1755,9 +1754,8 @@ mod snapshot {
         [doc] book/2018-edition (book) <host>
         [build] rustdoc 1 <host>
         [doc] rustc 1 <host> -> standalone 2 <host>
+        [doc] rustc 1 <host> -> std 1 <host> crates=[alloc,compiler_builtins,core,panic_abort,panic_unwind,proc_macro,rustc-std-workspace-core,std,std_detect,sysroot,test,unwind]
         [build] rustc 1 <host> -> rustc 2 <host>
-        [build] rustdoc 2 <host>
-        [doc] rustc 2 <host> -> std 2 <host> crates=[alloc,compiler_builtins,core,panic_abort,panic_unwind,proc_macro,rustc-std-workspace-core,std,std_detect,sysroot,test,unwind]
         [build] rustc 1 <host> -> error-index 2 <host>
         [doc] rustc 1 <host> -> error-index 2 <host>
         [doc] nomicon (book) <host>
@@ -2467,10 +2465,9 @@ mod snapshot {
         [doc] book/2018-edition (book) <host>
         [build] rustdoc 1 <host>
         [doc] rustc 1 <host> -> standalone 2 <host>
+        [doc] rustc 1 <host> -> std 1 <host> crates=[alloc,compiler_builtins,core,panic_abort,panic_unwind,proc_macro,rustc-std-workspace-core,std,std_detect,sysroot,test,unwind]
         [build] rustc 1 <host> -> rustc 2 <host>
         [build] rustc 1 <host> -> WasmComponentLd 2 <host>
-        [build] rustdoc 2 <host>
-        [doc] rustc 2 <host> -> std 2 <host> crates=[alloc,compiler_builtins,core,panic_abort,panic_unwind,proc_macro,rustc-std-workspace-core,std,std_detect,sysroot,test,unwind]
         [build] rustc 1 <host> -> error-index 2 <host>
         [doc] rustc 1 <host> -> error-index 2 <host>
         [doc] nomicon (book) <host>
@@ -2488,6 +2485,7 @@ mod snapshot {
         [build] rustc 0 <host> -> RustInstaller 1 <host>
         [dist] docs <host>
         [dist] rustc 1 <host> -> std 1 <host>
+        [build] rustdoc 2 <host>
         [build] rustc 1 <host> -> rust-analyzer-proc-macro-srv 2 <host>
         [build] rustc 0 <host> -> GenerateCopyright 1 <host>
         [dist] rustc <host>