Add bootstrap check snapshot tests

src/bootstrap/src/core/build_steps/check.rs

@@ -5,7 +5,7 @@ use crate::core::build_steps::compile::{
 };
 use crate::core::build_steps::tool::{COMPILETEST_ALLOW_FEATURES, SourceType, prepare_tool_cargo};
 use crate::core::builder::{
-    self, Alias, Builder, Kind, RunConfig, ShouldRun, Step, crate_description,
+    self, Alias, Builder, Kind, RunConfig, ShouldRun, Step, StepMetadata, crate_description,
 };
 use crate::core::config::TargetSelection;
 use crate::utils::build_stamp::{self, BuildStamp};
@@ -167,6 +167,10 @@ impl Step for Std {
         let _guard = builder.msg_check("library test/bench/example targets", target, Some(stage));
         run_cargo(builder, cargo, builder.config.free_args.clone(), &stamp, vec![], true, false);
     }
+
+    fn metadata(&self) -> Option<StepMetadata> {
+        Some(StepMetadata::check("std", self.target))
+    }
 }
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
@@ -258,6 +262,10 @@ impl Step for Rustc {
         let hostdir = builder.sysroot_target_libdir(compiler, compiler.host);
         add_to_sysroot(builder, &libdir, &hostdir, &stamp);
     }
+
+    fn metadata(&self) -> Option<StepMetadata> {
+        Some(StepMetadata::check("rustc", self.target))
+    }
 }
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
@@ -315,6 +323,10 @@ impl Step for CodegenBackend {
 
         run_cargo(builder, cargo, builder.config.free_args.clone(), &stamp, vec![], true, false);
     }
+
+    fn metadata(&self) -> Option<StepMetadata> {
+        Some(StepMetadata::check(self.backend, self.target))
+    }
 }
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
@@ -373,6 +385,10 @@ impl Step for RustAnalyzer {
         let _guard = builder.msg_check("rust-analyzer artifacts", target, None);
         run_cargo(builder, cargo, builder.config.free_args.clone(), &stamp, vec![], true, false);
     }
+
+    fn metadata(&self) -> Option<StepMetadata> {
+        Some(StepMetadata::check("rust-analyzer", self.target))
+    }
 }
 
 /// Compiletest is implicitly "checked" when it gets built in order to run tests,
@@ -432,6 +448,10 @@ impl Step for Compiletest {
         let _guard = builder.msg_check("compiletest artifacts", self.target, None);
         run_cargo(builder, cargo, builder.config.free_args.clone(), &stamp, vec![], true, false);
     }
+
+    fn metadata(&self) -> Option<StepMetadata> {
+        Some(StepMetadata::check("compiletest", self.target))
+    }
 }
 
 macro_rules! tool_check_step {
@@ -467,6 +487,10 @@ macro_rules! tool_check_step {
                 let Self { target } = self;
                 run_tool_check_step(builder, target, stringify!($name), $path);
             }
+
+            fn metadata(&self) -> Option<StepMetadata> {
+                Some(StepMetadata::check(stringify!($name), self.target))
+            }
         }
     }
 }

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

@@ -306,11 +306,7 @@ impl Step for Std {
     }
 
     fn metadata(&self) -> Option<StepMetadata> {
-        Some(
-            StepMetadata::build("std", self.target)
-                .built_by(self.compiler)
-                .stage(self.compiler.stage),
-        )
+        Some(StepMetadata::build("std", self.target).built_by(self.compiler))
     }
 }
 
@@ -1186,11 +1182,7 @@ impl Step for Rustc {
     }
 
     fn metadata(&self) -> Option<StepMetadata> {
-        Some(
-            StepMetadata::build("rustc", self.target)
-                .built_by(self.build_compiler)
-                .stage(self.build_compiler.stage + 1),
-        )
+        Some(StepMetadata::build("rustc", self.target).built_by(self.build_compiler))
     }
 }
 

src/bootstrap/src/core/build_steps/tool.rs

@@ -1195,7 +1195,6 @@ macro_rules! tool_extended {
                 Some(
                     StepMetadata::build($tool_name, self.target)
                         .built_by(self.compiler.with_stage(self.compiler.stage.saturating_sub(1)))
-                        .stage(self.compiler.stage)
                 )
             }
         }

src/bootstrap/src/core/builder/mod.rs

@@ -153,6 +153,10 @@ impl StepMetadata {
         Self::new(name, target, Kind::Build)
     }
 
+    pub fn check(name: &'static str, target: TargetSelection) -> Self {
+        Self::new(name, target, Kind::Check)
+    }
+
     pub fn doc(name: &'static str, target: TargetSelection) -> Self {
         Self::new(name, target, Kind::Doc)
     }
@@ -178,6 +182,14 @@ impl StepMetadata {
         self.stage = Some(stage);
         self
     }
+
+    pub fn get_stage(&self) -> Option<u32> {
+        self.stage.or(self
+            .built_by
+            // For std, its stage corresponds to the stage of the compiler that builds it.
+            // For everything else, a stage N things gets built by a stage N-1 compiler.
+            .map(|compiler| if self.name == "std" { compiler.stage } else { compiler.stage + 1 }))
+    }
 }
 
 pub struct RunConfig<'a> {