Add test for check cross-compilation

Author: Kobzol

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

@@ -253,7 +253,7 @@ fn prepare_compiler_for_check(
             // library crates (e.g. compiletest needs libtest).
             let build_compiler = builder.compiler(builder.top_stage, host);
             builder.std(build_compiler, host);
-            builder.std(build_compiler, target);
+            builder.ensure(Std::new(build_compiler, target));
             build_compiler
         }
         Mode::ToolRustc | Mode::Codegen => {

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

@@ -1294,6 +1294,38 @@ mod snapshot {
         ");
     }
 
+    #[test]
+    fn check_cross_compile() {
+        let ctx = TestCtx::new();
+        insta::assert_snapshot!(
+            ctx.config("check")
+                .stage(2)
+                .targets(&[TEST_TRIPLE_1])
+                .hosts(&[TEST_TRIPLE_1])
+                .render_steps(), @r"
+        [build] llvm <host>
+        [build] rustc 0 <host> -> rustc 1 <host>
+        [build] rustc 1 <host> -> std 1 <host>
+        [build] rustc 1 <host> -> std 1 <target1>
+        [build] llvm <target1>
+        [check] rustc 1 <host> -> rustc 2 <target1>
+        [check] rustc 1 <host> -> Rustdoc 2 <target1>
+        [check] rustc 1 <host> -> cranelift 2 <target1>
+        [check] rustc 1 <host> -> gcc 2 <target1>
+        [check] rustc 1 <host> -> Clippy 2 <target1>
+        [check] rustc 1 <host> -> Miri 2 <target1>
+        [check] rustc 1 <host> -> CargoMiri 2 <target1>
+        [check] rustc 0 <host> -> MiroptTestTools 1 <target1>
+        [check] rustc 1 <host> -> Rustfmt 2 <target1>
+        [check] rustc 1 <host> -> rust-analyzer 2 <target1>
+        [build] rustc 1 <host> -> rustc 2 <host>
+        [build] rustc 2 <host> -> std 2 <host>
+        [check] rustc 2 <host> -> std 2 <target1>
+        [check] rustc 2 <host> -> TestFloatParse 3 <target1>
+        [check] rustc 0 <host> -> FeaturesStatusDump 1 <target1>
+        ");
+    }
+
     #[test]
     fn check_library_no_explicit_stage() {
         let ctx = TestCtx::new();
@@ -1344,6 +1376,21 @@ mod snapshot {
         ");
     }
 
+    #[test]
+    fn check_library_cross_compile() {
+        let ctx = TestCtx::new();
+        insta::assert_snapshot!(
+            ctx.config("check")
+                .paths(&["core", "alloc", "std"])
+                .targets(&[TEST_TRIPLE_1, TEST_TRIPLE_2])
+                .render_steps(), @r"
+        [build] llvm <host>
+        [build] rustc 0 <host> -> rustc 1 <host>
+        [check] rustc 1 <host> -> std 1 <target1>
+        [check] rustc 1 <host> -> std 1 <target2>
+        ");
+    }
+
     #[test]
     fn check_miri_no_explicit_stage() {
         let ctx = TestCtx::new();