set miri sysroots inside Cargo::new

Author: RalfJung

src/bootstrap/src/core/build_steps/test.rs

@@ -595,7 +595,7 @@ impl Step for Miri {
         // This is for the tests so everything is done with the target compiler.
         let miri_sysroot = Miri::build_miri_sysroot(builder, target_compiler, target);
         builder.ensure(compile::Std::new(target_compiler, host));
-        let sysroot = builder.sysroot(target_compiler);
+        let host_sysroot = builder.sysroot(target_compiler);
 
         // # Run `cargo test`.
         // This is with the Miri crate, so it uses the host compiler.
@@ -618,7 +618,7 @@ impl Step for Miri {
 
         // miri tests need to know about the stage sysroot
         cargo.env("MIRI_SYSROOT", &miri_sysroot);
-        cargo.env("MIRI_HOST_SYSROOT", &sysroot);
+        cargo.env("MIRI_HOST_SYSROOT", &host_sysroot);
         cargo.env("MIRI", &miri);
 
         // Set the target.
@@ -681,10 +681,6 @@ impl Step for Miri {
             }
         }
 
-        // Tell `cargo miri` where to find the sysroots.
-        cargo.env("MIRI_SYSROOT", &miri_sysroot);
-        cargo.env("MIRI_HOST_SYSROOT", sysroot);
-
         // Finally, pass test-args and run everything.
         cargo.arg("--").args(builder.config.test_args());
         let mut cargo = Command::from(cargo);

src/bootstrap/src/core/builder.rs

@@ -1235,6 +1235,7 @@ impl<'a> Builder<'a> {
         assert!(run_compiler.stage > 0, "miri can not be invoked at stage 0");
         let build_compiler = self.compiler(run_compiler.stage - 1, self.build.build);
 
+        // Prepare the tools
         let miri = self.ensure(tool::Miri {
             compiler: build_compiler,
             target: self.build.build,
@@ -1245,7 +1246,7 @@ impl<'a> Builder<'a> {
             target: self.build.build,
             extra_features: Vec::new(),
         });
-        // Invoke cargo-miri, make sure we can find miri and cargo.
+        // Invoke cargo-miri, make sure it can find miri and cargo.
         let mut cmd = Command::new(cargo_miri);
         cmd.env("MIRI", &miri);
         cmd.env("CARGO", &self.initial_cargo);
@@ -1711,6 +1712,15 @@ impl<'a> Builder<'a> {
             cargo.env("RUSTC_WRAPPER_REAL", existing_wrapper);
         }
 
+        // If this is for `miri-test`, prepare the sysroots.
+        if cmd == "miri-test" {
+            self.ensure(compile::Std::new(compiler, compiler.host));
+            let host_sysroot = self.sysroot(compiler);
+            let miri_sysroot = test::Miri::build_miri_sysroot(self, compiler, target);
+            cargo.env("MIRI_SYSROOT", &miri_sysroot);
+            cargo.env("MIRI_HOST_SYSROOT", &host_sysroot);
+        }
+
         cargo.env(profile_var("STRIP"), self.config.rust_strip.to_string());
 
         if let Some(stack_protector) = &self.config.rust_stack_protector {