enable cargo miri test doctests for stage > 0 builds

Signed-off-by: onur-ozkan <[email protected]>

Author: onur-ozkan

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

@@ -680,7 +680,16 @@ impl Step for Miri {
             .arg("--manifest-path")
             .arg(builder.src.join("src/tools/miri/test-cargo-miri/Cargo.toml"));
         cargo.arg("--target").arg(target.rustc_target_arg());
-        cargo.arg("--tests"); // don't run doctests, they are too confused by the staging
+
+        if stage == 0 {
+            builder.info("INFO: miri/test-cargo-miri doctests are ignored on stage 0.");
+            // Don't run doctests on stage0, stage0 rustdoc is incompatible with the miri sysroot
+            cargo.arg("--tests");
+        } else {
+            // Miri doesn't know which rustdoc to use by default, so tell which one it should use.
+            cargo.env("RUSTDOC_REAL", builder.rustdoc(compiler));
+        }
+
         cargo.arg("--").args(builder.config.test_args());
 
         // Tell `cargo miri` where to find things.

src/tools/miri/cargo-miri/src/phases.rs

@@ -582,8 +582,10 @@ pub fn phase_rustdoc(mut args: impl Iterator<Item = String>) {
         .map_or(0, |verbose| verbose.parse().expect("verbosity flag must be an integer"));
 
     // phase_cargo_miri sets the RUSTDOC env var to ourselves, so we can't use that here;
-    // just default to a straight-forward invocation for now:
-    let mut cmd = Command::new("rustdoc");
+    // If available, use the one provided by bootstrap; otherwise, simply default to a straightforward
+    // invocation for now:
+    let rustdoc = env::var("RUSTDOC_REAL").unwrap_or("rustdoc".to_string());
+    let mut cmd = Command::new(rustdoc);
 
     let extern_flag = "--extern";
     let runtool_flag = "--runtool";