Allow adding `RUSTFLAGS` after `Builder::cargo`

This commit changes the return type of `Builder::cargo` to return a
builder that allows dynamically adding more `RUSTFLAGS` values
after-the-fact. While not used yet, this will later be used to delete
more of `rustc.rs`

1 files changed, 3 insertions, 3 deletions

diff --git a/src/bootstrap/doc.rs b/src/bootstrap/doc.rs
index 873a3c31d15..4ee8cd2485c 100644
--- a/src/bootstrap/doc.rs
+++ b/src/bootstrap/doc.rs
@@ -475,7 +475,7 @@ impl Step for Std {
                  .arg("--resource-suffix").arg(crate::channel::CFG_RELEASE_NUM)
                  .arg("--index-page").arg(&builder.src.join("src/doc/index.md"));
 
-            builder.run(&mut cargo);
+            builder.run(&mut cargo.into());
         };
         for krate in &["alloc", "core", "std", "proc_macro", "test"] {
             run_cargo_rustdoc_for(krate);
@@ -561,7 +561,7 @@ impl Step for Rustc {
             cargo.arg("-p").arg(krate);
         }
 
-        builder.run(&mut cargo);
+        builder.run(&mut cargo.into());
     }
 }
 
@@ -656,7 +656,7 @@ impl Step for Rustdoc {
         cargo.arg("-p").arg("rustdoc");
 
         cargo.env("RUSTDOCFLAGS", "--document-private-items");
-        builder.run(&mut cargo);
+        builder.run(&mut cargo.into());
     }
 }