enable `rust_2018_idioms` for doctests

Signed-off-by: ozkanonur <work@onurozkan.dev>

2 files changed, 9 insertions, 0 deletions

diff --git a/src/bootstrap/builder.rs b/src/bootstrap/builder.rs
index 0d2d512b4b2..e9c91ef0676 100644
--- a/src/bootstrap/builder.rs
+++ b/src/bootstrap/builder.rs
@@ -2146,6 +2146,10 @@ impl<'a> Builder<'a> {
 #[cfg(test)]
 mod tests;
 
+/// Represents flag values in `String` form with whitespace delimiter to pass it to the compiler later.
+///
+/// `-Z crate-attr` flags will be applied recursively on the target code using the `rustc_parse::parser::Parser`.
+/// See `rustc_builtin_macros::cmdline_attrs::inject` for more information.
 #[derive(Debug, Clone)]
 struct Rustflags(String, TargetSelection);
 
diff --git a/src/bootstrap/compile.rs b/src/bootstrap/compile.rs
index 7d2a6862500..1de9f592a27 100644
--- a/src/bootstrap/compile.rs
+++ b/src/bootstrap/compile.rs
@@ -412,6 +412,8 @@ pub fn std_cargo(builder: &Builder<'_>, target: TargetSelection, stage: u32, car
         format!("-Zcrate-attr=doc(html_root_url=\"{}/\")", builder.doc_rust_lang_org_channel(),);
     cargo.rustflag(&html_root);
     cargo.rustdocflag(&html_root);
+
+    cargo.rustdocflag("-Zcrate-attr=warn(rust_2018_idioms)");
 }
 
 #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
@@ -810,6 +812,9 @@ pub fn rustc_cargo(builder: &Builder<'_>, cargo: &mut Cargo, target: TargetSelec
         .arg(builder.rustc_features(builder.kind))
         .arg("--manifest-path")
         .arg(builder.src.join("compiler/rustc/Cargo.toml"));
+
+    cargo.rustdocflag("-Zcrate-attr=warn(rust_2018_idioms)");
+
     rustc_cargo_env(builder, cargo, target, stage);
 }