Auto merge of #101928 - notriddle:rollup-pexhhxe, r=notriddle

Rollup of 8 pull requests

Successful merges:

 - #101340 (Adding Fuchsia zxdb debugging walkthrough to docs)
 - #101741 (Adding needs-unwind arg to applicable compiler ui tests)
 - #101782 (Update `symbol_mangling` diagnostics migration)
 - #101878 (More simple formatting)
 - #101898 (Remove some unused CSS rules)
 - #101911 (rustdoc: remove no-op CSS on `.source .content`)
 - #101914 (rustdoc-json-types: Document that ResolvedPath can also be a union)
 - #101921 (Pass --cfg=bootstrap for rustdoc for proc_macro crates)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

2 files changed, 13 insertions, 4 deletions

diff --git a/src/bootstrap/bin/rustc.rs b/src/bootstrap/bin/rustc.rs
index bd5790d2ea8..e96f8b0d312 100644
--- a/src/bootstrap/bin/rustc.rs
+++ b/src/bootstrap/bin/rustc.rs
@@ -139,10 +139,8 @@ fn main() {
         // Cargo doesn't pass RUSTFLAGS to proc_macros:
         // https://github.com/rust-lang/cargo/issues/4423
         // Thus, if we are on stage 0, we explicitly set `--cfg=bootstrap`.
-        // We also declare that the flag is expected, which is mainly needed for
-        // later stages so that they don't warn about #[cfg(bootstrap)],
-        // but enabling it for stage 0 too lets any warnings, if they occur,
-        // occur more early on, e.g. about #[cfg(bootstrap = "foo")].
+        // We also declare that the flag is expected, which we need to do to not
+        // get warnings about it being unexpected.
         if stage == "0" {
             cmd.arg("--cfg=bootstrap");
         }
diff --git a/src/bootstrap/bin/rustdoc.rs b/src/bootstrap/bin/rustdoc.rs
index 87c1d22e771..e69cab956c5 100644
--- a/src/bootstrap/bin/rustdoc.rs
+++ b/src/bootstrap/bin/rustdoc.rs
@@ -11,6 +11,7 @@ include!("../dylib_util.rs");
 
 fn main() {
     let args = env::args_os().skip(1).collect::<Vec<_>>();
+    let stage = env::var("RUSTC_STAGE").expect("RUSTC_STAGE was not set");
     let rustdoc = env::var_os("RUSTDOC_REAL").expect("RUSTDOC_REAL was not set");
     let libdir = env::var_os("RUSTDOC_LIBDIR").expect("RUSTDOC_LIBDIR was not set");
     let sysroot = env::var_os("RUSTC_SYSROOT").expect("RUSTC_SYSROOT was not set");
@@ -62,6 +63,16 @@ fn main() {
             cmd.arg("-Clink-arg=-Wl,--threads=1");
         }
     }
+    // Cargo doesn't pass RUSTDOCFLAGS to proc_macros:
+    // https://github.com/rust-lang/cargo/issues/4423
+    // Thus, if we are on stage 0, we explicitly set `--cfg=bootstrap`.
+    // We also declare that the flag is expected, which we need to do to not
+    // get warnings about it being unexpected.
+    if stage == "0" {
+        cmd.arg("--cfg=bootstrap");
+    }
+    cmd.arg("-Zunstable-options");
+    cmd.arg("--check-cfg=values(bootstrap)");
 
     if verbose > 1 {
         eprintln!(