8 files changed, 66 insertions, 8 deletions
diff --git a/compiler/rustc_data_structures/src/flock.rs b/compiler/rustc_data_structures/src/flock.rs
index f33f6b7cac1..60ae7ad115a 100644
--- a/compiler/rustc_data_structures/src/flock.rs
+++ b/compiler/rustc_data_structures/src/flock.rs
@@ -4,7 +4,18 @@
 //! green/native threading. This is just a bare-bones enough solution for
 //! librustdoc, it is not production quality at all.
 
-cfg_select! {
+// cfg(bootstrap)
+macro_rules! cfg_select_dispatch {
+    ($($tokens:tt)*) => {
+        #[cfg(bootstrap)]
+        cfg_match! { $($tokens)* }
+
+        #[cfg(not(bootstrap))]
+        cfg_select! { $($tokens)* }
+    };
+}
+
+cfg_select_dispatch! {
     target_os = "linux" => {
         mod linux;
         use linux as imp;
diff --git a/compiler/rustc_data_structures/src/lib.rs b/compiler/rustc_data_structures/src/lib.rs
index b34a7fdb9e4..b7447e24731 100644
--- a/compiler/rustc_data_structures/src/lib.rs
+++ b/compiler/rustc_data_structures/src/lib.rs
@@ -10,6 +10,8 @@
 #![allow(internal_features)]
 #![allow(rustc::default_hash_types)]
 #![allow(rustc::potential_query_instability)]
+#![cfg_attr(bootstrap, feature(cfg_match))]
+#![cfg_attr(not(bootstrap), feature(cfg_select))]
 #![deny(unsafe_op_in_unsafe_fn)]
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![doc(rust_logo)]
@@ -19,7 +21,6 @@
 #![feature(ascii_char_variants)]
 #![feature(assert_matches)]
 #![feature(auto_traits)]
-#![feature(cfg_select)]
 #![feature(core_intrinsics)]
 #![feature(dropck_eyepatch)]
 #![feature(extend_one)]
diff --git a/compiler/rustc_data_structures/src/profiling.rs b/compiler/rustc_data_structures/src/profiling.rs
index 36649a36070..e3a01e4035c 100644
--- a/compiler/rustc_data_structures/src/profiling.rs
+++ b/compiler/rustc_data_structures/src/profiling.rs
@@ -859,8 +859,19 @@ fn get_thread_id() -> u32 {
     std::thread::current().id().as_u64().get() as u32
 }
 
+// cfg(bootstrap)
+macro_rules! cfg_select_dispatch {
+    ($($tokens:tt)*) => {
+        #[cfg(bootstrap)]
+        cfg_match! { $($tokens)* }
+
+        #[cfg(not(bootstrap))]
+        cfg_select! { $($tokens)* }
+    };
+}
+
 // Memory reporting
-cfg_select! {
+cfg_select_dispatch! {
     windows => {
         pub fn get_resident_set_size() -> Option<usize> {
             use windows::{
diff --git a/compiler/rustc_span/src/analyze_source_file.rs b/compiler/rustc_span/src/analyze_source_file.rs
index c32593a6d95..55d899c9ada 100644
--- a/compiler/rustc_span/src/analyze_source_file.rs
+++ b/compiler/rustc_span/src/analyze_source_file.rs
@@ -29,7 +29,18 @@ pub(crate) fn analyze_source_file(src: &str) -> (Vec<RelativeBytePos>, Vec<Multi
     (lines, multi_byte_chars)
 }
 
-cfg_select! {
+// cfg(bootstrap)
+macro_rules! cfg_select_dispatch {
+    ($($tokens:tt)*) => {
+        #[cfg(bootstrap)]
+        cfg_match! { $($tokens)* }
+
+        #[cfg(not(bootstrap))]
+        cfg_select! { $($tokens)* }
+    };
+}
+
+cfg_select_dispatch! {
     any(target_arch = "x86", target_arch = "x86_64") => {
         fn analyze_source_file_dispatch(
             src: &str,
diff --git a/compiler/rustc_span/src/lib.rs b/compiler/rustc_span/src/lib.rs
index 906462a0d22..e950493f135 100644
--- a/compiler/rustc_span/src/lib.rs
+++ b/compiler/rustc_span/src/lib.rs
@@ -17,10 +17,11 @@
 
 // tidy-alphabetical-start
 #![allow(internal_features)]
+#![cfg_attr(bootstrap, feature(cfg_match))]
+#![cfg_attr(not(bootstrap), feature(cfg_select))]
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![doc(rust_logo)]
 #![feature(array_windows)]
-#![feature(cfg_select)]
 #![feature(core_io_borrowed_buf)]
 #![feature(hash_set_entry)]
 #![feature(if_let_guard)]
diff --git a/src/tools/miri/src/concurrency/mod.rs b/src/tools/miri/src/concurrency/mod.rs
index 17d0f3f5ff6..aaa3fc85a6c 100644
--- a/src/tools/miri/src/concurrency/mod.rs
+++ b/src/tools/miri/src/concurrency/mod.rs
@@ -8,8 +8,19 @@ pub mod thread;
 mod vector_clock;
 pub mod weak_memory;
 
+// cfg(bootstrap)
+macro_rules! cfg_select_dispatch {
+    ($($tokens:tt)*) => {
+        #[cfg(bootstrap)]
+        cfg_match! { $($tokens)* }
+
+        #[cfg(not(bootstrap))]
+        cfg_select! { $($tokens)* }
+    };
+}
+
 // Import either the real genmc adapter or a dummy module.
-cfg_select! {
+cfg_select_dispatch! {
     feature = "genmc" => {
         mod genmc;
         pub use self::genmc::{GenmcCtx, GenmcConfig};
diff --git a/src/tools/miri/src/lib.rs b/src/tools/miri/src/lib.rs
index 9d663ca9edf..a3d2b8c874e 100644
--- a/src/tools/miri/src/lib.rs
+++ b/src/tools/miri/src/lib.rs
@@ -1,5 +1,6 @@
+#![cfg_attr(bootstrap, feature(cfg_match))]
+#![cfg_attr(not(bootstrap), feature(cfg_select))]
 #![feature(rustc_private)]
-#![feature(cfg_select)]
 #![feature(float_gamma)]
 #![feature(float_erf)]
 #![feature(map_try_insert)]
diff --git a/src/tools/miri/src/shims/unix/fs.rs b/src/tools/miri/src/shims/unix/fs.rs
index 347930c52f2..31cb269059c 100644
--- a/src/tools/miri/src/shims/unix/fs.rs
+++ b/src/tools/miri/src/shims/unix/fs.rs
@@ -89,8 +89,19 @@ impl UnixFileDescription for FileHandle {
         communicate_allowed: bool,
         op: FlockOp,
     ) -> InterpResult<'tcx, io::Result<()>> {
+        // cfg(bootstrap)
+        macro_rules! cfg_select_dispatch {
+            ($($tokens:tt)*) => {
+                #[cfg(bootstrap)]
+                cfg_match! { $($tokens)* }
+
+                #[cfg(not(bootstrap))]
+                cfg_select! { $($tokens)* }
+            };
+        }
+
         assert!(communicate_allowed, "isolation should have prevented even opening a file");
-        cfg_select! {
+        cfg_select_dispatch! {
             all(target_family = "unix", not(target_os = "solaris")) => {
                 use std::os::fd::AsRawFd;