From 1ae4a0cc3487f28b29f36afe8056535afad21e7b Mon Sep 17 00:00:00 2001
From: Josh Triplett <josh@joshtriplett.org>
Date: Sun, 10 Aug 2025 14:25:43 -0700
Subject: library: Migrate from `cfg_if` to `cfg_select`

Migrate the standard library from using the external `cfg_if` crate to
using the now-built-in `cfg_select` macro.

This does not yet eliminate the dependency from
`library/std/Cargo.toml`, because while the standard library itself no
longer uses `cfg_if`, it also incorporates the `backtrace` crate, which
does.

Migration assisted by the following vim command (after selecting the
full `cfg_if!` invocation):

```
'<,'>s/\(cfg_if::\)\?cfg_if/cfg_select/ | '<,'>s/^\( *\)} else {/\1}\r\1_ => {/c | '<,'>s/^\( *\)} else if #\[cfg(\(.*\))\] /\1}\r\1\2 => /e | '<,'>s/if #\[cfg(\(.*\))\] {/\1 => {/e
```

This is imperfect, but substantially accelerated the process. This
prompts for confirmation on the `} else {` since that can also appear
inside one of the arms. This also requires manual intervention to handle
any multi-line conditions.
---
 library/std/src/thread/current.rs | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

(limited to 'library/std/src/thread/current.rs')

diff --git a/library/std/src/thread/current.rs b/library/std/src/thread/current.rs
index 5c879903526..7da1621da45 100644
--- a/library/std/src/thread/current.rs
+++ b/library/std/src/thread/current.rs
@@ -18,8 +18,8 @@ local_pointer! {
 pub(super) mod id {
     use super::*;
 
-    cfg_if::cfg_if! {
-        if #[cfg(target_thread_local)] {
+    cfg_select! {
+        target_thread_local => {
             use crate::cell::Cell;
 
             #[thread_local]
@@ -34,7 +34,8 @@ pub(super) mod id {
             pub(super) fn set(id: ThreadId) {
                 ID.set(Some(id))
             }
-        } else if #[cfg(target_pointer_width = "16")] {
+        }
+        target_pointer_width = "16" => {
             local_pointer! {
                 static ID0;
                 static ID16;
@@ -59,7 +60,8 @@ pub(super) mod id {
                 ID32.set(ptr::without_provenance_mut((val >> 32) as usize));
                 ID48.set(ptr::without_provenance_mut((val >> 48) as usize));
             }
-        } else if #[cfg(target_pointer_width = "32")] {
+        }
+        target_pointer_width = "32" => {
             local_pointer! {
                 static ID0;
                 static ID32;
@@ -78,7 +80,8 @@ pub(super) mod id {
                 ID0.set(ptr::without_provenance_mut(val as usize));
                 ID32.set(ptr::without_provenance_mut((val >> 32) as usize));
             }
-        } else {
+        }
+        _ => {
             local_pointer! {
                 static ID;
             }
-- 
cgit 1.4.1-3-g733a5