Auto merge of #100591 - est31:stabilization_placeholder, r=Mark-Simulacrum

Require stabilizations to use a placeholder instead of writing out stabilization version

Implements the idea from [this](https://rust-lang.zulipchat.com/#narrow/stream/241545-t-release/topic/libs.20stabilization.20placeholder) zulip stream.

It's a common phenomenon that feature stabilizations don't make it into a particular release, but the version is still inaccurate. Often this is caught in the PR, but it can also require subsequent changes to adjust/correct the version. A list with examples of such PRs is given in #100577, but it's far from complete.

This PR requires stabilization PRs to use the placeholder `CURRENT_RUSTC_VERSION`, enforced via tidy tooling. The PR also adds a tool that replaces the placeholder with the version number. It can be invoked via `./x.py run src/tools/replace-version-placeholder` and is supposed to be ran upon beta branching as well as version bumping and any backports to the beta branch.  I filed PRs to the dev guide and forge to document these changes in the release and stabilization workflows:

* The [dev guide](https://rustc-dev-guide.rust-lang.org/stabilization_guide.html#determining-the-stabilization-version) PR: https://github.com/rust-lang/rustc-dev-guide/pull/1443
* The [std dev guide](https://std-dev-guide.rust-lang.org/) PR: https://github.com/rust-lang/std-dev-guide/pull/43
* The [forge](https://github.com/rust-lang/rust-forge) PR: https://github.com/rust-lang/rust-forge/pull/643

Alternative to #100577 which added checking.

1 files changed, 13 insertions, 13 deletions

diff --git a/library/std/src/backtrace.rs b/library/std/src/backtrace.rs
index 5cf6ec81789..354200d4c95 100644
--- a/library/std/src/backtrace.rs
+++ b/library/std/src/backtrace.rs
@@ -58,7 +58,7 @@
 //! `RUST_LIB_BACKTRACE` or `RUST_BACKTRACE` at runtime might not actually change
 //! how backtraces are captured.
 
-#![stable(feature = "backtrace", since = "1.65.0")]
+#![stable(feature = "backtrace", since = "CURRENT_RUSTC_VERSION")]
 
 #[cfg(test)]
 mod tests;
@@ -104,7 +104,7 @@ use crate::vec::Vec;
 /// previous point in time. In some instances the `Backtrace` type may
 /// internally be empty due to configuration. For more information see
 /// `Backtrace::capture`.
-#[stable(feature = "backtrace", since = "1.65.0")]
+#[stable(feature = "backtrace", since = "CURRENT_RUSTC_VERSION")]
 #[must_use]
 pub struct Backtrace {
     inner: Inner,
@@ -112,21 +112,21 @@ pub struct Backtrace {
 
 /// The current status of a backtrace, indicating whether it was captured or
 /// whether it is empty for some other reason.
-#[stable(feature = "backtrace", since = "1.65.0")]
+#[stable(feature = "backtrace", since = "CURRENT_RUSTC_VERSION")]
 #[non_exhaustive]
 #[derive(Debug, PartialEq, Eq)]
 pub enum BacktraceStatus {
     /// Capturing a backtrace is not supported, likely because it's not
     /// implemented for the current platform.
-    #[stable(feature = "backtrace", since = "1.65.0")]
+    #[stable(feature = "backtrace", since = "CURRENT_RUSTC_VERSION")]
     Unsupported,
     /// Capturing a backtrace has been disabled through either the
     /// `RUST_LIB_BACKTRACE` or `RUST_BACKTRACE` environment variables.
-    #[stable(feature = "backtrace", since = "1.65.0")]
+    #[stable(feature = "backtrace", since = "CURRENT_RUSTC_VERSION")]
     Disabled,
     /// A backtrace has been captured and the `Backtrace` should print
     /// reasonable information when rendered.
-    #[stable(feature = "backtrace", since = "1.65.0")]
+    #[stable(feature = "backtrace", since = "CURRENT_RUSTC_VERSION")]
     Captured,
 }
 
@@ -173,7 +173,7 @@ enum BytesOrWide {
     Wide(Vec<u16>),
 }
 
-#[stable(feature = "backtrace", since = "1.65.0")]
+#[stable(feature = "backtrace", since = "CURRENT_RUSTC_VERSION")]
 impl fmt::Debug for Backtrace {
     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
         let capture = match &self.inner {
@@ -289,7 +289,7 @@ impl Backtrace {
     ///
     /// To forcibly capture a backtrace regardless of environment variables, use
     /// the `Backtrace::force_capture` function.
-    #[stable(feature = "backtrace", since = "1.65.0")]
+    #[stable(feature = "backtrace", since = "CURRENT_RUSTC_VERSION")]
     #[inline(never)] // want to make sure there's a frame here to remove
     pub fn capture() -> Backtrace {
         if !Backtrace::enabled() {
@@ -308,7 +308,7 @@ impl Backtrace {
     /// Note that capturing a backtrace can be an expensive operation on some
     /// platforms, so this should be used with caution in performance-sensitive
     /// parts of code.
-    #[stable(feature = "backtrace", since = "1.65.0")]
+    #[stable(feature = "backtrace", since = "CURRENT_RUSTC_VERSION")]
     #[inline(never)] // want to make sure there's a frame here to remove
     pub fn force_capture() -> Backtrace {
         Backtrace::create(Backtrace::force_capture as usize)
@@ -316,8 +316,8 @@ impl Backtrace {
 
     /// Forcibly captures a disabled backtrace, regardless of environment
     /// variable configuration.
-    #[stable(feature = "backtrace", since = "1.65.0")]
-    #[rustc_const_stable(feature = "backtrace", since = "1.65.0")]
+    #[stable(feature = "backtrace", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "backtrace", since = "CURRENT_RUSTC_VERSION")]
     pub const fn disabled() -> Backtrace {
         Backtrace { inner: Inner::Disabled }
     }
@@ -361,7 +361,7 @@ impl Backtrace {
     /// Returns the status of this backtrace, indicating whether this backtrace
     /// request was unsupported, disabled, or a stack trace was actually
     /// captured.
-    #[stable(feature = "backtrace", since = "1.65.0")]
+    #[stable(feature = "backtrace", since = "CURRENT_RUSTC_VERSION")]
     #[must_use]
     pub fn status(&self) -> BacktraceStatus {
         match self.inner {
@@ -381,7 +381,7 @@ impl<'a> Backtrace {
     }
 }
 
-#[stable(feature = "backtrace", since = "1.65.0")]
+#[stable(feature = "backtrace", since = "CURRENT_RUSTC_VERSION")]
 impl fmt::Display for Backtrace {
     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
         let capture = match &self.inner {