Stabilize the backtrace feature.

compiler/rustc_errors/src/lib.rs

@@ -4,7 +4,6 @@
 
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![feature(crate_visibility_modifier)]
-#![feature(backtrace)]
 #![feature(nll)]
 
 #[macro_use]

compiler/rustc_middle/src/lib.rs

@@ -25,7 +25,6 @@
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![feature(array_windows)]
 #![feature(assoc_char_funcs)]
-#![feature(backtrace)]
 #![feature(bool_to_option)]
 #![feature(box_patterns)]
 #![feature(box_syntax)]

library/std/src/backtrace.rs

@@ -9,12 +9,6 @@
 //! implementing `std::error::Error`) to get a causal chain of where an error
 //! was generated.
 //!
-//! > **Note**: this module is unstable and is designed in [RFC 2504], and you
-//! > can learn more about its status in the [tracking issue].
-//!
-//! [RFC 2504]: https://github.com/rust-lang/rfcs/blob/master/text/2504-fix-error.md
-//! [tracking issue]: https://github.com/rust-lang/rust/issues/53487
-//!
 //! ## Accuracy
 //!
 //! Backtraces are attempted to be as accurate as possible, but no guarantees
@@ -64,7 +58,7 @@
 //! `RUST_LIB_BACKTRACE` or `RUST_BACKTRACE` at runtime may not actually change
 //! how backtraces are captured.
 
-#![unstable(feature = "backtrace", issue = "53487")]
+#![stable(feature = "backtrace", since = "1.51.0")]
 
 #[cfg(test)]
 mod tests;
@@ -109,6 +103,7 @@ 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 = "1.51.0")]
 pub struct Backtrace {
     inner: Inner,
 }
@@ -117,15 +112,19 @@ pub struct Backtrace {
 /// whether it is empty for some other reason.
 #[non_exhaustive]
 #[derive(Debug, PartialEq, Eq)]
+#[stable(feature = "backtrace", since = "1.51.0")]
 pub enum BacktraceStatus {
     /// Capturing a backtrace is not supported, likely because it's not
     /// implemented for the current platform.
+    #[stable(feature = "backtrace", since = "1.51.0")]
     Unsupported,
     /// Capturing a backtrace has been disabled through either the
     /// `RUST_LIB_BACKTRACE` or `RUST_BACKTRACE` environment variables.
+    #[stable(feature = "backtrace", since = "1.51.0")]
     Disabled,
     /// A backtrace has been captured and the `Backtrace` should print
     /// reasonable information when rendered.
+    #[stable(feature = "backtrace", since = "1.51.0")]
     Captured,
 }
 
@@ -169,6 +168,7 @@ enum BytesOrWide {
     Wide(Vec<u16>),
 }
 
+#[stable(feature = "backtrace", since = "1.51.0")]
 impl fmt::Debug for Backtrace {
     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
         let mut capture = match &self.inner {
@@ -276,6 +276,7 @@ impl Backtrace {
     ///
     /// To forcibly capture a backtrace regardless of environment variables, use
     /// the `Backtrace::force_capture` function.
+    #[stable(feature = "backtrace", since = "1.51.0")]
     #[inline(never)] // want to make sure there's a frame here to remove
     pub fn capture() -> Backtrace {
         if !Backtrace::enabled() {
@@ -294,13 +295,16 @@ 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 = "1.51.0")]
     #[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)
     }
 
     /// Forcibly captures a disabled backtrace, regardless of environment
     /// variable configuration.
+    #[stable(feature = "backtrace", since = "1.51.0")]
+    #[rustc_const_stable(feature = "const_backtrace_disabled", since = "1.51.0")]
     pub const fn disabled() -> Backtrace {
         Backtrace { inner: Inner::Disabled }
     }
@@ -344,6 +348,7 @@ 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 = "1.51.0")]
     pub fn status(&self) -> BacktraceStatus {
         match self.inner {
             Inner::Unsupported => BacktraceStatus::Unsupported,
@@ -353,6 +358,7 @@ impl Backtrace {
     }
 }
 
+#[stable(feature = "backtrace", since = "1.51.0")]
 impl fmt::Display for Backtrace {
     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
         let mut capture = match &self.inner {

library/std/src/error.rs

@@ -122,7 +122,7 @@ pub trait Error: Debug + Display {
     /// Note that not all errors contain a `Backtrace`. Also note that a
     /// `Backtrace` may actually be empty. For more information consult the
     /// `Backtrace` type itself.
-    #[unstable(feature = "backtrace", issue = "53487")]
+    #[stable(feature = "backtrace", since = "1.51.0")]
     fn backtrace(&self) -> Option<&Backtrace> {
         None
     }

src/test/ui/std-backtrace.rs

@@ -6,8 +6,6 @@
 // ignore-msvc see #62897 and `backtrace-debuginfo.rs` test
 // compile-flags:-g
 
-#![feature(backtrace)]
-
 use std::env;
 use std::process::Command;
 use std::str;