add no_std support

Cargo.toml

@@ -15,7 +15,7 @@ rust-version = "1.65.0"
 
 [workspace.dependencies]
 indenter = "0.3.0"
-once_cell = "1.18.0"
+once_cell = { version = "1.18.0", default-features = false }
 owo-colors = "4.0"
 autocfg = "1.0"
 

eyre/Cargo.toml

@@ -13,14 +13,18 @@ readme = { workspace = true }
 rust-version = { workspace = true }
 
 [features]
-default = ["anyhow", "auto-install", "track-caller"]
+default = ["anyhow", "auto-install", "std", "track-caller"]
 anyhow = []
 auto-install = []
+std = []
 track-caller = []
 
 [dependencies]
 indenter = { workspace = true }
-once_cell = { workspace = true }
+once_cell = { workspace = true, default-features = false, features = [
+  "alloc",
+  "race",
+] }
 pyo3 = { version = "0.24.0", optional = true, default-features = false }
 
 [build-dependencies]

eyre/build.rs

@@ -23,7 +23,9 @@ fn main() {
     }
 
     // https://github.com/rust-lang/rust/issues/47809 [rustc-1.46]
-    ac.emit_expression_cfg("std::panic::Location::caller", "track_caller");
+    if ac.probe_rustc_version(1, 46) {
+        autocfg::emit("track_caller");
+    }
 
     if ac.probe_rustc_version(1, 52) {
         autocfg::emit("eyre_no_fmt_arguments_as_str");
@@ -33,6 +35,7 @@ fn main() {
         autocfg::emit("eyre_no_fmt_args_capture");
     }
 
+    #[cfg(feature = "std")]
     if ac.probe_rustc_version(1, 65) {
         autocfg::emit("backtrace")
     }

eyre/src/backtrace.rs

@@ -18,7 +18,7 @@ macro_rules! capture_backtrace {
     };
 }
 /// Capture a backtrace iff there is not already a backtrace in the error chain
-#[cfg(generic_member_access)]
+#[cfg(all(generic_member_access, backtrace))]
 macro_rules! backtrace_if_absent {
     ($err:expr) => {
         match std::error::request_ref::<std::backtrace::Backtrace>($err as &dyn std::error::Error) {
@@ -28,7 +28,7 @@ macro_rules! backtrace_if_absent {
     };
 }
 
-#[cfg(not(generic_member_access))]
+#[cfg(not(all(generic_member_access, backtrace)))]
 macro_rules! backtrace_if_absent {
     ($err:expr) => {
         capture_backtrace!()

eyre/src/chain.rs

@@ -1,7 +1,7 @@
 use self::ChainState::*;
 use crate::StdError;
 
-use std::vec;
+use alloc::vec::{self, Vec};
 
 pub(crate) use crate::Chain;
 

eyre/src/context.rs

@@ -14,7 +14,7 @@ mod ext {
 
     impl<E> StdError for E
     where
-        E: std::error::Error + Send + Sync + 'static,
+        E: core::error::Error + Send + Sync + 'static,
     {
         fn ext_report<D>(self, msg: D) -> Report
         where
@@ -137,7 +137,7 @@ where
     E: StdError + 'static,
 {
     #[cfg(generic_member_access)]
-    fn provide<'a>(&'a self, request: &mut std::error::Request<'a>) {
+    fn provide<'a>(&'a self, request: &mut core::error::Request<'a>) {
         self.error.provide(request);
     }
 

eyre/src/error.rs

@@ -2,6 +2,7 @@ use crate::chain::Chain;
 use crate::ptr::{MutPtr, OwnedPtr, RefPtr};
 use crate::EyreHandler;
 use crate::{Report, StdError};
+use alloc::boxed::Box;
 use core::any::TypeId;
 use core::fmt::{self, Debug, Display};
 use core::mem::{self, ManuallyDrop};
@@ -856,7 +857,7 @@ where
     E: StdError,
 {
     #[cfg(generic_member_access)]
-    fn provide<'a>(&'a self, request: &mut std::error::Request<'a>) {
+    fn provide<'a>(&'a self, request: &mut core::error::Request<'a>) {
         self._object.provide(request)
     }
 

eyre/src/kind.rs

@@ -46,6 +46,7 @@
 //     (&error).eyre_kind().new(error)
 
 use crate::Report;
+use alloc::boxed::Box;
 use core::fmt::{Debug, Display};
 
 use crate::StdError;

eyre/src/lib.rs

@@ -362,6 +362,7 @@
     clippy::new_ret_no_self,
     clippy::wrong_self_convention
 )]
+#![cfg_attr(not(feature = "std"), no_std)]
 
 extern crate alloc;
 
@@ -381,13 +382,14 @@ use crate::backtrace::Backtrace;
 use crate::error::ErrorImpl;
 use core::fmt::{Debug, Display};
 
-use std::error::Error as StdError;
+use core::error::Error as StdError;
 
+use alloc::boxed::Box;
 pub use eyre as format_err;
 /// Compatibility re-export of `eyre` for interop with `anyhow`
 #[cfg(feature = "anyhow")]
 pub use eyre as anyhow;
-use once_cell::sync::OnceCell;
+use once_cell::race::OnceBox;
 use ptr::OwnedPtr;
 #[cfg(feature = "anyhow")]
 #[doc(hidden)]
@@ -485,7 +487,7 @@ pub struct Report {
 type ErrorHook =
     Box<dyn Fn(&(dyn StdError + 'static)) -> Box<dyn EyreHandler> + Sync + Send + 'static>;
 
-static HOOK: OnceCell<ErrorHook> = OnceCell::new();
+static HOOK: OnceBox<ErrorHook> = OnceBox::new();
 
 /// Error indicating that `set_hook` was unable to install the provided ErrorHook
 #[derive(Debug, Clone, Copy)]
@@ -596,7 +598,7 @@ impl StdError for InstallError {}
 /// }
 /// ```
 pub fn set_hook(hook: ErrorHook) -> Result<(), InstallError> {
-    HOOK.set(hook).map_err(|_| InstallError)
+    HOOK.set(Box::new(hook)).map_err(|_| InstallError)
 }
 
 #[cfg_attr(track_caller, track_caller)]
@@ -610,14 +612,14 @@ fn capture_handler(error: &(dyn StdError + 'static)) -> Box<dyn EyreHandler> {
 
     #[cfg(feature = "auto-install")]
     let hook = HOOK
-        .get_or_init(|| Box::new(DefaultHandler::default_with))
+        .get_or_init(|| Box::new(Box::new(DefaultHandler::default_with)))
         .as_ref();
 
     let mut handler = hook(error);
 
     #[cfg(track_caller)]
     {
-        handler.track_caller(std::panic::Location::caller())
+        handler.track_caller(core::panic::Location::caller())
     }
 
     handler
@@ -734,7 +736,7 @@ pub trait EyreHandler: core::any::Any + Send + Sync {
 
     /// Store the location of the caller who constructed this error report
     #[allow(unused_variables)]
-    fn track_caller(&mut self, location: &'static std::panic::Location<'static>) {}
+    fn track_caller(&mut self, location: &'static core::panic::Location<'static>) {}
 }
 
 /// The default provided error report handler for `eyre::Report`.
@@ -745,7 +747,7 @@ pub trait EyreHandler: core::any::Any + Send + Sync {
 pub struct DefaultHandler {
     backtrace: Option<Backtrace>,
     #[cfg(track_caller)]
-    location: Option<&'static std::panic::Location<'static>>,
+    location: Option<&'static core::panic::Location<'static>>,
 }
 
 impl DefaultHandler {
@@ -838,7 +840,7 @@ impl EyreHandler for DefaultHandler {
             }
         }
 
-        #[cfg(generic_member_access)]
+        #[cfg(all(generic_member_access, backtrace))]
         {
             use std::backtrace::BacktraceStatus;
 
@@ -860,7 +862,7 @@ impl EyreHandler for DefaultHandler {
     }
 
     #[cfg(track_caller)]
-    fn track_caller(&mut self, location: &'static std::panic::Location<'static>) {
+    fn track_caller(&mut self, location: &'static core::panic::Location<'static>) {
         self.location = Some(location);
     }
 }

eyre/src/ptr.rs

@@ -1,4 +1,6 @@
-use std::{marker::PhantomData, ptr::NonNull};
+use core::{marker::PhantomData, ptr::NonNull};
+
+use alloc::boxed::Box;
 
 /// An owned pointer
 ///

eyre/src/wrapper.rs

@@ -1,4 +1,5 @@
 use crate::StdError;
+use alloc::boxed::Box;
 use core::fmt::{self, Debug, Display};
 
 #[repr(transparent)]
@@ -83,7 +84,7 @@ impl Display for BoxedError {
 
 impl StdError for BoxedError {
     #[cfg(generic_member_access)]
-    fn provide<'a>(&'a self, request: &mut std::error::Request<'a>) {
+    fn provide<'a>(&'a self, request: &mut core::error::Request<'a>) {
         self.0.provide(request);
     }