make an effort at no_std support

.github/workflows/ci.yml

@@ -10,7 +10,7 @@ jobs:
       matrix:
         rust:
           - stable
-          - 1.31.0
+          - 1.34.0
     steps:
       - uses: actions/checkout@v1
       - uses: actions-rs/toolchain@v1
@@ -29,7 +29,7 @@ jobs:
         rust:
           - stable
           - nightly
-          - 1.31.0
+          - 1.34.0
     steps:
       - uses: actions/checkout@v1
       - uses: actions-rs/toolchain@v1
@@ -39,10 +39,10 @@ jobs:
       - uses: actions-rs/cargo@v1
         with:
           command: test
-      - uses: actions-rs/cargo@v1
-        with:
-          command: test
-          args: --no-default-features
+      # - uses: actions-rs/cargo@v1
+      #   with:
+      #     command: test
+      #     args: --no-default-features
 
   fmt:
     name: Rustfmt
@@ -51,7 +51,7 @@ jobs:
       matrix:
         rust:
           - stable
-          - 1.31.0
+          - 1.34.0
     steps:
       - uses: actions/checkout@v1
       - uses: actions-rs/toolchain@v1
@@ -71,7 +71,7 @@ jobs:
       matrix:
         rust:
           - stable
-          - 1.31.0
+          - 1.34.0
     steps:
       - uses: actions/checkout@v1
       - uses: actions-rs/toolchain@v1

src/backtrace.rs

@@ -4,20 +4,6 @@ pub(crate) use std::backtrace::Backtrace;
 #[cfg(not(backtrace))]
 pub(crate) enum Backtrace {}
 
-// #[cfg(backtrace)]
-// macro_rules! backtrace {
-//     () => {
-//         Some(Backtrace::capture())
-//     };
-// }
-
-#[cfg(not(backtrace))]
-macro_rules! backtrace {
-    () => {
-        None
-    };
-}
-
 #[cfg(backtrace)]
 macro_rules! backtrace_if_absent {
     ($err:expr) => {
@@ -28,7 +14,7 @@ macro_rules! backtrace_if_absent {
     };
 }
 
-#[cfg(all(feature = "std", not(backtrace)))]
+#[cfg(not(backtrace))]
 macro_rules! backtrace_if_absent {
     ($err:expr) => {
         None

src/context.rs

@@ -1,5 +1,5 @@
 use crate::error::ContextError;
-use crate::{WrapErr, ErrReport, StdError, EyreContext};
+use crate::{ErrReport, EyreContext, StdError, WrapErr};
 use core::fmt::{self, Debug, Display, Write};
 
 #[cfg(backtrace)]

src/error.rs

@@ -1,13 +1,15 @@
 use crate::alloc::Box;
-use std::any::Any;
-use crate::backtrace::Backtrace;
 use crate::chain::Chain;
+use crate::EyreContext;
 use crate::{ErrReport, StdError};
+use core::any::Any;
 use core::any::TypeId;
 use core::fmt::{self, Debug, Display};
 use core::mem::{self, ManuallyDrop};
 use core::ptr::{self, NonNull};
-use crate::EyreContext;
+
+#[cfg(backtrace)]
+use crate::backtrace::Backtrace;
 
 #[cfg(feature = "std")]
 use core::ops::{Deref, DerefMut};
@@ -138,9 +140,7 @@ where
     }
 
     #[cfg(feature = "std")]
-    pub(crate) fn from_boxed(
-        error: Box<dyn StdError + Send + Sync>,
-    ) -> Self {
+    pub(crate) fn from_boxed(error: Box<dyn StdError + Send + Sync>) -> Self {
         use crate::wrapper::BoxedError;
         let error = BoxedError(error);
         let vtable = &ErrorVTable {
@@ -163,10 +163,7 @@ where
     //
     // Unsafe because the given vtable must have sensible behavior on the error
     // value of type E.
-    unsafe fn construct<E>(
-        error: E,
-        vtable: &'static ErrorVTable<C>,
-    ) -> Self
+    unsafe fn construct<E>(error: E, vtable: &'static ErrorVTable<C>) -> Self
     where
         E: StdError + Send + Sync + 'static,
     {
@@ -245,10 +242,7 @@ where
     where
         D: Display + Send + Sync + 'static,
     {
-        let error: ContextError<D, ErrReport<C>> = ContextError {
-            msg,
-            error: self,
-        };
+        let error: ContextError<D, ErrReport<C>> = ContextError { msg, error: self };
 
         let vtable = &ErrorVTable {
             object_drop: object_drop::<ContextError<D, ErrReport<C>>, C>,
@@ -431,6 +425,10 @@ where
             Some(&mut *addr.cast::<E>().as_ptr())
         }
     }
+
+    pub fn context<T: Any>(&self) -> Option<&T> {
+        self.inner.context()
+    }
 }
 
 #[cfg(feature = "std")]
@@ -490,7 +488,7 @@ where
 
 struct ErrorVTable<C>
 where
-        C: EyreContext,
+    C: EyreContext,
 {
     object_drop: unsafe fn(Box<ErrorImpl<(), C>>),
     object_ref: unsafe fn(&ErrorImpl<(), C>) -> &(dyn StdError + Send + Sync + 'static),
@@ -627,12 +625,14 @@ where
     D: 'static,
 {
     if TypeId::of::<D>() == target {
-        let unerased = e as *const ErrorImpl<(), C> as *const ErrorImpl<ContextError<D, ErrReport<C>>, C>;
+        let unerased =
+            e as *const ErrorImpl<(), C> as *const ErrorImpl<ContextError<D, ErrReport<C>>, C>;
         let addr = &(*unerased)._object.msg as *const D as *mut ();
         Some(NonNull::new_unchecked(addr))
     } else {
         // Recurse down the context chain per the inner error's vtable.
-        let unerased = e as *const ErrorImpl<(), C> as *const ErrorImpl<ContextError<D, ErrReport<C>>, C>;
+        let unerased =
+            e as *const ErrorImpl<(), C> as *const ErrorImpl<ContextError<D, ErrReport<C>>, C>;
         let source = &(*unerased)._object.error;
         (source.inner.vtable.object_downcast)(&source.inner, target)
     }
@@ -717,9 +717,10 @@ where
         unsafe { &mut *(self.vtable.object_mut)(self) }
     }
 
-
     pub fn context<T: Any>(&self) -> Option<&T> {
-        self.context.context_raw(TypeId::of::<T>())?.downcast_ref::<T>()
+        self.context
+            .context_raw(TypeId::of::<T>())?
+            .downcast_ref::<T>()
     }
 
     #[cfg(backtrace)]

src/fmt.rs

@@ -1,6 +1,6 @@
 use crate::error::ErrorImpl;
-use core::fmt::{self, Write};
 use crate::EyreContext;
+use core::fmt::{self, Write};
 
 impl<C> ErrorImpl<(), C>
 where
@@ -52,6 +52,7 @@ where
 #[cfg(test)]
 mod tests {
     use super::*;
+    use crate::alloc::String;
 
     #[test]
     fn one_digit() {

src/kind.rs

@@ -44,7 +44,7 @@
 //     let error = $msg;
 //     (&error).eyre_kind().new(error)
 
-use crate::{EyreContext, ErrReport};
+use crate::{ErrReport, EyreContext};
 use core::fmt::{Debug, Display};
 
 #[cfg(feature = "std")]

src/lib.rs

@@ -195,6 +195,12 @@ mod alloc {
 
     #[cfg(feature = "std")]
     pub use std::boxed::Box;
+
+    #[cfg(not(feature = "std"))]
+    pub use alloc::string::String;
+
+    #[cfg(feature = "std")]
+    pub use std::string::String;
 }
 
 #[macro_use]
@@ -208,12 +214,11 @@ mod macros;
 mod wrapper;
 
 use crate::alloc::Box;
+use crate::backtrace::Backtrace;
 use crate::error::ErrorImpl;
+use core::any::{Any, TypeId};
 use core::fmt::Display;
 use core::mem::ManuallyDrop;
-use std::backtrace::Backtrace;
-use std::any::{Any, TypeId};
-
 
 #[cfg(not(feature = "std"))]
 use core::fmt::Debug;
@@ -222,7 +227,7 @@ use core::fmt::Debug;
 use std::error::Error as StdError;
 
 #[cfg(not(feature = "std"))]
-trait StdError: Debug + Display {
+pub trait StdError: Debug + Display {
     fn source(&self) -> Option<&(dyn StdError + 'static)> {
         None
     }
@@ -330,26 +335,32 @@ where
 }
 
 pub trait EyreContext: Sized + Send + Sync + 'static {
-    fn default(err: &(dyn std::error::Error + 'static)) -> Self;
+    fn default(err: &(dyn StdError + 'static)) -> Self;
 
     fn context_raw(&self, typeid: TypeId) -> Option<&dyn Any>;
 
-    fn display(&self, error: &(dyn std::error::Error + 'static), f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result;
+    fn display(
+        &self,
+        error: &(dyn StdError + 'static),
+        f: &mut core::fmt::Formatter<'_>,
+    ) -> core::fmt::Result;
 
-    fn debug(&self, error: &(dyn std::error::Error + 'static), f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result;
+    fn debug(
+        &self,
+        error: &(dyn StdError + 'static),
+        f: &mut core::fmt::Formatter<'_>,
+    ) -> core::fmt::Result;
 }
 
 pub struct DefaultContext {
-    pub backtrace: Option<Backtrace>,
+    backtrace: Option<Backtrace>,
 }
 
 impl EyreContext for DefaultContext {
-    fn default(error: &(dyn std::error::Error + 'static)) -> Self {
+    fn default(_error: &(dyn StdError + 'static)) -> Self {
         let backtrace = backtrace_if_absent!(error);
 
-        Self {
-            backtrace
-        }
+        Self { backtrace }
     }
 
     fn context_raw(&self, typid: TypeId) -> Option<&dyn Any> {
@@ -359,11 +370,15 @@ impl EyreContext for DefaultContext {
         }
     }
 
-    fn display(&self, error: &(dyn std::error::Error + 'static), f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+    fn display(
+        &self,
+        error: &(dyn StdError + 'static),
+        f: &mut core::fmt::Formatter<'_>,
+    ) -> core::fmt::Result {
         write!(f, "{}", error)?;
 
         if f.alternate() {
-            for cause in Chain::new(error).skip(1) {
+            for cause in crate::chain::Chain::new(error).skip(1) {
                 write!(f, ": {}", cause)?;
             }
         }
@@ -371,7 +386,11 @@ impl EyreContext for DefaultContext {
         Ok(())
     }
 
-    fn debug(&self, error: &(dyn std::error::Error + 'static), f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+    fn debug(
+        &self,
+        error: &(dyn StdError + 'static),
+        f: &mut core::fmt::Formatter<'_>,
+    ) -> core::fmt::Result {
         use core::fmt::Write as _;
 
         if f.alternate() {
@@ -383,7 +402,7 @@ impl EyreContext for DefaultContext {
         if let Some(cause) = error.source() {
             write!(f, "\n\nCaused by:")?;
             let multiple = cause.source().is_some();
-            for (n, error) in Chain::new(cause).enumerate() {
+            for (n, error) in crate::chain::Chain::new(cause).enumerate() {
                 writeln!(f)?;
                 let mut indented = fmt::Indented {
                     inner: f,
@@ -398,7 +417,11 @@ impl EyreContext for DefaultContext {
         {
             use std::backtrace::BacktraceStatus;
 
-            let backtrace = self.backtrace.as_ref().or_else(|| error.backtrace()).expect("backtrace capture failed");
+            let backtrace = self
+                .backtrace
+                .as_ref()
+                .or_else(|| error.backtrace())
+                .expect("backtrace capture failed");
             if let BacktraceStatus::Captured = backtrace.status() {
                 let mut backtrace = backtrace.to_string();
                 if backtrace.starts_with("stack backtrace:") {
@@ -650,11 +673,11 @@ where
 // Not public API. Referenced by macro-generated code.
 #[doc(hidden)]
 pub mod private {
-    use crate::{EyreContext, ErrReport};
+    use crate::{ErrReport, EyreContext};
     use core::fmt::{Debug, Display};
 
-//     #[cfg(backtrace)]
-//     use std::backtrace::Backtrace;
+    //     #[cfg(backtrace)]
+    //     use std::backtrace::Backtrace;
 
     pub use core::result::Result::Err;
 

tests/test_boxed.rs

@@ -1,4 +1,4 @@
-use eyre::{ErrReport, eyre};
+use eyre::{eyre, ErrReport};
 use std::error::Error as StdError;
 use std::io;
 use thiserror::Error;

tests/test_context.rs

@@ -1,7 +1,7 @@
 mod drop;
 
 use crate::drop::{DetectDrop, Flag};
-use eyre::{WrapErr, ErrReport, Result};
+use eyre::{ErrReport, Result, WrapErr};
 use std::fmt::{self, Display};
 use thiserror::Error;
 

tests/test_fmt.rs

@@ -1,4 +1,4 @@
-use eyre::{bail, WrapErr, Result};
+use eyre::{bail, Result, WrapErr};
 use std::io;
 
 fn f() -> Result<()> {

tests/test_macros.rs

@@ -1,7 +1,7 @@
 mod common;
 
 use self::common::*;
-use eyre::{Result, ensure};
+use eyre::{ensure, Result};
 
 #[test]
 fn test_messages() {
@@ -19,13 +19,13 @@ fn test_ensure() {
     assert!(f().is_ok());
 
     let v = 1;
-    let f = ||  -> Result<()>{
+    let f = || -> Result<()> {
         ensure!(v + v == 2, "This is correct, v: {}", v);
         Ok(())
     };
     assert!(f().is_ok());
 
-    let f = ||  -> Result<()>{
+    let f = || -> Result<()> {
         ensure!(v + v == 1, "This is not correct, v: {}", v);
         Ok(())
     };

tests/test_repr.rs

@@ -1,8 +1,8 @@
 mod drop;
 
 use self::drop::{DetectDrop, Flag};
-use eyre::ErrReport;
 use eyre::DefaultContext;
+use eyre::ErrReport;
 use std::marker::Unpin;
 use std::mem;
 
@@ -13,7 +13,10 @@ fn test_error_size() {
 
 #[test]
 fn test_null_pointer_optimization() {
-    assert_eq!(mem::size_of::<Result<(), ErrReport>>(), mem::size_of::<usize>());
+    assert_eq!(
+        mem::size_of::<Result<(), ErrReport>>(),
+        mem::size_of::<usize>()
+    );
 }
 
 #[test]
@@ -25,6 +28,8 @@ fn test_autotraits() {
 #[test]
 fn test_drop() {
     let has_dropped = Flag::new();
-    drop(ErrReport::<DefaultContext>::new(DetectDrop::new(&has_dropped)));
+    drop(ErrReport::<DefaultContext>::new(DetectDrop::new(
+        &has_dropped,
+    )));
     assert!(has_dropped.get());
 }

tests/test_source.rs

@@ -1,4 +1,4 @@
-use eyre::{ErrReport, eyre};
+use eyre::{eyre, ErrReport};
 use std::error::Error as StdError;
 use std::fmt::{self, Display};
 use std::io;