Merge pull request #331 from dtolnay/backtrace

Separate cfgs for Backtrace vs Error::provide
dtolnay · Dec 26, 2023 · cf66194 · cf66194
2 parents 5121cd2 + 53d6076
commit cf66194
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Showing 6 changed files with 59 additions and 25 deletions.
diff --git a/build.rs b/build.rs
@@ -50,7 +50,10 @@ fn main() {
         println!("cargo:rerun-if-env-changed=RUSTC_BOOTSTRAP");
 
         match compile_probe() {
-            Some(status) if status.success() => println!("cargo:rustc-cfg=backtrace"),
+            Some(status) if status.success() => {
+                println!("cargo:rustc-cfg=backtrace");
+                println!("cargo:rustc-cfg=error_generic_member_access");
+            }
             _ => {}
         }
     }

diff --git a/src/backtrace.rs b/src/backtrace.rs
@@ -35,7 +35,7 @@ macro_rules! backtrace {
     };
 }
 
-#[cfg(backtrace)]
+#[cfg(error_generic_member_access)]
 macro_rules! backtrace_if_absent {
     ($err:expr) => {
         match std::error::request_ref::<std::backtrace::Backtrace>($err as &dyn std::error::Error) {
@@ -45,7 +45,11 @@ macro_rules! backtrace_if_absent {
     };
 }
 
-#[cfg(all(feature = "std", not(backtrace), feature = "backtrace"))]
+#[cfg(all(
+    feature = "std",
+    not(error_generic_member_access),
+    any(backtrace, feature = "backtrace")
+))]
 macro_rules! backtrace_if_absent {
     ($err:expr) => {
         backtrace!()

diff --git a/src/context.rs b/src/context.rs
@@ -3,7 +3,7 @@ use crate::{Context, Error, StdError};
 use core::convert::Infallible;
 use core::fmt::{self, Debug, Display, Write};
 
-#[cfg(backtrace)]
+#[cfg(error_generic_member_access)]
 use std::error::Request;
 
 mod ext {
@@ -143,7 +143,7 @@ where
         Some(&self.error)
     }
 
-    #[cfg(backtrace)]
+    #[cfg(error_generic_member_access)]
     fn provide<'a>(&'a self, request: &mut Request<'a>) {
         StdError::provide(&self.error, request);
     }
@@ -157,7 +157,7 @@ where
         Some(unsafe { crate::ErrorImpl::error(self.error.inner.by_ref()) })
     }
 
-    #[cfg(backtrace)]
+    #[cfg(error_generic_member_access)]
     fn provide<'a>(&'a self, request: &mut Request<'a>) {
         Error::provide(&self.error, request);
     }

diff --git a/src/error.rs b/src/error.rs
@@ -11,7 +11,7 @@ use core::mem::ManuallyDrop;
 #[cfg(not(anyhow_no_ptr_addr_of))]
 use core::ptr;
 use core::ptr::NonNull;
-#[cfg(backtrace)]
+#[cfg(error_generic_member_access)]
 use std::error::{self, Request};
 
 #[cfg(feature = "std")]
@@ -99,7 +99,10 @@ impl Error {
             #[cfg(anyhow_no_ptr_addr_of)]
             object_downcast_mut: object_downcast_mut::<E>,
             object_drop_rest: object_drop_front::<E>,
-            #[cfg(all(not(backtrace), feature = "backtrace"))]
+            #[cfg(all(
+                not(error_generic_member_access),
+                any(backtrace, feature = "backtrace")
+            ))]
             object_backtrace: no_backtrace,
         };
 
@@ -124,7 +127,10 @@ impl Error {
             #[cfg(anyhow_no_ptr_addr_of)]
             object_downcast_mut: object_downcast_mut::<M>,
             object_drop_rest: object_drop_front::<M>,
-            #[cfg(all(not(backtrace), feature = "backtrace"))]
+            #[cfg(all(
+                not(error_generic_member_access),
+                any(backtrace, feature = "backtrace")
+            ))]
             object_backtrace: no_backtrace,
         };
 
@@ -150,7 +156,10 @@ impl Error {
             #[cfg(anyhow_no_ptr_addr_of)]
             object_downcast_mut: object_downcast_mut::<M>,
             object_drop_rest: object_drop_front::<M>,
-            #[cfg(all(not(backtrace), feature = "backtrace"))]
+            #[cfg(all(
+                not(error_generic_member_access),
+                any(backtrace, feature = "backtrace")
+            ))]
             object_backtrace: no_backtrace,
         };
 
@@ -178,7 +187,10 @@ impl Error {
             #[cfg(anyhow_no_ptr_addr_of)]
             object_downcast_mut: context_downcast_mut::<C, E>,
             object_drop_rest: context_drop_rest::<C, E>,
-            #[cfg(all(not(backtrace), feature = "backtrace"))]
+            #[cfg(all(
+                not(error_generic_member_access),
+                any(backtrace, feature = "backtrace")
+            ))]
             object_backtrace: no_backtrace,
         };
 
@@ -204,7 +216,10 @@ impl Error {
             #[cfg(anyhow_no_ptr_addr_of)]
             object_downcast_mut: object_downcast_mut::<Box<dyn StdError + Send + Sync>>,
             object_drop_rest: object_drop_front::<Box<dyn StdError + Send + Sync>>,
-            #[cfg(all(not(backtrace), feature = "backtrace"))]
+            #[cfg(all(
+                not(error_generic_member_access),
+                any(backtrace, feature = "backtrace")
+            ))]
             object_backtrace: no_backtrace,
         };
 
@@ -317,7 +332,10 @@ impl Error {
             #[cfg(anyhow_no_ptr_addr_of)]
             object_downcast_mut: context_chain_downcast_mut::<C>,
             object_drop_rest: context_chain_drop_rest::<C>,
-            #[cfg(all(not(backtrace), feature = "backtrace"))]
+            #[cfg(all(
+                not(error_generic_member_access),
+                any(backtrace, feature = "backtrace")
+            ))]
             object_backtrace: context_backtrace::<C>,
         };
 
@@ -523,7 +541,7 @@ impl Error {
         }
     }
 
-    #[cfg(backtrace)]
+    #[cfg(error_generic_member_access)]
     pub(crate) fn provide<'a>(&'a self, request: &mut Request<'a>) {
         unsafe { ErrorImpl::provide(self.inner.by_ref(), request) }
     }
@@ -533,7 +551,7 @@ impl Error {
     // deref'ing to dyn Error where the provide implementation would include
     // only the original error's Backtrace from before it got wrapped into an
     // anyhow::Error.
-    #[cfg(backtrace)]
+    #[cfg(error_generic_member_access)]
     #[doc(hidden)]
     pub fn thiserror_provide<'a>(&'a self, request: &mut Request<'a>) {
         Self::provide(self, request);
@@ -602,7 +620,10 @@ struct ErrorVTable {
     #[cfg(anyhow_no_ptr_addr_of)]
     object_downcast_mut: unsafe fn(Mut<ErrorImpl>, TypeId) -> Option<Mut<()>>,
     object_drop_rest: unsafe fn(Own<ErrorImpl>, TypeId),
-    #[cfg(all(not(backtrace), feature = "backtrace"))]
+    #[cfg(all(
+        not(error_generic_member_access),
+        any(backtrace, feature = "backtrace")
+    ))]
     object_backtrace: unsafe fn(Ref<ErrorImpl>) -> Option<&Backtrace>,
 }
 
@@ -707,7 +728,10 @@ where
     }
 }
 
-#[cfg(all(not(backtrace), feature = "backtrace"))]
+#[cfg(all(
+    not(error_generic_member_access),
+    any(backtrace, feature = "backtrace")
+))]
 fn no_backtrace(e: Ref<ErrorImpl>) -> Option<&Backtrace> {
     let _ = e;
     None
@@ -828,7 +852,10 @@ where
 }
 
 // Safety: requires layout of *e to match ErrorImpl<ContextError<C, Error>>.
-#[cfg(all(not(backtrace), feature = "backtrace"))]
+#[cfg(all(
+    not(error_generic_member_access),
+    any(backtrace, feature = "backtrace")
+))]
 #[allow(clippy::unnecessary_wraps)]
 unsafe fn context_backtrace<C>(e: Ref<ErrorImpl>) -> Option<&Backtrace>
 where
@@ -908,15 +935,15 @@ impl ErrorImpl {
             .backtrace
             .as_ref()
             .or_else(|| {
-                #[cfg(backtrace)]
+                #[cfg(error_generic_member_access)]
                 return error::request_ref::<Backtrace>(unsafe { Self::error(this) });
-                #[cfg(not(backtrace))]
+                #[cfg(not(error_generic_member_access))]
                 return unsafe { (vtable(this.ptr).object_backtrace)(this) };
             })
             .expect("backtrace capture failed")
     }
 
-    #[cfg(backtrace)]
+    #[cfg(error_generic_member_access)]
     unsafe fn provide<'a>(this: Ref<'a, Self>, request: &mut Request<'a>) {
         if let Some(backtrace) = unsafe { &this.deref().backtrace } {
             request.provide_ref(backtrace);
@@ -938,7 +965,7 @@ where
         unsafe { ErrorImpl::error(self.erase()).source() }
     }
 
-    #[cfg(backtrace)]
+    #[cfg(error_generic_member_access)]
     fn provide<'a>(&'a self, request: &mut Request<'a>) {
         unsafe { ErrorImpl::provide(self.erase(), request) }
     }

diff --git a/src/lib.rs b/src/lib.rs
@@ -211,7 +211,7 @@
 //! non-Anyhow error type inside a function that returns Anyhow's error type.
 
 #![doc(html_root_url = "https://docs.rs/anyhow/1.0.76")]
-#![cfg_attr(backtrace, feature(error_generic_member_access))]
+#![cfg_attr(error_generic_member_access, feature(error_generic_member_access))]
 #![cfg_attr(doc_cfg, feature(doc_cfg))]
 #![cfg_attr(not(feature = "std"), no_std)]
 #![deny(dead_code, unused_imports, unused_mut)]

diff --git a/src/wrapper.rs b/src/wrapper.rs
@@ -1,7 +1,7 @@
 use crate::StdError;
 use core::fmt::{self, Debug, Display};
 
-#[cfg(backtrace)]
+#[cfg(error_generic_member_access)]
 use std::error::Request;
 
 #[repr(transparent)]
@@ -74,7 +74,7 @@ impl StdError for BoxedError {
         self.0.source()
     }
 
-    #[cfg(backtrace)]
+    #[cfg(error_generic_member_access)]
     fn provide<'a>(&'a self, request: &mut Request<'a>) {
         self.0.provide(request);
     }