Use std::backtrace::Backtrace as the default backtrace provider

This also bumps our default Rust version to 1.65.

Closes #357

.cirrus.yml

@@ -16,8 +16,6 @@ stable_test_task:
   primary_test_script:
     - rustc --version
     - cargo test --all
-  backtrace_shim_test_script:
-    - cargo test --manifest-path compatibility-tests/backtrace-shim/Cargo.toml
   backtraces_impl_backtrace_crate_test_script:
     - cargo test --manifest-path compatibility-tests/backtraces-impl-backtrace-crate/Cargo.toml
   context_selectors_have_documentation_test_script:
@@ -63,8 +61,6 @@ doc_test_task:
     - rustc +nightly --version
   docs_script:
     - cargo +nightly doc
-  backtraces_docs_script:
-    - cargo +nightly doc --features=backtraces
   backtraces_impl_backtrace_crate_docs_script:
     - cargo +nightly doc --features=backtraces-impl-backtrace-crate
   futures_docs_script:
@@ -82,8 +78,6 @@ doc_tests_task:
     fingerprint_script: cat Cargo.toml
   version_information_script:
     - rustc +nightly --version
-  backtraces_doctests_script:
-    - cargo +nightly test --doc --features=backtraces
   backtraces_impl_backtrace_crate_doctests_script:
     - cargo +nightly test --doc --features=backtraces-impl-backtrace-crate
   futures_doctests_script:
@@ -171,35 +165,35 @@ nightly_test_task:
     - cargo test
   before_cache_script: rm -rf $CARGO_HOME/registry/index
 
-std_backtraces_test_task:
-  name: "Rust Beta (backtraces)"
+# Our Minimal Supported Rust Version (MSRV)
+v1_56_test_task:
+  name: "Rust 1.56"
   container:
-    image: rust:latest
+    image: rust:1.56
     cpu: 1
     memory: 2Gi
   cargo_cache:
     folder: $CARGO_HOME/registry
     fingerprint_script: cat Cargo.toml
-  setup_script:
-    - rustup toolchain install beta
-  backtraces_impl_std_test_script:
-    - cd compatibility-tests/backtraces-impl-std && RUST_BACKTRACE=1 cargo test
-  backtraces_impl_std_docs_script:
-    - cargo +beta doc --features=backtraces-impl-std
+  primary_test_script:
+    - rustup self update
+    - cd compatibility-tests/v1_56/
+    - rustc --version
+    - cargo test
   before_cache_script: rm -rf $CARGO_HOME/registry/index
 
-v1_56_test_task:
-  name: "Rust 1.56"
+v1_61_test_task:
+  name: "Rust 1.61"
   container:
-    image: rust:1.56
+    image: rust:1.61
     cpu: 1
     memory: 2Gi
   cargo_cache:
     folder: $CARGO_HOME/registry
     fingerprint_script: cat Cargo.toml
   primary_test_script:
     - rustup self update
-    - cd compatibility-tests/v1_56/
+    - cd compatibility-tests/v1_61/
     - rustc --version
     - cargo test
   before_cache_script: rm -rf $CARGO_HOME/registry/index

Cargo.toml

@@ -22,11 +22,14 @@ exclude = [
 ]
 
 [package.metadata.docs.rs]
-# The backtraces-impl-* features are incompatible with each other
-features = [ "std", "backtraces", "futures", "guide" ]
+# We don't use `all-features` for a few reasons:
+# - `backtraces-impl-backtrace-crate` replaces the default stdlib implementation
+# - `unstable-*` features might break with little warning
+# - `internal-dev-dependencies` is internal
+features = ["futures", "guide"]
 
 [features]
-default = ["std", "rust_1_61"]
+default = ["std", "rust_1_65"]
 
 # Implement the `std::error::Error` trait.
 std = []
@@ -37,14 +40,11 @@ unstable-core-error = []
 # Add support for `Termination` for `Report`
 rust_1_61 = ["snafu-derive/rust_1_61"]
 
-# Makes the backtrace type live
-backtraces = ["std", "backtrace"]
+# `Backtrace` was stabilized
+rust_1_65 = ["rust_1_61"]
 
 # The backtrace type becomes `backtrace::Backtrace`
-backtraces-impl-backtrace-crate = ["backtraces"]
-
-# The backtrace type becomes `std::backtrace::Backtrace`
-backtraces-impl-std = []
+backtraces-impl-backtrace-crate = ["backtrace"]
 
 # The std::error::Error provider API will be implemented.
 unstable-provider-api = ["snafu-derive/unstable-provider-api"]

compatibility-tests/report-provider-api/Cargo.toml

@@ -6,4 +6,4 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-snafu = { path = "../..", features = ["backtraces-impl-std", "unstable-provider-api"] }
+snafu = { path = "../..", features = ["unstable-provider-api"] }

compatibility-tests/v1_56/Cargo.toml

@@ -5,4 +5,4 @@ authors = ["Jake Goulding <[email protected]>"]
 edition = "2018"
 
 [dependencies]
-snafu = { path = "../..", default-features = false, features = ["backtraces"] }
+snafu = { path = "../..", default-features = false, features = ["std"] }

compatibility-tests/backtrace-shim/Cargo.toml → compatibility-tests/v1_61/Cargo.toml

@@ -1,8 +1,8 @@
 [package]
-name = "backtrace-shim"
+name = "v1_61"
 version = "0.1.0"
 authors = ["Jake Goulding <[email protected]>"]
 edition = "2018"
 
 [dependencies]
-snafu = { path = "../..", features = ["backtraces"] }
+snafu = { path = "../..", default-features = false, features = ["std", "rust_1_61"] }

compatibility-tests/v1_61/rust-toolchain

@@ -0,0 +1 @@
+1.61

compatibility-tests/v1_61/src/lib.rs

@@ -0,0 +1,58 @@
+#![cfg(test)]
+
+use snafu::{prelude::*, Backtrace, ErrorCompat};
+
+type AnotherError = Box<dyn std::error::Error>;
+
+#[derive(Debug, Snafu)]
+enum Error {
+    #[snafu(display("Invalid user {}:\n{}", user_id, backtrace))]
+    InvalidUser { user_id: i32, backtrace: Backtrace },
+    WithSource {
+        source: AnotherError,
+        backtrace: Backtrace,
+    },
+    WithSourceAndOtherInfo {
+        user_id: i32,
+        source: AnotherError,
+        backtrace: Backtrace,
+    },
+}
+
+type Result<T, E = Error> = std::result::Result<T, E>;
+
+fn example(user_id: i32) -> Result<()> {
+    ensure!(user_id >= 42, InvalidUserSnafu { user_id });
+    Ok(())
+}
+
+#[test]
+fn display_can_access_backtrace() {
+    let e = example(0).unwrap_err();
+    let text = e.to_string();
+    assert!(
+        text.contains("disabled backtrace"),
+        "{:?} does not contain expected text",
+        text
+    );
+}
+
+fn trigger() -> Result<(), AnotherError> {
+    Err("boom".into())
+}
+
+#[test]
+fn errors_with_sources_can_have_backtraces() {
+    let e = trigger().context(WithSourceSnafu).unwrap_err();
+    let backtrace = ErrorCompat::backtrace(&e).unwrap();
+    assert!(backtrace.to_string().contains("disabled backtrace"));
+}
+
+#[test]
+fn errors_with_sources_and_other_info_can_have_backtraces() {
+    let e = trigger()
+        .context(WithSourceAndOtherInfoSnafu { user_id: 42 })
+        .unwrap_err();
+    let backtrace = ErrorCompat::backtrace(&e).unwrap();
+    assert!(backtrace.to_string().contains("disabled backtrace"));
+}

netlify.toml

@@ -1,7 +1,7 @@
 [build]
 command = """
 rustup install nightly --profile minimal && \
-cargo +nightly doc --no-deps --features=std,backtraces,futures,guide
+cargo +nightly doc --no-deps --features=futures,guide
 """
 publish = "target/doc"
 

src/backtrace_impl_backtrace_crate.rs

@@ -0,0 +1,13 @@
+pub use backtrace::Backtrace;
+
+impl crate::GenerateImplicitData for Backtrace {
+    fn generate() -> Self {
+        Backtrace::new()
+    }
+}
+
+impl crate::AsBacktrace for Backtrace {
+    fn as_backtrace(&self) -> Option<&Backtrace> {
+        Some(self)
+    }
+}