Import anyhow-1.0.28

Change-Id: I004738cd6c92decd379de4e4b85ec925de956d12

1 files changed, 62 insertions, 0 deletions

diff --git a/build.rs b/build.rs
new file mode 100644
index 0000000..056164d
--- /dev/null
+++ b/build.rs
@@ -0,0 +1,62 @@
+use std::env;
+use std::fs;
+use std::path::Path;
+use std::process::{Command, ExitStatus};
+
+// This code exercises the surface area that we expect of the std Backtrace
+// type. If the current toolchain is able to compile it, we go ahead and use
+// backtrace in anyhow.
+const PROBE: &str = r#"
+    #![feature(backtrace)]
+    #![allow(dead_code)]
+
+    use std::backtrace::{Backtrace, BacktraceStatus};
+    use std::error::Error;
+    use std::fmt::{self, Display};
+
+    #[derive(Debug)]
+    struct E;
+
+    impl Display for E {
+        fn fmt(&self, _formatter: &mut fmt::Formatter) -> fmt::Result {
+            unimplemented!()
+        }
+    }
+
+    impl Error for E {
+        fn backtrace(&self) -> Option<&Backtrace> {
+            let backtrace = Backtrace::capture();
+            match backtrace.status() {
+                BacktraceStatus::Captured | BacktraceStatus::Disabled | _ => {}
+            }
+            unimplemented!()
+        }
+    }
+"#;
+
+fn main() {
+    if !cfg!(feature = "std") {
+        return;
+    }
+    match compile_probe() {
+        Some(status) if status.success() => println!("cargo:rustc-cfg=backtrace"),
+        _ => {}
+    }
+}
+
+fn compile_probe() -> Option<ExitStatus> {
+    let rustc = env::var_os("RUSTC")?;
+    let out_dir = env::var_os("OUT_DIR")?;
+    let probefile = Path::new(&out_dir).join("probe.rs");
+    fs::write(&probefile, PROBE).ok()?;
+    Command::new(rustc)
+        .arg("--edition=2018")
+        .arg("--crate-name=anyhow_build")
+        .arg("--crate-type=lib")
+        .arg("--emit=metadata")
+        .arg("--out-dir")
+        .arg(out_dir)
+        .arg(probefile)
+        .status()
+        .ok()
+}