1 files changed, 52 insertions, 0 deletions
diff --git a/third_party/rust/cargo_metadata/src/errors.rs b/third_party/rust/cargo_metadata/src/errors.rs
new file mode 100644
index 0000000000..4d08200c83
--- /dev/null
+++ b/third_party/rust/cargo_metadata/src/errors.rs
@@ -0,0 +1,52 @@
+use std::{io, str::Utf8Error, string::FromUtf8Error};
+
+/// Custom result type for `cargo_metadata::Error`
+pub type Result<T> = ::std::result::Result<T, Error>;
+
+/// Error returned when executing/parsing `cargo metadata` fails.
+///
+/// # Note about Backtraces
+///
+/// This error type does not contain backtraces, but each error variant
+/// comes from _one_ specific place, so it's not really needed for the
+/// inside of this crate. If you need a backtrace down to, but not inside
+/// of, a failed call of `cargo_metadata` you can do one of multiple thinks:
+///
+/// 1. Convert it to a `failure::Error` (possible using the `?` operator),
+///    which is similar to a `Box<::std::error::Error + 'static + Send  + Sync>`.
+/// 2. Have appropriate variants in your own error type. E.g. you could wrap
+///    a `failure::Context<Error>` or add a `failure::Backtrace` field (which
+///    is empty if `RUST_BACKTRACE` is not set, so it's simple to use).
+/// 3. You still can place a failure based error into a `error_chain` if you
+///    really want to. (Either through foreign_links or by making it a field
+///    value of a `ErrorKind` variant).
+///
+#[derive(Debug, thiserror::Error)]
+pub enum Error {
+    /// Error during execution of `cargo metadata`
+    #[error("`cargo metadata` exited with an error: {stderr}")]
+    CargoMetadata {
+        /// stderr returned by the `cargo metadata` command
+        stderr: String,
+    },
+
+    /// IO Error during execution of `cargo metadata`
+    #[error("failed to start `cargo metadata`: {0}")]
+    Io(#[from] io::Error),
+
+    /// Output of `cargo metadata` was not valid utf8
+    #[error("cannot convert the stdout of `cargo metadata`: {0}")]
+    Utf8(#[from] Utf8Error),
+
+    /// Error output of `cargo metadata` was not valid utf8
+    #[error("cannot convert the stderr of `cargo metadata`: {0}")]
+    ErrUtf8(#[from] FromUtf8Error),
+
+    /// Deserialization error (structure of json did not match expected structure)
+    #[error("failed to interpret `cargo metadata`'s json: {0}")]
+    Json(#[from] ::serde_json::Error),
+
+    /// The output did not contain any json
+    #[error("could not find any json in the output of `cargo metadata`")]
+    NoJson,
+}