Gracefully handle ErrorKind::BrokenPipe (public-api ... | head -n 1)

So that we don't get an error when doing something like this:

    % RUSTDOCFLAGS='-Z unstable-options --output-format json' cargo +nightly doc  --manifest-path tests/crates/comprehensive_api/Cargo.toml --lib --no-deps
    % ./target/debug/public-api tests/crates/comprehensive_api/target/doc/comprehensive_api.json | head -n 1
    pub async fn comprehensive_api::functions::async_fn() -> impl Future<Output = ()>
    Error: Os { code: 32, kind: BrokenPipe, message: "Broken pipe" }

Author: Enselic

src/main.rs

@@ -1,10 +1,18 @@
-use std::io::{stdout, Write};
+use std::io::{stdout, ErrorKind, Write};
 use std::path::{Path, PathBuf};
 
 use public_api::diff::PublicItemsDiff;
 use public_api::{public_api_from_rustdoc_json_str, Options, MINIMUM_RUSTDOC_JSON_VERSION};
 
-type Result<T> = std::result::Result<T, Box<dyn std::error::Error>>;
+#[derive(thiserror::Error, Debug)]
+enum Error {
+    #[error(transparent)]
+    PublicApiError(#[from] public_api::Error),
+    #[error(transparent)]
+    StdIoError(#[from] std::io::Error),
+}
+
+type Result<T> = std::result::Result<T, Error>;
 
 #[derive(Default)]
 struct Args {
@@ -13,7 +21,7 @@ struct Args {
     files: Vec<PathBuf>,
 }
 
-fn main() -> Result<()> {
+fn main_() -> Result<()> {
     let args = args();
 
     let mut options = Options::default();
@@ -155,3 +163,11 @@ fn args() -> Args {
 
     args
 }
+
+/// Wrapper to handle <https://github.com/rust-lang/rust/issues/46016>
+fn main() -> Result<()> {
+    match main_() {
+        Err(Error::StdIoError(e)) if e.kind() == ErrorKind::BrokenPipe => std::process::exit(141),
+        result => result,
+    }
+}

tests/bin_tests.rs

@@ -1,3 +1,5 @@
+use std::{io::BufRead, str::from_utf8};
+
 use assert_cmd::Command;
 use public_api::MINIMUM_RUSTDOC_JSON_VERSION;
 
@@ -120,6 +122,30 @@ Added:
     );
 }
 
+/// Uses a bash one-liner to test that public-api gracefully handles
+/// `std::io::ErrorKind::BrokenPipe`
+#[test]
+#[serial]
+fn broken_pipe() {
+    // Use the JSON for a somewhat large API so the pipe has time to become closed
+    // before all output has been written to stdout
+    let large_api = rustdoc_json_path_for_crate("./tests/crates/comprehensive_api");
+
+    // Now setup the actual one-liner
+    let mut cmd = std::process::Command::new("bash");
+    cmd.args([
+        "-c",
+        &format!(
+            "./target/debug/public-api {} | head -n 1",
+            large_api.to_string_lossy(),
+        ),
+    ]);
+
+    // Run it and assert on that there was no error printed
+    assert_eq!(cmd.output().unwrap().stdout.lines().count(), 1);
+    assert_eq!(from_utf8(&cmd.output().unwrap().stderr), Ok(""));
+}
+
 #[test]
 fn short_help() {
     let mut cmd = Command::cargo_bin("public-api").unwrap();