Improve error message for failed replacements

src/error.rs

@@ -1,3 +1,8 @@
+use std::{
+    fmt::{self, Write},
+    path::PathBuf,
+};
+
 #[derive(thiserror::Error)]
 pub enum Error {
     #[error("invalid regex {0}")]
@@ -7,7 +12,27 @@ pub enum Error {
     #[error("failed to move file: {0}")]
     TempfilePersist(#[from] tempfile::PersistError),
     #[error("file doesn't have parent path: {0}")]
-    InvalidPath(std::path::PathBuf),
+    InvalidPath(PathBuf),
+    #[error("failed processing files:\n{0}")]
+    FailedProcessing(FailedJobs),
+}
+
+pub struct FailedJobs(Vec<(PathBuf, Error)>);
+
+impl From<Vec<(PathBuf, Error)>> for FailedJobs {
+    fn from(vec: Vec<(PathBuf, Error)>) -> Self {
+        Self(vec)
+    }
+}
+
+impl fmt::Display for FailedJobs {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.write_str("\tFailedJobs(\n")?;
+        for (path, err) in &self.0 {
+            f.write_str(&format!("\t{:?}: {}\n", path, err))?;
+        }
+        f.write_char(')')
+    }
 }
 
 // pretty-print the error

src/input.rs

@@ -1,4 +1,4 @@
-use crate::{Replacer, Result};
+use crate::{Error, Replacer, Result};
 use std::{fs::File, io::prelude::*, path::PathBuf};
 
 #[derive(Debug)]
@@ -57,14 +57,24 @@ impl App {
             (Source::Files(paths), false) => {
                 use rayon::prelude::*;
 
-                #[allow(unused_must_use)]
-                paths.par_iter().for_each(|p| {
-                    self.replacer.replace_file(p).map_err(|e| {
-                        eprintln!("Error processing {}: {}", p.display(), e)
-                    });
-                });
+                let failed_jobs: Vec<_> = paths
+                    .par_iter()
+                    .filter_map(|p| {
+                        if let Err(e) = self.replacer.replace_file(p) {
+                            Some((p.to_owned(), e))
+                        } else {
+                            None
+                        }
+                    })
+                    .collect();
 
-                Ok(())
+                if failed_jobs.is_empty() {
+                    Ok(())
+                } else {
+                    let failed_jobs =
+                        crate::error::FailedJobs::from(failed_jobs);
+                    Err(Error::FailedProcessing(failed_jobs))
+                }
             }
             (Source::Files(paths), true) => {
                 let stdout = std::io::stdout();