Switch from error-chain to anyhow.

Author: ehuss

Cargo.lock

@@ -16,10 +16,10 @@ repository = "https://github.com/rust-lang/mdBook"
 description = "Creates a book from markdown files"
 
 [dependencies]
+anyhow = "1.0.28"
 chrono = "0.4"
 clap = "2.24"
 env_logger = "0.7.1"
-error-chain = "0.12"
 handlebars = "3.0"
 lazy_static = "1.0"
 log = "0.4"

Cargo.toml

@@ -87,7 +87,7 @@ mod nop_lib {
             // particular config value
             if let Some(nop_cfg) = ctx.config.get_preprocessor(self.name()) {
                 if nop_cfg.contains_key("blow-up") {
-                    return Err("Boom!!1!".into());
+                    anyhow::bail!("Boom!!1!");
                 }
             }
 

examples/nop-preprocessor.rs

@@ -15,13 +15,13 @@ pub fn load_book<P: AsRef<Path>>(src_dir: P, cfg: &BuildConfig) -> Result<Book>
 
     let mut summary_content = String::new();
     File::open(summary_md)
-        .chain_err(|| "Couldn't open SUMMARY.md")?
+        .with_context(|| "Couldn't open SUMMARY.md")?
         .read_to_string(&mut summary_content)?;
 
-    let summary = parse_summary(&summary_content).chain_err(|| "Summary parsing failed")?;
+    let summary = parse_summary(&summary_content).with_context(|| "Summary parsing failed")?;
 
     if cfg.create_missing {
-        create_missing(&src_dir, &summary).chain_err(|| "Unable to create missing chapters")?;
+        create_missing(&src_dir, &summary).with_context(|| "Unable to create missing chapters")?;
     }
 
     load_book_from_disk(&summary, src_dir)
@@ -257,11 +257,12 @@ fn load_chapter<P: AsRef<Path>>(
         };
 
         let mut f = File::open(&location)
-            .chain_err(|| format!("Chapter file not found, {}", link_location.display()))?;
+            .with_context(|| format!("Chapter file not found, {}", link_location.display()))?;
 
         let mut content = String::new();
-        f.read_to_string(&mut content)
-            .chain_err(|| format!("Unable to read \"{}\" ({})", link.name, location.display()))?;
+        f.read_to_string(&mut content).with_context(|| {
+            format!("Unable to read \"{}\" ({})", link.name, location.display())
+        })?;
 
         let stripped = location
             .strip_prefix(&src_dir)

src/book/book.rs

@@ -64,19 +64,19 @@ impl BookBuilder {
         info!("Creating a new book with stub content");
 
         self.create_directory_structure()
-            .chain_err(|| "Unable to create directory structure")?;
+            .with_context(|| "Unable to create directory structure")?;
 
         self.create_stub_files()
-            .chain_err(|| "Unable to create stub files")?;
+            .with_context(|| "Unable to create stub files")?;
 
         if self.create_gitignore {
             self.build_gitignore()
-                .chain_err(|| "Unable to create .gitignore")?;
+                .with_context(|| "Unable to create .gitignore")?;
         }
 
         if self.copy_theme {
             self.copy_across_theme()
-                .chain_err(|| "Unable to copy across the theme")?;
+                .with_context(|| "Unable to copy across the theme")?;
         }
 
         self.write_book_toml()?;
@@ -97,12 +97,12 @@ impl BookBuilder {
     fn write_book_toml(&self) -> Result<()> {
         debug!("Writing book.toml");
         let book_toml = self.root.join("book.toml");
-        let cfg = toml::to_vec(&self.config).chain_err(|| "Unable to serialize the config")?;
+        let cfg = toml::to_vec(&self.config).with_context(|| "Unable to serialize the config")?;
 
         File::create(book_toml)
-            .chain_err(|| "Couldn't create book.toml")?
+            .with_context(|| "Couldn't create book.toml")?
             .write_all(&cfg)
-            .chain_err(|| "Unable to write config to book.toml")?;
+            .with_context(|| "Unable to write config to book.toml")?;
         Ok(())
     }
 
@@ -174,13 +174,14 @@ impl BookBuilder {
         let summary = src_dir.join("SUMMARY.md");
         if !summary.exists() {
             trace!("No summary found creating stub summary and chapter_1.md.");
-            let mut f = File::create(&summary).chain_err(|| "Unable to create SUMMARY.md")?;
+            let mut f = File::create(&summary).with_context(|| "Unable to create SUMMARY.md")?;
             writeln!(f, "# Summary")?;
             writeln!(f)?;
             writeln!(f, "- [Chapter 1](./chapter_1.md)")?;
 
             let chapter_1 = src_dir.join("chapter_1.md");
-            let mut f = File::create(&chapter_1).chain_err(|| "Unable to create chapter_1.md")?;
+            let mut f =
+                File::create(&chapter_1).with_context(|| "Unable to create chapter_1.md")?;
             writeln!(f, "# Chapter 1")?;
         } else {
             trace!("Existing summary found, no need to create stub files.");

src/book/init.rs

@@ -215,7 +215,7 @@ impl MDBook {
 
         renderer
             .render(&render_context)
-            .chain_err(|| "Rendering failed")
+            .with_context(|| "Rendering failed")
     }
 
     /// You can change the default renderer to another one by using this method.
@@ -282,10 +282,12 @@ impl MDBook {
                 let output = cmd.output()?;
 
                 if !output.status.success() {
-                    bail!(ErrorKind::Subprocess(
-                        "Rustdoc returned an error".to_string(),
-                        output
-                    ));
+                    bail!(
+                        "rustdoc returned an error:\n\
+                        \n--- stdout\n{}\n--- stderr\n{}",
+                        String::from_utf8_lossy(&output.stdout),
+                        String::from_utf8_lossy(&output.stderr)
+                    );
                 }
             }
         }

src/book/mod.rs

@@ -236,13 +236,13 @@ impl<'a> SummaryParser<'a> {
 
         let prefix_chapters = self
             .parse_affix(true)
-            .chain_err(|| "There was an error parsing the prefix chapters")?;
+            .with_context(|| "There was an error parsing the prefix chapters")?;
         let numbered_chapters = self
             .parse_parts()
-            .chain_err(|| "There was an error parsing the numbered chapters")?;
+            .with_context(|| "There was an error parsing the numbered chapters")?;
         let suffix_chapters = self
             .parse_affix(false)
-            .chain_err(|| "There was an error parsing the suffix chapters")?;
+            .with_context(|| "There was an error parsing the suffix chapters")?;
 
         Ok(Summary {
             title,
@@ -320,7 +320,7 @@ impl<'a> SummaryParser<'a> {
             // Parse the rest of the part.
             let numbered_chapters = self
                 .parse_numbered(&mut root_items, &mut root_number)
-                .chain_err(|| "There was an error parsing the numbered chapters")?;
+                .with_context(|| "There was an error parsing the numbered chapters")?;
 
             if let Some(title) = title {
                 parts.push(SummaryItem::PartTitle(title));
@@ -514,8 +514,12 @@ impl<'a> SummaryParser<'a> {
 
     fn parse_error<D: Display>(&self, msg: D) -> Error {
         let (line, col) = self.current_location();
-
-        ErrorKind::ParseError(line, col, msg.to_string()).into()
+        anyhow::anyhow!(
+            "failed to parse SUMMARY.md line {}, column {}: {}",
+            line,
+            col,
+            msg
+        )
     }
 
     /// Try to parse the title line.
@@ -553,10 +557,9 @@ fn get_last_link(links: &mut [SummaryItem]) -> Result<(usize, &mut Link)> {
         .filter_map(|(i, item)| item.maybe_link_mut().map(|l| (i, l)))
         .rev()
         .next()
-        .ok_or_else(|| {
-            "Unable to get last link because the list of SummaryItems doesn't contain any Links"
-                .into()
-        })
+        .ok_or_else(||
+            anyhow::anyhow!("Unable to get last link because the list of SummaryItems doesn't contain any Links")
+            )
 }
 
 /// Removes the styling from a list of Markdown events and returns just the

src/book/summary.rs

@@ -1,6 +1,6 @@
 use crate::get_book_dir;
+use anyhow::Context;
 use clap::{App, ArgMatches, SubCommand};
-use mdbook::errors::*;
 use mdbook::MDBook;
 use std::fs;
 
@@ -31,7 +31,8 @@ pub fn execute(args: &ArgMatches) -> mdbook::errors::Result<()> {
     };
 
     if dir_to_remove.exists() {
-        fs::remove_dir_all(&dir_to_remove).chain_err(|| "Unable to remove the build directory")?;
+        fs::remove_dir_all(&dir_to_remove)
+            .with_context(|| "Unable to remove the build directory")?;
     }
 
     Ok(())

src/cmd/clean.rs

@@ -74,7 +74,7 @@ pub fn execute(args: &ArgMatches) -> Result<()> {
     let sockaddr: SocketAddr = address
         .to_socket_addrs()?
         .next()
-        .ok_or_else(|| format!("no address found for {}", address))?;
+        .ok_or_else(|| anyhow::anyhow!("no address found for {}", address))?;
     let build_dir = book.build_dir_for("html");
 
     // A channel used to broadcast to any websockets to reload when a file changes.

src/cmd/serve.rs

@@ -79,7 +79,7 @@ impl FromStr for Config {
 
     /// Load a `Config` from some string.
     fn from_str(src: &str) -> Result<Self> {
-        toml::from_str(src).chain_err(|| Error::from("Invalid configuration file"))
+        toml::from_str(src).with_context(|| "Invalid configuration file")
     }
 }
 
@@ -88,9 +88,9 @@ impl Config {
     pub fn from_disk<P: AsRef<Path>>(config_file: P) -> Result<Config> {
         let mut buffer = String::new();
         File::open(config_file)
-            .chain_err(|| "Unable to open the configuration file")?
+            .with_context(|| "Unable to open the configuration file")?
             .read_to_string(&mut buffer)
-            .chain_err(|| "Couldn't read the file")?;
+            .with_context(|| "Couldn't read the file")?;
 
         Config::from_str(&buffer)
     }
@@ -176,11 +176,14 @@ impl Config {
     /// HTML renderer is refactored to be less coupled to `mdbook` internals.
     #[doc(hidden)]
     pub fn html_config(&self) -> Option<HtmlConfig> {
-        match self.get_deserialized_opt("output.html") {
+        match self
+            .get_deserialized_opt("output.html")
+            .with_context(|| "Parsing configuration [output.html]")
+        {
             Ok(Some(config)) => Some(config),
             Ok(None) => None,
             Err(e) => {
-                utils::log_backtrace(&e.chain_err(|| "Parsing configuration [output.html]"));
+                utils::log_backtrace(&e);
                 None
             }
         }
@@ -208,7 +211,7 @@ impl Config {
                 value
                     .clone()
                     .try_into()
-                    .chain_err(|| "Couldn't deserialize the value")
+                    .with_context(|| "Couldn't deserialize the value")
             })
             .transpose()
     }
@@ -220,8 +223,8 @@ impl Config {
     pub fn set<S: Serialize, I: AsRef<str>>(&mut self, index: I, value: S) -> Result<()> {
         let index = index.as_ref();
 
-        let value =
-            Value::try_from(value).chain_err(|| "Unable to represent the item as a JSON Value")?;
+        let value = Value::try_from(value)
+            .with_context(|| "Unable to represent the item as a JSON Value")?;
 
         if index.starts_with("book.") {
             self.book.update_value(&index[5..], value);