use a distinct error_chain for the tdb submodule

src/errors.rs

@@ -1,9 +1,5 @@
 error_chain!{
-    foreign_links {
-        Io(::std::io::Error);
-        StrFromUtf8(::std::str::Utf8Error);
-        StringFromUtf8(::std::string::FromUtf8Error);
-        StringFromUtf16(::std::string::FromUtf16Error);
+    links {
+        Tdb2Error(::tdb2::errors::Error, ::tdb2::errors::ErrorKind);
     }
-
 }

src/main.rs

@@ -1,3 +1,5 @@
+#![recursion_limit = "1024"]
+
 extern crate chrono;
 extern crate uuid;
 #[macro_use]
@@ -12,12 +14,34 @@ use std::io::stdin;
 
 use errors::*;
 
-quick_main!(run);
+fn main() {
+    if let Err(ref e) = run() {
+        use std::io::Write;
+        let stderr = &mut ::std::io::stderr();
+        let errmsg = "Error writing to stderr";
+
+        writeln!(stderr, "error: {}", e).expect(errmsg);
+
+        for e in e.iter().skip(1) {
+            writeln!(stderr, "caused by: {}", e).expect(errmsg);
+        }
+
+        // The backtrace is not always generated. Try to run this example
+        // with `RUST_BACKTRACE=1`.
+        if let Some(backtrace) = e.backtrace() {
+            writeln!(stderr, "backtrace: {:?}", backtrace).expect(errmsg);
+        }
+
+        ::std::process::exit(1);
+    }
+}
 
 fn run() -> Result<()> {
     let input = stdin();
-    parse(input.lock())?.iter().for_each(|t| {
-        println!("{:?}", t);
-    });
+    parse("<stdin>".to_string(), input.lock())?
+        .iter()
+        .for_each(|t| {
+            println!("{:?}", t);
+        });
     Ok(())
 }

src/tdb2/errors.rs

@@ -0,0 +1,15 @@
+error_chain!{
+    foreign_links {
+        Io(::std::io::Error);
+        StrFromUtf8(::std::str::Utf8Error);
+        StringFromUtf8(::std::string::FromUtf8Error);
+        StringFromUtf16(::std::string::FromUtf16Error);
+    }
+
+    errors {
+        ParseError(filename: String, line: u64) {
+            description("TDB2 parse error"),
+            display("TDB2 parse error at {}:{}", filename, line),
+        }
+    }
+}

src/tdb2/ff4.rs

@@ -2,7 +2,7 @@ use std::str;
 
 use super::pig::Pig;
 use task::{TaskBuilder, Task};
-use errors::*;
+use super::errors::*;
 
 /// Rust implementation of part of utf8_codepoint from Taskwarrior's src/utf8.cpp
 ///

src/tdb2/mod.rs

@@ -1,15 +1,21 @@
+//! TDB2 is Taskwarrior's on-disk database format.  This module implements
+//! support for the data structure as a  compatibility layer.
+
 mod pig;
 mod ff4;
+pub(super) mod errors;
 
 use std::io::BufRead;
 use task::Task;
 use self::ff4::parse_ff4;
-use errors::*;
+use self::errors::*;
 
-pub(super) fn parse(reader: impl BufRead) -> Result<Vec<Task>> {
+pub(super) fn parse(filename: String, reader: impl BufRead) -> Result<Vec<Task>> {
     let mut tasks = vec![];
-    for line in reader.lines() {
-        tasks.push(parse_ff4(&line?)?);
+    for (i, line) in reader.lines().enumerate() {
+        tasks.push(parse_ff4(&line?).chain_err(|| {
+            ErrorKind::ParseError(filename.clone(), i as u64 + 1)
+        })?);
     }
     Ok(tasks)
 }

src/tdb2/pig.rs

@@ -1,7 +1,7 @@
 //! A minimal implementation of the "Pig" parsing utility from the Taskwarrior
 //! source.  This is just enough to parse FF4 lines.
 
-use errors::*;
+use super::errors::*;
 
 pub struct Pig<'a> {
     input: &'a [u8],