Merge pull request #314 from zertosh/add-line-and-col-to-errors

Add line and column to all Errors

8 files changed, 540 insertions, 109 deletions

diff --git a/src/de.rs b/src/de.rs
index 2ec7563..0b7b2cc 100644
--- a/src/de.rs
+++ b/src/de.rs
@@ -29,7 +29,7 @@ where
 {
     match str::from_utf8(bytes) {
         Ok(s) => from_str(s),
-        Err(e) => Err(Error::custom(e.to_string())),
+        Err(e) => Err(Error::custom(None, e.to_string())),
     }
 }
 
@@ -87,6 +87,7 @@ struct ErrorInner {
     kind: ErrorKind,
     line: Option<usize>,
     col: usize,
+    at: Option<usize>,
     message: String,
     key: Vec<String>,
 }
@@ -209,7 +210,7 @@ impl<'de, 'b> de::Deserializer<'de> for &'b mut Deserializer<'de> {
     {
         let mut tables = self.tables()?;
 
-        visitor.visit_map(MapVisitor {
+        let res = visitor.visit_map(MapVisitor {
             values: Vec::new().into_iter(),
             next_value: None,
             depth: 0,
@@ -219,6 +220,17 @@ impl<'de, 'b> de::Deserializer<'de> for &'b mut Deserializer<'de> {
             tables: &mut tables,
             array: false,
             de: self,
+        });
+        res.map_err(|mut err| {
+            // Errors originating from this library (toml), have an offset
+            // attached to them already. Other errors, like those originating
+            // from serde (like "missing field") or from a custom deserializer,
+            // do not have offsets on them. Here, we do a best guess at their
+            // location, by attributing them to the "current table" (the last
+            // item in `tables`).
+            err.fix_offset(|| tables.last().map(|table| table.at));
+            err.fix_linecol(|at| self.to_linecol(at));
+            err
         })
     }
 
@@ -237,14 +249,17 @@ impl<'de, 'b> de::Deserializer<'de> for &'b mut Deserializer<'de> {
             E::String(val) => visitor.visit_enum(val.into_deserializer()),
             E::InlineTable(values) => {
                 if values.len() != 1 {
-                    Err(Error::from_kind(ErrorKind::Wanted {
-                        expected: "exactly 1 element",
-                        found: if values.is_empty() {
-                            "zero elements"
-                        } else {
-                            "more than 1 element"
+                    Err(Error::from_kind(
+                        Some(value.start),
+                        ErrorKind::Wanted {
+                            expected: "exactly 1 element",
+                            found: if values.is_empty() {
+                                "zero elements"
+                            } else {
+                                "more than 1 element"
+                            },
                         },
-                    }))
+                    ))
                 } else {
                     visitor.visit_enum(InlineTableDeserializer {
                         values: values.into_iter(),
@@ -256,10 +271,13 @@ impl<'de, 'b> de::Deserializer<'de> for &'b mut Deserializer<'de> {
                 name: name.expect("Expected table header to be passed."),
                 value: value,
             }),
-            e @ _ => Err(Error::from_kind(ErrorKind::Wanted {
-                expected: "string or table",
-                found: e.type_name(),
-            })),
+            e @ _ => Err(Error::from_kind(
+                Some(value.start),
+                ErrorKind::Wanted {
+                    expected: "string or table",
+                    found: e.type_name(),
+                },
+            )),
         }
     }
 
@@ -556,7 +574,8 @@ impl<'de> de::Deserializer<'de> for ValueDeserializer<'de> {
     where
         V: de::Visitor<'de>,
     {
-        match self.value.e {
+        let start = self.value.start;
+        let res = match self.value.e {
             E::Integer(i) => visitor.visit_i64(i),
             E::Boolean(b) => visitor.visit_bool(b),
             E::Float(f) => visitor.visit_f64(f),
@@ -578,7 +597,12 @@ impl<'de> de::Deserializer<'de> for ValueDeserializer<'de> {
                     next_value: None,
                 })
             }
-        }
+        };
+        res.map_err(|mut err| {
+            // Attribute the error to whatever value returned the error.
+            err.fix_offset(|| Some(start));
+            err
+        })
     }
 
     fn deserialize_struct<V>(
@@ -615,13 +639,16 @@ impl<'de> de::Deserializer<'de> for ValueDeserializer<'de> {
                         .collect::<Vec<Cow<'de, str>>>();
 
                     if !extra_fields.is_empty() {
-                        return Err(Error::from_kind(ErrorKind::UnexpectedKeys {
-                            keys: extra_fields
-                                .iter()
-                                .map(|k| k.to_string())
-                                .collect::<Vec<_>>(),
-                            available: fields,
-                        }));
+                        return Err(Error::from_kind(
+                            Some(self.value.start),
+                            ErrorKind::UnexpectedKeys {
+                                keys: extra_fields
+                                    .iter()
+                                    .map(|k| k.to_string())
+                                    .collect::<Vec<_>>(),
+                                available: fields,
+                            },
+                        ));
                     }
                 }
                 _ => {}
@@ -664,14 +691,17 @@ impl<'de> de::Deserializer<'de> for ValueDeserializer<'de> {
             E::String(val) => visitor.visit_enum(val.into_deserializer()),
             E::InlineTable(values) => {
                 if values.len() != 1 {
-                    Err(Error::from_kind(ErrorKind::Wanted {
-                        expected: "exactly 1 element",
-                        found: if values.is_empty() {
-                            "zero elements"
-                        } else {
-                            "more than 1 element"
+                    Err(Error::from_kind(
+                        Some(self.value.start),
+                        ErrorKind::Wanted {
+                            expected: "exactly 1 element",
+                            found: if values.is_empty() {
+                                "zero elements"
+                            } else {
+                                "more than 1 element"
+                            },
                         },
-                    }))
+                    ))
                 } else {
                     visitor.visit_enum(InlineTableDeserializer {
                         values: values.into_iter(),
@@ -679,10 +709,13 @@ impl<'de> de::Deserializer<'de> for ValueDeserializer<'de> {
                     })
                 }
             }
-            e @ _ => Err(Error::from_kind(ErrorKind::Wanted {
-                expected: "string or inline table",
-                found: e.type_name(),
-            })),
+            e @ _ => Err(Error::from_kind(
+                Some(self.value.start),
+                ErrorKind::Wanted {
+                    expected: "string or inline table",
+                    found: e.type_name(),
+                },
+            )),
         }
     }
 
@@ -860,10 +893,13 @@ impl<'de> de::EnumAccess<'de> for InlineTableDeserializer<'de> {
         let (key, value) = match self.values.next() {
             Some(pair) => pair,
             None => {
-                return Err(Error::from_kind(ErrorKind::Wanted {
-                    expected: "table with exactly 1 entry",
-                    found: "empty table",
-                }))
+                return Err(Error::from_kind(
+                    None, // FIXME: How do we get an offset here?
+                    ErrorKind::Wanted {
+                        expected: "table with exactly 1 entry",
+                        found: "empty table",
+                    },
+                ));
             }
         };
 
@@ -886,13 +922,19 @@ impl<'de> de::VariantAccess<'de> for TableEnumDeserializer<'de> {
                 if values.len() == 0 {
                     Ok(())
                 } else {
-                    Err(Error::from_kind(ErrorKind::ExpectedEmptyTable))
+                    Err(Error::from_kind(
+                        Some(self.value.start),
+                        ErrorKind::ExpectedEmptyTable,
+                    ))
                 }
             }
-            e @ _ => Err(Error::from_kind(ErrorKind::Wanted {
-                expected: "table",
-                found: e.type_name(),
-            })),
+            e @ _ => Err(Error::from_kind(
+                Some(self.value.start),
+                ErrorKind::Wanted {
+                    expected: "table",
+                    found: e.type_name(),
+                },
+            )),
         }
     }
 
@@ -914,10 +956,13 @@ impl<'de> de::VariantAccess<'de> for TableEnumDeserializer<'de> {
                     .enumerate()
                     .map(|(index, (key, value))| match key.parse::<usize>() {
                         Ok(key_index) if key_index == index => Ok(value),
-                        Ok(_) | Err(_) => Err(Error::from_kind(ErrorKind::ExpectedTupleIndex {
-                            expected: index,
-                            found: key.to_string(),
-                        })),
+                        Ok(_) | Err(_) => Err(Error::from_kind(
+                            Some(value.start),
+                            ErrorKind::ExpectedTupleIndex {
+                                expected: index,
+                                found: key.to_string(),
+                            },
+                        )),
                     })
                     // Fold all values into a `Vec`, or return the first error.
                     .fold(Ok(Vec::with_capacity(len)), |result, value_result| {
@@ -941,13 +986,19 @@ impl<'de> de::VariantAccess<'de> for TableEnumDeserializer<'de> {
                         visitor,
                     )
                 } else {
-                    Err(Error::from_kind(ErrorKind::ExpectedTuple(len)))
+                    Err(Error::from_kind(
+                        Some(self.value.start),
+                        ErrorKind::ExpectedTuple(len),
+                    ))
                 }
             }
-            e @ _ => Err(Error::from_kind(ErrorKind::Wanted {
-                expected: "table",
-                found: e.type_name(),
-            })),
+            e @ _ => Err(Error::from_kind(
+                Some(self.value.start),
+                ErrorKind::Wanted {
+                    expected: "table",
+                    found: e.type_name(),
+                },
+            )),
         }
     }
 
@@ -1195,17 +1246,20 @@ impl<'a> Deserializer<'a> {
     /// structures (tuple, newtype, struct) must be represented as a table.
     fn string_or_table(&mut self) -> Result<(Value<'a>, Option<Cow<'a, str>>), Error> {
         match self.peek()? {
-            Some((_, Token::LeftBracket)) => {
+            Some((span, Token::LeftBracket)) => {
                 let tables = self.tables()?;
                 if tables.len() != 1 {
-                    return Err(Error::from_kind(ErrorKind::Wanted {
-                        expected: "exactly 1 table",
-                        found: if tables.is_empty() {
-                            "zero tables"
-                        } else {
-                            "more than 1 table"
+                    return Err(Error::from_kind(
+                        Some(span.start),
+                        ErrorKind::Wanted {
+                            expected: "exactly 1 table",
+                            found: if tables.is_empty() {
+                                "zero tables"
+                            } else {
+                                "more than 1 table"
+                            },
                         },
-                    }));
+                    ));
                 }
 
                 let table = tables
@@ -1710,10 +1764,8 @@ impl<'a> Deserializer<'a> {
     }
 
     fn error(&self, at: usize, kind: ErrorKind) -> Error {
-        let mut err = Error::from_kind(kind);
-        let (line, col) = self.to_linecol(at);
-        err.inner.line = Some(line);
-        err.inner.col = col;
+        let mut err = Error::from_kind(Some(at), kind);
+        err.fix_linecol(|at| self.to_linecol(at));
         err
     }
 
@@ -1740,24 +1792,26 @@ impl Error {
         self.inner.line.map(|line| (line, self.inner.col))
     }
 
-    fn from_kind(kind: ErrorKind) -> Error {
+    fn from_kind(at: Option<usize>, kind: ErrorKind) -> Error {
         Error {
             inner: Box::new(ErrorInner {
                 kind: kind,
                 line: None,
                 col: 0,
+                at,
                 message: String::new(),
                 key: Vec::new(),
             }),
         }
     }
 
-    fn custom(s: String) -> Error {
+    fn custom(at: Option<usize>, s: String) -> Error {
         Error {
             inner: Box::new(ErrorInner {
                 kind: ErrorKind::Custom,
                 line: None,
                 col: 0,
+                at,
                 message: s,
                 key: Vec::new(),
             }),
@@ -1770,6 +1824,28 @@ impl Error {
     pub fn add_key_context(&mut self, key: &str) {
         self.inner.key.insert(0, key.to_string());
     }
+
+    fn fix_offset<F>(&mut self, f: F) -> ()
+    where
+        F: FnOnce() -> Option<usize>,
+    {
+        // An existing offset is always better positioned than anything we
+        // might want to add later.
+        if self.inner.at.is_none() {
+            self.inner.at = f();
+        }
+    }
+
+    fn fix_linecol<F>(&mut self, f: F) -> ()
+    where
+        F: FnOnce(usize) -> (usize, usize),
+    {
+        if let Some(at) = self.inner.at {
+            let (line, col) = f(at);
+            self.inner.line = Some(line);
+            self.inner.col = col;
+        }
+    }
 }
 
 impl fmt::Display for Error {
@@ -1885,7 +1961,7 @@ impl error::Error for Error {
 
 impl de::Error for Error {
     fn custom<T: fmt::Display>(msg: T) -> Error {
-        Error::custom(msg.to_string())
+        Error::custom(None, msg.to_string())
     }
 }
 
diff --git a/test-suite/Cargo.toml b/test-suite/Cargo.toml
index 4f4db16..9f500b3 100644
--- a/test-suite/Cargo.toml
+++ b/test-suite/Cargo.toml
@@ -7,6 +7,6 @@ edition = "2018"
 
 [dev-dependencies]
 toml = { path = ".." }
-serde = "1.0"
+serde = { version = "1.0", features = ["derive"] }
 serde_derive = "1.0"
 serde_json = "1.0"
diff --git a/test-suite/tests/datetime.rs b/test-suite/tests/datetime.rs
index 4855f54..74b5939 100644
--- a/test-suite/tests/datetime.rs
+++ b/test-suite/tests/datetime.rs
@@ -42,75 +42,93 @@ fn times() {
 
 #[test]
 fn bad_times() {
-    bad!("foo = 199-09-09", "failed to parse datetime for key `foo`");
-    bad!("foo = 199709-09", "failed to parse datetime for key `foo`");
-    bad!("foo = 1997-9-09", "failed to parse datetime for key `foo`");
-    bad!("foo = 1997-09-9", "failed to parse datetime for key `foo`");
+    bad!(
+        "foo = 199-09-09",
+        "failed to parse datetime for key `foo` at line 1 column 7"
+    );
+    bad!(
+        "foo = 199709-09",
+        "failed to parse datetime for key `foo` at line 1 column 7"
+    );
+    bad!(
+        "foo = 1997-9-09",
+        "failed to parse datetime for key `foo` at line 1 column 7"
+    );
+    bad!(
+        "foo = 1997-09-9",
+        "failed to parse datetime for key `foo` at line 1 column 7"
+    );
     bad!(
         "foo = 1997-09-0909:09:09",
-        "failed to parse datetime for key `foo`"
+        "failed to parse datetime for key `foo` at line 1 column 7"
     );
     bad!(
         "foo = 1997-09-09T09:09:09.",
         "invalid date at line 1 column 7"
     );
-    bad!("foo = T", "failed to parse datetime for key `foo`");
+    bad!(
+        "foo = T",
+        "failed to parse datetime for key `foo` at line 1 column 7"
+    );
     bad!(
         "foo = T.",
         "expected newline, found a period at line 1 column 8"
     );
-    bad!("foo = TZ", "failed to parse datetime for key `foo`");
+    bad!(
+        "foo = TZ",
+        "failed to parse datetime for key `foo` at line 1 column 7"
+    );
     bad!(
         "foo = 1997-09-09T09:09:09.09+",
         "invalid date at line 1 column 7"
     );
     bad!(
         "foo = 1997-09-09T09:09:09.09+09",
-        "failed to parse datetime for key `foo`"
+        "failed to parse datetime for key `foo` at line 1 column 7"
     );
     bad!(
         "foo = 1997-09-09T09:09:09.09+09:9",
-        "failed to parse datetime for key `foo`"
+        "failed to parse datetime for key `foo` at line 1 column 7"
     );
     bad!(
         "foo = 1997-09-09T09:09:09.09+0909",
-        "failed to parse datetime for key `foo`"
+        "failed to parse datetime for key `foo` at line 1 column 7"
     );
     bad!(
         "foo = 1997-09-09T09:09:09.09-",
-        "failed to parse datetime for key `foo`"
+        "failed to parse datetime for key `foo` at line 1 column 7"
     );
     bad!(
         "foo = 1997-09-09T09:09:09.09-09",
-        "failed to parse datetime for key `foo`"
+        "failed to parse datetime for key `foo` at line 1 column 7"
     );
     bad!(
         "foo = 1997-09-09T09:09:09.09-09:9",
-        "failed to parse datetime for key `foo`"
+        "failed to parse datetime for key `foo` at line 1 column 7"
     );
     bad!(
         "foo = 1997-09-09T09:09:09.09-0909",
-        "failed to parse datetime for key `foo`"
+        "failed to parse datetime for key `foo` at line 1 column 7"
     );
 
     bad!(
         "foo = 1997-00-09T09:09:09.09Z",
-        "failed to parse datetime for key `foo`"
+        "failed to parse datetime for key `foo` at line 1 column 7"
     );
     bad!(
         "foo = 1997-09-00T09:09:09.09Z",
-        "failed to parse datetime for key `foo`"
+        "failed to parse datetime for key `foo` at line 1 column 7"
     );
     bad!(
         "foo = 1997-09-09T30:09:09.09Z",
-        "failed to parse datetime for key `foo`"
+        "failed to parse datetime for key `foo` at line 1 column 7"
     );
     bad!(
         "foo = 1997-09-09T12:69:09.09Z",
-        "failed to parse datetime for key `foo`"
+        "failed to parse datetime for key `foo` at line 1 column 7"
     );
     bad!(
         "foo = 1997-09-09T12:09:69.09Z",
-        "failed to parse datetime for key `foo`"
+        "failed to parse datetime for key `foo` at line 1 column 7"
     );
 }
diff --git a/test-suite/tests/de-errors.rs b/test-suite/tests/de-errors.rs
new file mode 100644
index 0000000..7cceb7b
--- /dev/null
+++ b/test-suite/tests/de-errors.rs
@@ -0,0 +1,325 @@
+extern crate serde;
+extern crate toml;
+
+use serde::{de, Deserialize};
+use std::fmt;
+
+macro_rules! bad {
+    ($toml:expr, $ty:ty, $msg:expr) => {
+        match toml::from_str::<$ty>($toml) {
+            Ok(s) => panic!("parsed to: {:#?}", s),
+            Err(e) => assert_eq!(e.to_string(), $msg),
+        }
+    };
+}
+
+#[derive(Debug, Deserialize, PartialEq)]
+struct Parent<T> {
+    p_a: T,
+    p_b: Vec<Child<T>>,
+}
+
+#[derive(Debug, Deserialize, PartialEq)]
+#[serde(deny_unknown_fields)]
+struct Child<T> {
+    c_a: T,
+    c_b: T,
+}
+
+#[derive(Debug, PartialEq)]
+enum CasedString {
+    Lowercase(String),
+    Uppercase(String),
+}
+
+impl<'de> de::Deserialize<'de> for CasedString {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: de::Deserializer<'de>,
+    {
+        struct CasedStringVisitor;
+
+        impl<'de> de::Visitor<'de> for CasedStringVisitor {
+            type Value = CasedString;
+
+            fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+                formatter.write_str("a string")
+            }
+
+            fn visit_str<E>(self, s: &str) -> Result<Self::Value, E>
+            where
+                E: de::Error,
+            {
+                if s.is_empty() {
+                    Err(de::Error::invalid_length(0, &"a non-empty string"))
+                } else if s.chars().all(|x| x.is_ascii_lowercase()) {
+                    Ok(CasedString::Lowercase(s.to_string()))
+                } else if s.chars().all(|x| x.is_ascii_uppercase()) {
+                    Ok(CasedString::Uppercase(s.to_string()))
+                } else {
+                    Err(de::Error::invalid_value(
+                        de::Unexpected::Str(s),
+                        &"all lowercase or all uppercase",
+                    ))
+                }
+            }
+        }
+
+        deserializer.deserialize_any(CasedStringVisitor)
+    }
+}
+
+#[test]
+fn custom_errors() {
+    toml::from_str::<Parent<CasedString>>(
+        "
+            p_a = 'a'
+            p_b = [{c_a = 'a', c_b = 'c'}]
+        ",
+    )
+    .unwrap();
+
+    // Custom error at p_b value.
+    bad!(
+        "
+            p_a = ''
+                # ^
+        ",
+        Parent<CasedString>,
+        "invalid length 0, expected a non-empty string for key `p_a` at line 2 column 19"
+    );
+
+    // Missing field in table.
+    bad!(
+        "
+            p_a = 'a'
+          # ^
+        ",
+        Parent<CasedString>,
+        "missing field `p_b` at line 1 column 1"
+    );
+
+    // Invalid type in p_b.
+    bad!(
+        "
+            p_a = 'a'
+            p_b = 1
+                # ^
+        ",
+        Parent<CasedString>,
+        "invalid type: integer `1`, expected a sequence for key `p_b` at line 3 column 19"
+    );
+
+    // Sub-table in Vec is missing a field.
+    bad!(
+        "
+            p_a = 'a'
+            p_b = [
+                {c_a = 'a'}
+              # ^
+            ]
+        ",
+        Parent<CasedString>,
+        "missing field `c_b` for key `p_b` at line 4 column 17"
+    );
+
+    // Sub-table in Vec has a field with a bad value.
+    bad!(
+        "
+            p_a = 'a'
+            p_b = [
+                {c_a = 'a', c_b = '*'}
+                                # ^
+            ]
+        ",
+        Parent<CasedString>,
+        "invalid value: string \"*\", expected all lowercase or all uppercase for key `p_b` at line 4 column 35"
+    );
+
+    // Sub-table in Vec is missing a field.
+    bad!(
+        "
+            p_a = 'a'
+            p_b = [
+                {c_a = 'a', c_b = 'b'},
+                {c_a = 'aa'}
+              # ^
+            ]
+        ",
+        Parent<CasedString>,
+        "missing field `c_b` for key `p_b` at line 5 column 17"
+    );
+
+    // Sub-table in the middle of a Vec is missing a field.
+    bad!(
+        "
+            p_a = 'a'
+            p_b = [
+                {c_a = 'a', c_b = 'b'},
+                {c_a = 'aa'},
+              # ^
+                {c_a = 'aaa', c_b = 'bbb'},
+            ]
+        ",
+        Parent<CasedString>,
+        "missing field `c_b` for key `p_b` at line 5 column 17"
+    );
+
+    // Sub-table in the middle of a Vec has a field with a bad value.
+    bad!(
+        "
+            p_a = 'a'
+            p_b = [
+                {c_a = 'a', c_b = 'b'},
+                {c_a = 'aa', c_b = 1},
+                                 # ^
+                {c_a = 'aaa', c_b = 'bbb'},
+            ]
+        ",
+        Parent<CasedString>,
+        "invalid type: integer `1`, expected a string for key `p_b` at line 5 column 36"
+    );
+
+    // Sub-table in the middle of a Vec has an extra field.
+    // FIXME: This location could be better.
+    bad!(
+        "
+            p_a = 'a'
+            p_b = [
+                {c_a = 'a', c_b = 'b'},
+                {c_a = 'aa', c_b = 'bb', c_d = 'd'},
+              # ^
+                {c_a = 'aaa', c_b = 'bbb'},
+                {c_a = 'aaaa', c_b = 'bbbb'},
+            ]
+        ",
+        Parent<CasedString>,
+        "unknown field `c_d`, expected `c_a` or `c_b` for key `p_b` at line 5 column 17"
+    );
+
+    // Sub-table in the middle of a Vec is missing a field.
+    // FIXME: This location is pretty off.
+    bad!(
+        "
+            p_a = 'a'
+            [[p_b]]
+            c_a = 'a'
+            c_b = 'b'
+            [[p_b]]
+            c_a = 'aa'
+            # c_b = 'bb' # <- missing field
+            [[p_b]]
+            c_a = 'aaa'
+            c_b = 'bbb'
+            [[p_b]]
+          # ^
+            c_a = 'aaaa'
+            c_b = 'bbbb'
+        ",
+        Parent<CasedString>,
+        "missing field `c_b` for key `p_b` at line 12 column 13"
+    );
+
+    // Sub-table in the middle of a Vec has a field with a bad value.
+    bad!(
+        "
+            p_a = 'a'
+            [[p_b]]
+            c_a = 'a'
+            c_b = 'b'
+            [[p_b]]
+            c_a = 'aa'
+            c_b = '*'
+                # ^
+            [[p_b]]
+            c_a = 'aaa'
+            c_b = 'bbb'
+        ",
+        Parent<CasedString>,
+        "invalid value: string \"*\", expected all lowercase or all uppercase for key `p_b.c_b` at line 8 column 19"
+    );
+
+    // Sub-table in the middle of a Vec has an extra field.
+    // FIXME: This location is pretty off.
+    bad!(
+        "
+            p_a = 'a'
+            [[p_b]]
+            c_a = 'a'
+            c_b = 'b'
+            [[p_b]]
+            c_a = 'aa'
+            c_d = 'dd' # unknown field
+            [[p_b]]
+            c_a = 'aaa'
+            c_b = 'bbb'
+            [[p_b]]
+          # ^
+            c_a = 'aaaa'
+            c_b = 'bbbb'
+        ",
+        Parent<CasedString>,
+        "unknown field `c_d`, expected `c_a` or `c_b` for key `p_b` at line 12 column 13"
+    );
+}
+
+#[test]
+fn serde_derive_deserialize_errors() {
+    bad!(
+        "
+            p_a = ''
+          # ^
+        ",
+        Parent<String>,
+        "missing field `p_b` at line 1 column 1"
+    );
+
+    bad!(
+        "
+            p_a = ''
+            p_b = [
+                {c_a = ''}
+              # ^
+            ]
+        ",
+        Parent<String>,
+        "missing field `c_b` for key `p_b` at line 4 column 17"
+    );
+
+    bad!(
+        "
+            p_a = ''
+            p_b = [
+                {c_a = '', c_b = 1}
+                               # ^
+            ]
+        ",
+        Parent<String>,
+        "invalid type: integer `1`, expected a string for key `p_b` at line 4 column 34"
+    );
+
+    // FIXME: This location could be better.
+    bad!(
+        "
+            p_a = ''
+            p_b = [
+                {c_a = '', c_b = '', c_d = ''},
+              # ^
+            ]
+        ",
+        Parent<String>,
+        "unknown field `c_d`, expected `c_a` or `c_b` for key `p_b` at line 4 column 17"
+    );
+
+    bad!(
+        "
+            p_a = 'a'
+            p_b = [
+                {c_a = '', c_b = 1, c_d = ''},
+                               # ^
+            ]
+        ",
+        Parent<String>,
+        "invalid type: integer `1`, expected a string for key `p_b` at line 4 column 34"
+    );
+}
diff --git a/test-suite/tests/invalid-misc.rs b/test-suite/tests/invalid-misc.rs
index f18012a..cea0801 100644
--- a/test-suite/tests/invalid-misc.rs
+++ b/test-suite/tests/invalid-misc.rs
@@ -27,14 +27,17 @@ fn bad() {
     );
 
     bad!("a = -0x1", "invalid number at line 1 column 5");
-    bad!("a = 0x-1", "failed to parse datetime for key `a`");
+    bad!(
+        "a = 0x-1",
+        "failed to parse datetime for key `a` at line 1 column 5"
+    );
 
     // Dotted keys.
     bad!(
         "a.b.c = 1
          a.b = 2
         ",
-        "duplicate key: `b` for key `a`"
+        "duplicate key: `b` for key `a` at line 1 column 9"
     );
     bad!(
         "a = 1
diff --git a/test-suite/tests/invalid.rs b/test-suite/tests/invalid.rs
index bfde2d4..3312629 100644
--- a/test-suite/tests/invalid.rs
+++ b/test-suite/tests/invalid.rs
@@ -32,7 +32,7 @@ test!(
 test!(
     datetime_malformed_no_leads,
     include_str!("invalid/datetime-malformed-no-leads.toml"),
-    "failed to parse datetime for key `no-leads`"
+    "failed to parse datetime for key `no-leads` at line 1 column 12"
 );
 test!(
     datetime_malformed_no_secs,
@@ -42,22 +42,22 @@ test!(
 test!(
     datetime_malformed_no_t,
     include_str!("invalid/datetime-malformed-no-t.toml"),
-    "failed to parse datetime for key `no-t`"
+    "failed to parse datetime for key `no-t` at line 1 column 8"
 );
 test!(
     datetime_malformed_with_milli,
     include_str!("invalid/datetime-malformed-with-milli.toml"),
-    "failed to parse datetime for key `with-milli`"
+    "failed to parse datetime for key `with-milli` at line 1 column 14"
 );
 test!(
     duplicate_key_table,
     include_str!("invalid/duplicate-key-table.toml"),
-    "duplicate key: `type` for key `fruit`"
+    "duplicate key: `type` for key `fruit` at line 4 column 1"
 );
 test!(
     duplicate_keys,
     include_str!("invalid/duplicate-keys.toml"),
-    "duplicate key: `dupe`"
+    "duplicate key: `dupe` at line 1 column 1"
 );
 test!(
     duplicate_table,
diff --git a/test-suite/tests/parser.rs b/test-suite/tests/parser.rs
index 1a684c5..012bd65 100644
--- a/test-suite/tests/parser.rs
+++ b/test-suite/tests/parser.rs
@@ -453,7 +453,10 @@ fn inline_tables() {
         "a = {,}",
         "expected a table key, found a comma at line 1 column 6"
     );
-    bad!("a = {a=1,a=1}", "duplicate key: `a` for key `a`");
+    bad!(
+        "a = {a=1,a=1}",
+        "duplicate key: `a` for key `a` at line 1 column 5"
+    );
     bad!(
         "a = {\n}",
         "expected a table key, found a newline at line 1 column 6"
@@ -533,9 +536,15 @@ fn booleans() {
     let table = "foo = false".parse::<Value>().unwrap();
     assert_eq!(table["foo"].as_bool(), Some(false));
 
-    bad!("foo = true2", "failed to parse datetime for key `foo`");
+    bad!(
+        "foo = true2",
+        "failed to parse datetime for key `foo` at line 1 column 7"
+    );
     bad!("foo = false2", "invalid number at line 1 column 7");
-    bad!("foo = t1", "failed to parse datetime for key `foo`");
+    bad!(
+        "foo = t1",
+        "failed to parse datetime for key `foo` at line 1 column 7"
+    );
     bad!("foo = f2", "invalid number at line 1 column 7");
 }
 
@@ -547,28 +556,28 @@ fn bad_nesting() {
         [[a]]
         b = 5
         ",
-        "duplicate key: `a`"
+        "duplicate key: `a` at line 3 column 9"
     );
     bad!(
         "
         a = 1
         [a.b]
         ",
-        "duplicate key: `a`"
+        "duplicate key: `a` at line 3 column 9"
     );
     bad!(
         "
         a = []
         [a.b]
         ",
-        "duplicate key: `a`"
+        "duplicate key: `a` at line 3 column 9"
     );
     bad!(
         "
         a = []
         [[a.b]]
         ",
-        "duplicate key: `a`"
+        "duplicate key: `a` at line 3 column 9"
     );
     bad!(
         "
@@ -577,7 +586,7 @@ fn bad_nesting() {
         [a.b]
         c = 2
         ",
-        "duplicate key: `b` for key `a`"
+        "duplicate key: `b` for key `a` at line 4 column 9"
     );
 }
 
@@ -608,7 +617,7 @@ fn bad_table_redefine() {
         b = {}
         [a.b]
         ",
-        "duplicate key: `b` for key `a`"
+        "duplicate key: `b` for key `a` at line 4 column 9"
     );
 
     bad!(
@@ -637,23 +646,23 @@ fn datetimes() {
     t!("2016-09-09T09:09:09.123456789-02:00");
     bad!(
         "foo = 2016-09-09T09:09:09.Z",
-        "failed to parse datetime for key `foo`"
+        "failed to parse datetime for key `foo` at line 1 column 7"
     );
     bad!(
         "foo = 2016-9-09T09:09:09Z",
-        "failed to parse datetime for key `foo`"
+        "failed to parse datetime for key `foo` at line 1 column 7"
     );
     bad!(
         "foo = 2016-09-09T09:09:09+2:00",
-        "failed to parse datetime for key `foo`"
+        "failed to parse datetime for key `foo` at line 1 column 7"
     );
     bad!(
         "foo = 2016-09-09T09:09:09-2:00",
-        "failed to parse datetime for key `foo`"
+        "failed to parse datetime for key `foo` at line 1 column 7"
     );
     bad!(
         "foo = 2016-09-09T09:09:09Z-2:00",
-        "failed to parse datetime for key `foo`"
+        "failed to parse datetime for key `foo` at line 1 column 7"
     );
 }
 
diff --git a/test-suite/tests/serde.rs b/test-suite/tests/serde.rs
index 95b8bc4..56172bd 100644
--- a/test-suite/tests/serde.rs
+++ b/test-suite/tests/serde.rs
@@ -273,7 +273,7 @@ fn type_errors() {
         Table(map! {
             bar: Value::String("a".to_string())
         }),
-        "invalid type: string \"a\", expected isize for key `bar`",
+        "invalid type: string \"a\", expected isize for key `bar` at line 1 column 7",
         "invalid type: string \"a\", expected isize for key `bar`"
     }
 
@@ -290,7 +290,7 @@ fn type_errors() {
                 bar: Value::String("a".to_string())
             })
         }),
-        "invalid type: string \"a\", expected isize for key `foo.bar`",
+        "invalid type: string \"a\", expected isize for key `foo.bar` at line 2 column 7",
         "invalid type: string \"a\", expected isize for key `foo.bar`"
     }
 }