fix(error): Clean up duplicate key error

- We specify which table in a case where we knew the name
- For inline tables, instead of saying `<unknown> table`, we just don't
  say anything (making the parser stateful to show table didn't seem
  worth it at this time).
- We now say `document root` instead of `'[]' table`
- We no longer include `[]` (which was wrong for array of tables)

We also share the rendering logic between the different paths.

Fixes #251

src/parser/document.rs

@@ -159,7 +159,7 @@ impl TomlParser {
         if mixed_table_types {
             return Err(CustomError::DuplicateKey {
                 key: kv.key.get().into(),
-                table: "<unknown>".into(), // TODO: get actual table name
+                table: None,
             });
         }
 
@@ -170,7 +170,7 @@ impl TomlParser {
         if duplicate_key {
             return Err(CustomError::DuplicateKey {
                 key: key.as_str().into(),
-                table: "<unknown>".into(), // TODO: get actual table name
+                table: Some(self.current_table_path.clone()),
             });
         }
 

src/parser/errors.rs

@@ -1,6 +1,8 @@
+use crate::Key;
 use combine::easy::Errors as ParseError;
 use combine::stream::easy::Error;
 use combine::stream::position::SourcePosition;
+use itertools::Itertools;
 use std::error::Error as StdError;
 use std::fmt::{Display, Formatter, Result};
 
@@ -233,7 +235,10 @@ mod test_translate_position {
 
 #[derive(Debug, Clone)]
 pub(crate) enum CustomError {
-    DuplicateKey { key: String, table: String },
+    DuplicateKey {
+        key: String,
+        table: Option<Vec<Key>>,
+    },
     InvalidHexEscape(u32),
     UnparsedLine,
     OutOfRange,
@@ -247,11 +252,20 @@ impl StdError for CustomError {
 
 impl Display for CustomError {
     fn fmt(&self, f: &mut Formatter<'_>) -> Result {
-        match *self {
-            CustomError::DuplicateKey { ref key, ref table } => {
-                writeln!(f, "Duplicate key `{}` in `{}` table", key, table)
+        match self {
+            CustomError::DuplicateKey { key, table } => {
+                if let Some(table) = table {
+                    if table.is_empty() {
+                        writeln!(f, "Duplicate key `{}` in document root", key)
+                    } else {
+                        let path = table.iter().join(".");
+                        writeln!(f, "Duplicate key `{}` in table `{}`", key, path)
+                    }
+                } else {
+                    writeln!(f, "Duplicate key `{}`", key)
+                }
             }
-            CustomError::InvalidHexEscape(ref h) => {
+            CustomError::InvalidHexEscape(h) => {
                 writeln!(f, "Invalid hex escape code: {:x} ", h)
             }
             CustomError::UnparsedLine => writeln!(f, "Could not parse the line"),

src/parser/inline_table.rs

@@ -35,7 +35,7 @@ fn table_from_pairs(
         if duplicate_key {
             return Err(CustomError::DuplicateKey {
                 key: key.as_str().into(),
-                table: "inline".into(),
+                table: None,
             });
         }
     }

src/parser/table.rs

@@ -9,7 +9,6 @@ use combine::parser::byte::byte;
 use combine::parser::range::range;
 use combine::stream::RangeStream;
 use combine::*;
-use itertools::Itertools;
 use std::cell::RefCell;
 use std::mem;
 // https://github.com/rust-lang/rust/issues/41358
@@ -71,13 +70,9 @@ parser! {
 
 pub(crate) fn duplicate_key(path: &[Key], i: usize) -> CustomError {
     assert!(i < path.len());
-    let header = path[..i]
-        .iter()
-        .map(|k| k.to_repr().as_ref().as_raw().to_owned())
-        .join(".");
     CustomError::DuplicateKey {
         key: path[i].to_repr().as_ref().as_raw().into(),
-        table: format!("[{}]", header),
+        table: Some(path[..i].to_vec()),
     }
 }
 

tests/fixtures/invalid/duplicate-key-dotted-into-std.stderr

@@ -2,5 +2,5 @@ TOML parse error at line 5, column 1
   |
 5 | apple.color = "red"
   | ^
-Duplicate key `color` in `<unknown>` table
+Duplicate key `color`
 

tests/fixtures/invalid/duplicate-key-std-into-dotted.stderr

@@ -2,5 +2,5 @@ TOML parse error at line 6, column 1
   |
 6 | size = "small"
   | ^
-Duplicate key `size` in `<unknown>` table
+Duplicate key `size`
 

tests/fixtures/invalid/duplicate-key-table.stderr

@@ -2,6 +2,6 @@ TOML parse error at line 4, column 1
   |
 4 | [fruit.type]
   | ^
-Duplicate key `type` in `[fruit]` table
+Duplicate key `type` in table `fruit`
 
 While parsing a Table Header

tests/fixtures/invalid/duplicate-keys-cargo.stderr

@@ -0,0 +1,6 @@
+TOML parse error at line 7, column 1
+  |
+7 | categories = ["algorithms"]
+  | ^
+Duplicate key `categories` in table `project`
+

tests/fixtures/invalid/duplicate-keys-cargo.toml

@@ -0,0 +1,11 @@
+[project]
+
+name = "dep1"
+version = "0.5.0"
+authors = ["[email protected]"]
+categories = ["algorithms"]
+categories = ["algorithms"]
+
+[lib]
+
+name = "dep1"

tests/fixtures/invalid/duplicate-keys.stderr

@@ -2,5 +2,5 @@ TOML parse error at line 2, column 1
   |
 2 | dupe = true
   | ^
-Duplicate key `dupe` in `<unknown>` table
+Duplicate key `dupe` in document root
 

tests/fixtures/invalid/duplicate-tables.stderr

@@ -2,6 +2,6 @@ TOML parse error at line 2, column 1
   |
 2 | [a]
   | ^
-Duplicate key `a` in `[]` table
+Duplicate key `a` in document root
 
 While parsing a Table Header

tests/fixtures/invalid/table-array-implicit.stderr

@@ -2,6 +2,6 @@ TOML parse error at line 13, column 1
    |
 13 | [[albums]]
    | ^
-Duplicate key `albums` in `[]` table
+Duplicate key `albums` in document root
 
 While parsing a Table Header