Group imports consistently

This corresponds to:

$ cargo +nightly fmt -- --config group_imports=StdExternalCrate

Since this option is only available on nightly, I'm not adding a
rustfmt.toml to enforce this, just doing it as a one-off run.

build.rs

@@ -6,8 +6,9 @@
 // body for readability.
 #![allow(clippy::if_same_then_else)]
 
-use rayon::prelude::*;
 use std::{path::PathBuf, process::Command};
+
+use rayon::prelude::*;
 use version_check as rustc;
 
 struct TreeSitterParser {

src/diff/dijkstra.rs

@@ -3,15 +3,16 @@
 
 use std::{cmp::Reverse, env};
 
+use bumpalo::Bump;
+use itertools::Itertools;
+use radix_heap::RadixHeapMap;
+
 use crate::{
     diff::changes::ChangeMap,
     diff::graph::{populate_change_map, set_neighbours, Edge, Vertex},
     hash::DftHashMap,
     parse::syntax::Syntax,
 };
-use bumpalo::Bump;
-use itertools::Itertools;
-use radix_heap::RadixHeapMap;
 
 #[derive(Debug)]
 pub struct ExceededGraphLimit {}
@@ -248,8 +249,11 @@ pub fn mark_syntax<'a>(
 
 #[cfg(test)]
 mod tests {
-    use super::*;
+    use itertools::Itertools;
+    use line_numbers::SingleLineSpan;
+    use typed_arena::Arena;
 
+    use super::*;
     use crate::{
         diff::changes::ChangeKind,
         diff::graph::Edge::*,
@@ -257,10 +261,6 @@ mod tests {
         syntax::{init_all_info, AtomKind},
     };
 
-    use itertools::Itertools;
-    use line_numbers::SingleLineSpan;
-    use typed_arena::Arena;
-
     fn pos_helper(line: u32) -> Vec<SingleLineSpan> {
         vec![SingleLineSpan {
             line: line.into(),

src/diff/graph.rs

@@ -1,15 +1,17 @@
 //! A graph representation for computing tree diffs.
 
-use bumpalo::Bump;
-use hashbrown::hash_map::RawEntryMut;
 use std::{
     cell::{Cell, RefCell},
     cmp::min,
     fmt,
     hash::{Hash, Hasher},
 };
+
+use bumpalo::Bump;
+use hashbrown::hash_map::RawEntryMut;
 use strsim::normalized_levenshtein;
 
+use self::Edge::*;
 use crate::{
     diff::{
         changes::{insert_deep_unchanged, ChangeKind, ChangeMap},
@@ -18,7 +20,6 @@ use crate::{
     hash::DftHashMap,
     parse::syntax::{AtomKind, Syntax, SyntaxId},
 };
-use Edge::*;
 
 /// A vertex in a directed acyclic graph that represents a diff.
 ///

src/diff/myers_diff.rs

@@ -1,8 +1,9 @@
 //! A fast diff for linear content, using Myer's diff algorithm.
 
-use rustc_hash::FxHashSet;
 use std::hash::Hash;
 
+use rustc_hash::FxHashSet;
+
 use crate::hash::DftHashMap;
 
 #[derive(Debug, PartialEq)]

src/diff/sliders.rs

@@ -34,9 +34,8 @@ use line_numbers::SingleLineSpan;
 use crate::{
     diff::changes::{insert_deep_novel, insert_deep_unchanged, ChangeKind::*, ChangeMap},
     parse::guess_language,
-    parse::syntax::Syntax,
+    parse::syntax::Syntax::{self, *},
 };
-use Syntax::*;
 
 pub fn fix_all_sliders<'a>(
     language: guess_language::Language,
@@ -672,14 +671,15 @@ impl<'a> Syntax<'a> {
 
 #[cfg(test)]
 mod tests {
+    use pretty_assertions::assert_eq;
+    use typed_arena::Arena;
+
     use super::*;
     use crate::{
         parse::guess_language,
         parse::tree_sitter_parser::{from_language, parse},
         syntax::{init_all_info, AtomKind},
     };
-    use pretty_assertions::assert_eq;
-    use typed_arena::Arena;
 
     /// Test that we slide at the start if the unchanged node is
     /// closer than the trailing novel node.

src/diff/unchanged.rs

@@ -6,7 +6,6 @@ use std::hash::Hash;
 
 use crate::diff::changes::{insert_deep_unchanged, ChangeKind, ChangeMap};
 use crate::diff::myers_diff;
-
 use crate::parse::syntax::Syntax;
 
 const TINY_TREE_THRESHOLD: u32 = 10;
@@ -461,13 +460,14 @@ fn shrink_unchanged_at_ends<'a>(
 
 #[cfg(test)]
 mod tests {
+    use typed_arena::Arena;
+
     use super::*;
     use crate::{
         parse::guess_language,
         parse::tree_sitter_parser::{from_language, parse},
         syntax::init_all_info,
     };
-    use typed_arena::Arena;
 
     #[test]
     fn test_shrink_unchanged_at_start() {

src/display/context.rs

@@ -729,12 +729,12 @@ fn compact_gaps(
 mod tests {
     use std::iter::FromIterator;
 
-    use crate::syntax::TokenKind;
-
-    use super::*;
     use line_numbers::SingleLineSpan;
     use pretty_assertions::assert_eq;
 
+    use super::*;
+    use crate::syntax::TokenKind;
+
     #[test]
     fn test_calculate_before_context() {
         let num_context_lines = 3;

src/display/hunks.rs

@@ -5,9 +5,10 @@
 /// If we exceed this, the lines are stored in separate hunks.
 const MAX_DISTANCE: u32 = 4;
 
-use line_numbers::LineNumber;
 use std::collections::HashSet;
 
+use line_numbers::LineNumber;
+
 use crate::{
     constants::Side,
     display::context::{add_context, opposite_positions},
@@ -678,15 +679,16 @@ pub fn matched_lines_indexes_for_hunk(
 
 #[cfg(test)]
 mod tests {
-    use line_numbers::SingleLineSpan;
     use std::iter::FromIterator;
 
+    use line_numbers::SingleLineSpan;
+    use pretty_assertions::assert_eq;
+
     use super::*;
     use crate::{
         hash::DftHashMap,
         syntax::{MatchKind, TokenKind},
     };
-    use pretty_assertions::assert_eq;
 
     #[test]
     fn test_sorted_novel_positions_simple() {

src/display/json.rs

@@ -1,3 +1,8 @@
+use std::collections::HashMap;
+
+use line_numbers::LineNumber;
+use serde::{ser::SerializeStruct, Serialize, Serializer};
+
 use crate::{
     display::{
         context::{all_matched_lines_filled, opposite_positions},
@@ -8,9 +13,6 @@ use crate::{
     parse::syntax::{self, MatchedPos},
     summary::{DiffResult, FileContent, FileFormat},
 };
-use line_numbers::LineNumber;
-use serde::{ser::SerializeStruct, Serialize, Serializer};
-use std::collections::HashMap;
 
 #[derive(Debug, Serialize)]
 #[serde(rename_all = "lowercase")]

src/display/side_by_side.rs

@@ -1,14 +1,14 @@
 //! Side-by-side (two column) display of diffs.
 
-use line_numbers::LineNumber;
-use line_numbers::SingleLineSpan;
-use owo_colors::{OwoColorize, Style};
-
 use std::{
     cmp::{max, min},
     collections::HashSet,
 };
 
+use line_numbers::LineNumber;
+use line_numbers::SingleLineSpan;
+use owo_colors::{OwoColorize, Style};
+
 use crate::{
     constants::Side,
     display::context::all_matched_lines_filled,
@@ -595,14 +595,14 @@ pub fn print(
 
 #[cfg(test)]
 mod tests {
+    use pretty_assertions::assert_eq;
+
+    use super::*;
     use crate::{
         parse::guess_language::Language,
         syntax::{AtomKind, MatchKind, TokenKind},
     };
 
-    use super::*;
-    use pretty_assertions::assert_eq;
-
     #[test]
     fn test_width_calculations() {
         let line_nums = [(Some(1.into()), Some(10.into()))];

src/display/style.rs

@@ -1,5 +1,12 @@
 //! Apply colours and styling to strings.
 
+use std::cmp::{max, min};
+
+use line_numbers::LineNumber;
+use line_numbers::SingleLineSpan;
+use owo_colors::{OwoColorize, Style};
+use unicode_width::{UnicodeWidthChar, UnicodeWidthStr};
+
 use crate::{
     constants::Side,
     hash::DftHashMap,
@@ -9,12 +16,6 @@ use crate::{
     summary::FileFormat,
 };
 
-use line_numbers::LineNumber;
-use line_numbers::SingleLineSpan;
-use owo_colors::{OwoColorize, Style};
-use std::cmp::{max, min};
-use unicode_width::{UnicodeWidthChar, UnicodeWidthStr};
-
 #[derive(Clone, Copy, Debug)]
 pub enum BackgroundColor {
     Dark,
@@ -496,9 +497,10 @@ pub fn header(
 mod tests {
     const TAB_WIDTH: usize = 2;
 
-    use super::*;
     use pretty_assertions::assert_eq;
 
+    use super::*;
+
     #[test]
     fn split_string_simple() {
         assert_eq!(

src/line_parser.rs

@@ -194,10 +194,11 @@ pub fn change_positions(lhs_src: &str, rhs_src: &str) -> Vec<MatchedPos> {
 
 #[cfg(test)]
 mod tests {
-    use super::*;
     use line_numbers::SingleLineSpan;
     use pretty_assertions::assert_eq;
 
+    use super::*;
+
     #[test]
     fn test_split_newlines() {
         let s = "foo\nbar\nbaz";

src/lines.rs

@@ -1,8 +1,9 @@
 //! Manipulate lines of text and groups of lines.
 
-use line_numbers::LineNumber;
 use std::ops::Sub;
 
+use line_numbers::LineNumber;
+
 pub fn format_line_num(line_num: LineNumber) -> String {
     format!("{} ", line_num.display())
 }
@@ -51,9 +52,10 @@ pub fn is_all_whitespace(s: &str) -> bool {
 
 #[cfg(test)]
 mod tests {
-    use super::*;
     use pretty_assertions::assert_eq;
 
+    use super::*;
+
     #[test]
     fn str_max_line() {
         let line: String = "foo\nbar".into();

src/main.rs

@@ -40,6 +40,9 @@ mod version;
 #[macro_use]
 extern crate log;
 
+use log::info;
+use mimalloc::MiMalloc;
+
 use crate::conflicts::apply_conflict_markers;
 use crate::conflicts::START_LHS_MARKER;
 use crate::diff::changes::ChangeMap;
@@ -56,8 +59,6 @@ use crate::files::{
 use crate::parse::guess_language::language_globs;
 use crate::parse::guess_language::{guess, language_name, Language, LanguageOverride};
 use crate::parse::syntax;
-use log::info;
-use mimalloc::MiMalloc;
 
 /// The global allocator used by difftastic.
 ///
@@ -66,19 +67,20 @@ use mimalloc::MiMalloc;
 #[global_allocator]
 static GLOBAL: MiMalloc = MiMalloc;
 
-use crate::diff::sliders::fix_all_sliders;
-use crate::options::{DiffOptions, DisplayMode, DisplayOptions, FileArgument, Mode};
-use crate::summary::{DiffResult, FileContent, FileFormat};
-use crate::syntax::init_next_prev;
-use humansize::{format_size, BINARY};
-use owo_colors::OwoColorize;
-use rayon::prelude::*;
 use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::Arc;
 use std::{env, path::Path};
+
+use humansize::{format_size, BINARY};
+use owo_colors::OwoColorize;
+use rayon::prelude::*;
 use strum::IntoEnumIterator;
 use typed_arena::Arena;
 
+use crate::diff::sliders::fix_all_sliders;
+use crate::options::{DiffOptions, DisplayMode, DisplayOptions, FileArgument, Mode};
+use crate::summary::{DiffResult, FileContent, FileFormat};
+use crate::syntax::init_next_prev;
 use crate::{
     dijkstra::mark_syntax, lines::MaxLine, parse::syntax::init_all_info,
     parse::tree_sitter_parser as tsp,

src/parse/guess_language.rs

@@ -8,9 +8,10 @@
 //! Difftastic does not reuse languages.yml directly. Linguist has a
 //! larger set of language detection strategies.
 
+use std::{borrow::Borrow, path::Path};
+
 use lazy_static::lazy_static;
 use regex::Regex;
-use std::{borrow::Borrow, path::Path};
 use strum::{EnumIter, IntoEnumIterator};
 
 /// Languages supported by difftastic. Each language here has a
@@ -549,9 +550,10 @@ fn from_glob(path: &Path) -> Option<Language> {
 
 #[cfg(test)]
 mod tests {
-    use super::*;
     use pretty_assertions::assert_eq;
 
+    use super::*;
+
     #[test]
     fn test_guess_by_extension() {
         let path = Path::new("foo.el");

src/parse/syntax.rs

@@ -2,11 +2,13 @@
 
 #![allow(clippy::mutable_key_type)] // Hash for Syntax doesn't use mutable fields.
 
+use std::{cell::Cell, env, fmt, hash::Hash, num::NonZeroU32};
+
 use line_numbers::LinePositions;
 use line_numbers::SingleLineSpan;
-use std::{cell::Cell, env, fmt, hash::Hash, num::NonZeroU32};
 use typed_arena::Arena;
 
+use self::Syntax::*;
 use crate::{
     diff::changes::ChangeKind,
     diff::changes::{ChangeKind::*, ChangeMap},
@@ -14,7 +16,6 @@ use crate::{
     hash::DftHashMap,
     lines::is_all_whitespace,
 };
-use Syntax::*;
 
 /// A Debug implementation that does not recurse into the
 /// corresponding node mentioned for Unchanged. Otherwise we will
@@ -1030,9 +1031,10 @@ pub fn zip_repeat_shorter<Tx: Clone, Ty: Clone>(lhs: &[Tx], rhs: &[Ty]) -> Vec<(
 
 #[cfg(test)]
 mod tests {
-    use super::*;
     use pretty_assertions::assert_eq;
 
+    use super::*;
+
     /// Consider comment atoms as distinct to other atoms even if the
     /// content matches otherwise.
     #[test]

src/parse/tree_sitter_parser.rs

@@ -2,17 +2,16 @@
 
 use std::collections::HashSet;
 
-use crate::hash::DftHashMap;
-use crate::options::DiffOptions;
-use crate::parse::guess_language as guess;
 use line_numbers::LinePositions;
 use tree_sitter as ts;
 use typed_arena::Arena;
 
-use crate::parse::syntax::{AtomKind, Syntax};
-
 use super::syntax;
 use super::syntax::MatchedPos;
+use crate::hash::DftHashMap;
+use crate::options::DiffOptions;
+use crate::parse::guess_language as guess;
+use crate::parse::syntax::{AtomKind, Syntax};
 
 /// A language may contain certain nodes that are in other languages
 /// and should be parsed as such (e.g. HTML `<script>` nodes containing

tests/cli.rs

@@ -1,6 +1,7 @@
+use std::process::Command;
+
 use assert_cmd::prelude::*;
 use predicates::prelude::*;
-use std::process::Command;
 
 #[test]
 fn no_such_files() {