Move items related to computing diffs to a separate file

3 files changed, 109 insertions, 106 deletions

diff --git a/src/tools/compiletest/src/compute_diff.rs b/src/tools/compiletest/src/compute_diff.rs
new file mode 100644
index 00000000000..9ca0c69dbd3
--- /dev/null
+++ b/src/tools/compiletest/src/compute_diff.rs
@@ -0,0 +1,106 @@
+use std::collections::VecDeque;
+
+#[derive(Debug, PartialEq)]
+pub enum DiffLine {
+    Context(String),
+    Expected(String),
+    Resulting(String),
+}
+
+#[derive(Debug, PartialEq)]
+pub struct Mismatch {
+    pub line_number: u32,
+    pub lines: Vec<DiffLine>,
+}
+
+impl Mismatch {
+    fn new(line_number: u32) -> Mismatch {
+        Mismatch { line_number, lines: Vec::new() }
+    }
+}
+
+// Produces a diff between the expected output and actual output.
+pub fn make_diff(expected: &str, actual: &str, context_size: usize) -> Vec<Mismatch> {
+    let mut line_number = 1;
+    let mut context_queue: VecDeque<&str> = VecDeque::with_capacity(context_size);
+    let mut lines_since_mismatch = context_size + 1;
+    let mut results = Vec::new();
+    let mut mismatch = Mismatch::new(0);
+
+    for result in diff::lines(expected, actual) {
+        match result {
+            diff::Result::Left(str) => {
+                if lines_since_mismatch >= context_size && lines_since_mismatch > 0 {
+                    results.push(mismatch);
+                    mismatch = Mismatch::new(line_number - context_queue.len() as u32);
+                }
+
+                while let Some(line) = context_queue.pop_front() {
+                    mismatch.lines.push(DiffLine::Context(line.to_owned()));
+                }
+
+                mismatch.lines.push(DiffLine::Expected(str.to_owned()));
+                line_number += 1;
+                lines_since_mismatch = 0;
+            }
+            diff::Result::Right(str) => {
+                if lines_since_mismatch >= context_size && lines_since_mismatch > 0 {
+                    results.push(mismatch);
+                    mismatch = Mismatch::new(line_number - context_queue.len() as u32);
+                }
+
+                while let Some(line) = context_queue.pop_front() {
+                    mismatch.lines.push(DiffLine::Context(line.to_owned()));
+                }
+
+                mismatch.lines.push(DiffLine::Resulting(str.to_owned()));
+                lines_since_mismatch = 0;
+            }
+            diff::Result::Both(str, _) => {
+                if context_queue.len() >= context_size {
+                    let _ = context_queue.pop_front();
+                }
+
+                if lines_since_mismatch < context_size {
+                    mismatch.lines.push(DiffLine::Context(str.to_owned()));
+                } else if context_size > 0 {
+                    context_queue.push_back(str);
+                }
+
+                line_number += 1;
+                lines_since_mismatch += 1;
+            }
+        }
+    }
+
+    results.push(mismatch);
+    results.remove(0);
+
+    results
+}
+
+pub(crate) fn write_diff(expected: &str, actual: &str, context_size: usize) -> String {
+    use std::fmt::Write;
+    let mut output = String::new();
+    let diff_results = make_diff(expected, actual, context_size);
+    for result in diff_results {
+        let mut line_number = result.line_number;
+        for line in result.lines {
+            match line {
+                DiffLine::Expected(e) => {
+                    writeln!(output, "-\t{}", e).unwrap();
+                    line_number += 1;
+                }
+                DiffLine::Context(c) => {
+                    writeln!(output, "{}\t{}", line_number, c).unwrap();
+                    line_number += 1;
+                }
+                DiffLine::Resulting(r) => {
+                    writeln!(output, "+\t{}", r).unwrap();
+                }
+            }
+        }
+        writeln!(output).unwrap();
+    }
+    output
+}
diff --git a/src/tools/compiletest/src/main.rs b/src/tools/compiletest/src/main.rs
index 9e655557fd2..fbf3249db94 100644
--- a/src/tools/compiletest/src/main.rs
+++ b/src/tools/compiletest/src/main.rs
@@ -28,6 +28,7 @@ use self::header::{make_test_description, EarlyProps};
 mod tests;
 
 pub mod common;
+pub mod compute_diff;
 pub mod errors;
 pub mod header;
 mod json;
diff --git a/src/tools/compiletest/src/runtest.rs b/src/tools/compiletest/src/runtest.rs
index 2a4bb9eb88b..ec6c745b7d2 100644
--- a/src/tools/compiletest/src/runtest.rs
+++ b/src/tools/compiletest/src/runtest.rs
@@ -8,6 +8,7 @@ use crate::common::{CompareMode, FailMode, PassMode};
 use crate::common::{Config, TestPaths};
 use crate::common::{Pretty, RunPassValgrind};
 use crate::common::{UI_RUN_STDERR, UI_RUN_STDOUT};
+use crate::compute_diff::write_diff;
 use crate::errors::{self, Error, ErrorKind};
 use crate::header::TestProps;
 use crate::json;
@@ -18,7 +19,7 @@ use regex::{Captures, Regex};
 use rustfix::{apply_suggestions, get_suggestions_from_json, Filter};
 
 use std::collections::hash_map::DefaultHasher;
-use std::collections::{HashMap, HashSet, VecDeque};
+use std::collections::{HashMap, HashSet};
 use std::env;
 use std::ffi::{OsStr, OsString};
 use std::fs::{self, create_dir_all, File, OpenOptions};
@@ -100,111 +101,6 @@ pub fn get_lib_name(lib: &str, dylib: bool) -> String {
     }
 }
 
-#[derive(Debug, PartialEq)]
-pub enum DiffLine {
-    Context(String),
-    Expected(String),
-    Resulting(String),
-}
-
-#[derive(Debug, PartialEq)]
-pub struct Mismatch {
-    pub line_number: u32,
-    pub lines: Vec<DiffLine>,
-}
-
-impl Mismatch {
-    fn new(line_number: u32) -> Mismatch {
-        Mismatch { line_number, lines: Vec::new() }
-    }
-}
-
-// Produces a diff between the expected output and actual output.
-pub fn make_diff(expected: &str, actual: &str, context_size: usize) -> Vec<Mismatch> {
-    let mut line_number = 1;
-    let mut context_queue: VecDeque<&str> = VecDeque::with_capacity(context_size);
-    let mut lines_since_mismatch = context_size + 1;
-    let mut results = Vec::new();
-    let mut mismatch = Mismatch::new(0);
-
-    for result in diff::lines(expected, actual) {
-        match result {
-            diff::Result::Left(str) => {
-                if lines_since_mismatch >= context_size && lines_since_mismatch > 0 {
-                    results.push(mismatch);
-                    mismatch = Mismatch::new(line_number - context_queue.len() as u32);
-                }
-
-                while let Some(line) = context_queue.pop_front() {
-                    mismatch.lines.push(DiffLine::Context(line.to_owned()));
-                }
-
-                mismatch.lines.push(DiffLine::Expected(str.to_owned()));
-                line_number += 1;
-                lines_since_mismatch = 0;
-            }
-            diff::Result::Right(str) => {
-                if lines_since_mismatch >= context_size && lines_since_mismatch > 0 {
-                    results.push(mismatch);
-                    mismatch = Mismatch::new(line_number - context_queue.len() as u32);
-                }
-
-                while let Some(line) = context_queue.pop_front() {
-                    mismatch.lines.push(DiffLine::Context(line.to_owned()));
-                }
-
-                mismatch.lines.push(DiffLine::Resulting(str.to_owned()));
-                lines_since_mismatch = 0;
-            }
-            diff::Result::Both(str, _) => {
-                if context_queue.len() >= context_size {
-                    let _ = context_queue.pop_front();
-                }
-
-                if lines_since_mismatch < context_size {
-                    mismatch.lines.push(DiffLine::Context(str.to_owned()));
-                } else if context_size > 0 {
-                    context_queue.push_back(str);
-                }
-
-                line_number += 1;
-                lines_since_mismatch += 1;
-            }
-        }
-    }
-
-    results.push(mismatch);
-    results.remove(0);
-
-    results
-}
-
-fn write_diff(expected: &str, actual: &str, context_size: usize) -> String {
-    use std::fmt::Write;
-    let mut output = String::new();
-    let diff_results = make_diff(expected, actual, context_size);
-    for result in diff_results {
-        let mut line_number = result.line_number;
-        for line in result.lines {
-            match line {
-                DiffLine::Expected(e) => {
-                    writeln!(output, "-\t{}", e).unwrap();
-                    line_number += 1;
-                }
-                DiffLine::Context(c) => {
-                    writeln!(output, "{}\t{}", line_number, c).unwrap();
-                    line_number += 1;
-                }
-                DiffLine::Resulting(r) => {
-                    writeln!(output, "+\t{}", r).unwrap();
-                }
-            }
-        }
-        writeln!(output).unwrap();
-    }
-    output
-}
-
 pub fn run(config: Config, testpaths: &TestPaths, revision: Option<&str>) {
     match &*config.target {
         "arm-linux-androideabi"