Clarify wording when a parsed file has no changes at all

CHANGELOG.md

@@ -6,6 +6,10 @@ Difftastic no longer shows "1/1" when a file only has a single hunk.
 
 Improved Scala syntax highlighting.
 
+When a file is entirely unchanged, difftastic now shows "no changes"
+even if it successfully parsed. Previously it would only show "no
+syntactic changes".
+
 ## 0.24 (release 26th March 2022)
 
 ### Diffing

sample_files/compare.expected

@@ -40,6 +40,9 @@ sample_files/helpful_before.el sample_files/helpful_after.el
 sample_files/helpful-unit-test-before.el sample_files/helpful-unit-test-after.el
 e98b3bad1d2db81284f11d3936078ece  -
 
+sample_files/identical_before.scala sample_files/identical_after.scala
+ff7c743ea9a423405682871e80149462  -
+
 sample_files/if_before.py sample_files/if_after.py
 e633761742973b2ef3b2ed078cedbdf2  -
 

sample_files/identical_after.scala

@@ -0,0 +1,5 @@
+object Hello {
+    def main(args: Array[String]) = {
+        println("Hello, world")
+    }
+}

sample_files/identical_before.scala

@@ -0,0 +1,5 @@
+object Hello {
+    def main(args: Array[String]) = {
+        println("Hello, world")
+    }
+}

src/main.rs

@@ -395,7 +395,7 @@ fn print_diff_result(
                         "{}",
                         style::header(&summary.path, 1, 1, &lang_name, use_color, background)
                     );
-                    if lang_name == "Text" {
+                    if lang_name == "Text" || summary.lhs_src == summary.rhs_src {
                         // TODO: there are other Text names now, so
                         // they will hit the second case incorrectly.
                         println!("No changes.\n");

src/summary.rs

@@ -1,6 +1,6 @@
 use crate::syntax::MatchedPos;
 
-#[derive(Debug)]
+#[derive(Debug, PartialEq, Eq)]
 pub enum FileContent {
     Text(String),
     Binary(Vec<u8>),