Fix unified diff headers.

The length part (only) of each range is optional when equal to one.
See http://www.gnu.org/software/diffutils/manual/html_node/Detailed-Unified.html

PiperOrigin-RevId: 765326445
Change-Id: I4aec68e82f889e3b4f01861d3b6a16a8b2785ce6

Author: Abseil Team

googletest/src/gtest.cc

@@ -1488,17 +1488,17 @@ class Hunk {
   // Print a unified diff header for one hunk.
   // The format is
   //   "@@ -<left_start>,<left_length> +<right_start>,<right_length> @@"
-  // where the left/right parts are omitted if unnecessary.
+  // where the left/right lengths are omitted if unnecessary.
   void PrintHeader(std::ostream* ss) const {
-    *ss << "@@ ";
-    if (removes_) {
-      *ss << "-" << left_start_ << "," << (removes_ + common_);
+    size_t left_length = removes_ + common_;
+    size_t right_length = adds_ + common_;
+    *ss << "@@ " << "-" << left_start_;
+    if (left_length != 1) {
+      *ss << "," << left_length;
     }
-    if (removes_ && adds_) {
-      *ss << " ";
-    }
-    if (adds_) {
-      *ss << "+" << right_start_ << "," << (adds_ + common_);
+    *ss << " " << "+" << right_start_;
+    if (right_length != 1) {
+      *ss << "," << right_length;
     }
     *ss << " @@\n";
   }

googletest/test/googletest-output-test-golden-lin.txt

@@ -62,7 +62,7 @@ Expected equality of these values:
     Which is: "\"Line\0 1\"\nLine 2"
   "Line 2"
 With diff:
-@@ -1,2 @@
+@@ -1,2 +1 @@
 -\"Line\0 1\"
  Line 2
 

googletest/test/gtest_unittest.cc

@@ -3579,13 +3579,13 @@ TEST(EditDistance, TestSuites) {
       {__LINE__, "A", "A", " ", ""},
       {__LINE__, "ABCDE", "ABCDE", "     ", ""},
       // Simple adds.
-      {__LINE__, "X", "XA", " +", "@@ +1,2 @@\n X\n+A\n"},
-      {__LINE__, "X", "XABCD", " ++++", "@@ +1,5 @@\n X\n+A\n+B\n+C\n+D\n"},
+      {__LINE__, "X", "XA", " +", "@@ -1 +1,2 @@\n X\n+A\n"},
+      {__LINE__, "X", "XABCD", " ++++", "@@ -1 +1,5 @@\n X\n+A\n+B\n+C\n+D\n"},
       // Simple removes.
-      {__LINE__, "XA", "X", " -", "@@ -1,2 @@\n X\n-A\n"},
-      {__LINE__, "XABCD", "X", " ----", "@@ -1,5 @@\n X\n-A\n-B\n-C\n-D\n"},
+      {__LINE__, "XA", "X", " -", "@@ -1,2 +1 @@\n X\n-A\n"},
+      {__LINE__, "XABCD", "X", " ----", "@@ -1,5 +1 @@\n X\n-A\n-B\n-C\n-D\n"},
       // Simple replaces.
-      {__LINE__, "A", "a", "/", "@@ -1,1 +1,1 @@\n-A\n+a\n"},
+      {__LINE__, "A", "a", "/", "@@ -1 +1 @@\n-A\n+a\n"},
       {__LINE__, "ABCD", "abcd", "////",
        "@@ -1,4 +1,4 @@\n-A\n-B\n-C\n-D\n+a\n+b\n+c\n+d\n"},
       // Path finding.