vim-patch:8.2.3932: C line comment not formatted properly

Problem:    C line comment not formatted properly.
Solution:   If a line comment follows after "#if" the next line is not the end
            of a paragraph.
264d3ddac0

src/nvim/edit.c

@@ -6137,8 +6137,7 @@ static void internal_format(int textwidth, int second_indent, int flags, int for
         if (curwin->w_cursor.col <= (colnr_T)wantcol) {
           break;
         }
-      } else if ((cc >= 0x100 || !utf_allow_break_before(cc))
+      } else if ((cc >= 0x100 || !utf_allow_break_before(cc)) && fo_multibyte) {
-                 && fo_multibyte) {
         int ncc;
         bool allow_break;
 

src/nvim/ops.c

@@ -4350,7 +4350,7 @@ void format_lines(linenr_T line_count, int avoid_fex)
   int leader_len = 0;               // leader len of current line
   int next_leader_len;              // leader len of next line
   char_u *leader_flags = NULL;      // flags for leader of current line
-  char_u *next_leader_flags;        // flags for leader of next line
+  char_u *next_leader_flags = NULL;  // flags for leader of next line
   bool advance = true;
   int second_indent = -1;           // indent for second line (comment aware)
   bool first_par_line = true;
@@ -4467,7 +4467,14 @@ void format_lines(linenr_T line_count, int avoid_fex)
                           leader_len, leader_flags,
                           next_leader_len,
                           next_leader_flags)) {
-        is_end_par = true;
+        // Special case: If the next line starts with a line comment
+        // and this line has a line comment after some text, the
+        // paragraph doesn't really end.
+        if (next_leader_flags == NULL
+            || STRNCMP(next_leader_flags, "://", 3) != 0
+            || check_linecomment(get_cursor_line_ptr()) == MAXCOL) {
+          is_end_par = true;
+        }
       }
 
       /*

src/nvim/testdir/test_textformat.vim

@@ -223,6 +223,21 @@ func Test_format_c_comment()
   END
   call assert_equal(expected, getline(1, '$'))
 
+  %del
+  let text =<< trim END
+      #if 0           // This is another long end of
+                      // line comment that
+                      // wraps.
+  END
+  call setline(1, text)
+  normal gq2j
+  let expected =<< trim END
+      #if 0           // This is another long
+                      // end of line comment
+                      // that wraps.
+  END
+  call assert_equal(expected, getline(1, '$'))
+
   bwipe!
 endfunc