Merge pull request #17254 from zeertzjq/vim-8.2.3787

vim-patch:8.2.{3787,3932,3934,3935,3938}: text formatting patches

8 files changed, 288 insertions, 129 deletions

diff --git a/src/nvim/change.c b/src/nvim/change.c
index 0c16b204e3..54c4ba5319 100644
--- a/src/nvim/change.c
+++ b/src/nvim/change.c
@@ -952,11 +952,13 @@ int copy_indent(int size, char_u *src)
 ///
 /// "second_line_indent": indent for after ^^D in Insert mode or if flag
 ///                       OPENLINE_COM_LIST
+/// "did_do_comment" is set to true when intentionally putting the comment
+/// leader in fromt of the new line.
 ///
 /// @param dir  FORWARD or BACKWARD
 ///
 /// @return true on success, false on failure
-int open_line(int dir, int flags, int second_line_indent)
+int open_line(int dir, int flags, int second_line_indent, bool *did_do_comment)
 {
   char_u *next_line = NULL;       // copy of the next line
   char_u *p_extra = NULL;         // what goes to next line
@@ -969,6 +971,7 @@ int open_line(int dir, int flags, int second_line_indent)
   bool retval = false;            // return value
   int extra_len = 0;              // length of p_extra string
   int lead_len;                   // length of comment leader
+  int comment_start = 0;          // start index of the comment leader
   char_u *lead_flags;             // position in 'comments' for comment leader
   char_u *leader = NULL;          // copy of comment leader
   char_u *allocated = NULL;       // allocated memory
@@ -977,6 +980,7 @@ int open_line(int dir, int flags, int second_line_indent)
   pos_T *pos;
   bool do_si = (!p_paste && curbuf->b_p_si && !curbuf->b_p_cin
                 && *curbuf->b_p_inde == NUL);
+  bool do_cindent;
   bool no_si = false;             // reset did_si afterwards
   int first_char = NUL;           // init for GCC
   int vreplace_mode;
@@ -1189,11 +1193,30 @@ int open_line(int dir, int flags, int second_line_indent)
     did_ai = true;
   }
 
+  // May do indenting after opening a new line.
+  do_cindent = !p_paste && (curbuf->b_p_cin || *curbuf->b_p_inde != NUL)
+               && in_cinkeys(dir == FORWARD ? KEY_OPEN_FORW : KEY_OPEN_BACK,
+                             ' ', linewhite(curwin->w_cursor.lnum));
+
   // Find out if the current line starts with a comment leader.
   // This may then be inserted in front of the new line.
   end_comment_pending = NUL;
-  if (flags & OPENLINE_DO_COM) {
+  if (flags & OPENLINE_DO_COM && dir == FORWARD) {
+    // Check for a line comment after code.
     lead_len = get_leader_len(saved_line, &lead_flags, dir == BACKWARD, true);
+    if (lead_len == 0 && do_cindent) {
+      comment_start = check_linecomment(saved_line);
+      if (comment_start != MAXCOL) {
+        lead_len = get_leader_len(saved_line + comment_start,
+                                  &lead_flags, false, true);
+        if (lead_len != 0) {
+          lead_len += comment_start;
+          if (did_do_comment != NULL) {
+            *did_do_comment = true;
+          }
+        }
+      }
+    }
   } else {
     lead_len = 0;
   }
@@ -1349,6 +1372,13 @@ int open_line(int dir, int flags, int second_line_indent)
 
       STRLCPY(leader, saved_line, lead_len + 1);
 
+      // TODO(vim): handle multi-byte and double width chars
+      for (int li = 0; li < comment_start; li++) {
+        if (!ascii_iswhite(leader[li])) {
+          leader[li] = ' ';
+        }
+      }
+
       // Replace leader with lead_repl, right or left adjusted
       if (lead_repl != NULL) {
         int c = 0;
@@ -1758,13 +1788,7 @@ int open_line(int dir, int flags, int second_line_indent)
     ai_col = (colnr_T)getwhitecols_curline();
   }
   // May do indenting after opening a new line.
-  if (!p_paste
-      && (curbuf->b_p_cin
-          || *curbuf->b_p_inde != NUL
-          )
-      && in_cinkeys(dir == FORWARD
-                    ? KEY_OPEN_FORW
-                    : KEY_OPEN_BACK, ' ', linewhite(curwin->w_cursor.lnum))) {
+  if (do_cindent) {
     do_c_expr_indent();
     ai_col = (colnr_T)getwhitecols_curline();
   }
diff --git a/src/nvim/edit.c b/src/nvim/edit.c
index 095fa14752..f96e7261ca 100644
--- a/src/nvim/edit.c
+++ b/src/nvim/edit.c
@@ -6021,6 +6021,7 @@ static void internal_format(int textwidth, int second_indent, int flags, int for
     char_u *saved_text = NULL;
     colnr_T col;
     colnr_T end_col;
+    bool did_do_comment = false;
 
     virtcol = get_nolist_virtcol()
               + char2cells(c != NUL ? c : gchar_cursor());
@@ -6136,8 +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))
-                 && fo_multibyte) {
+      } else if ((cc >= 0x100 || !utf_allow_break_before(cc)) && fo_multibyte) {
         int ncc;
         bool allow_break;
 
@@ -6294,11 +6294,18 @@ static void internal_format(int textwidth, int second_indent, int flags, int for
               + (fo_white_par ? OPENLINE_KEEPTRAIL : 0)
               + (do_comments ? OPENLINE_DO_COM : 0)
               + ((flags & INSCHAR_COM_LIST) ? OPENLINE_COM_LIST : 0),
-              ((flags & INSCHAR_COM_LIST) ? second_indent : old_indent));
+              ((flags & INSCHAR_COM_LIST) ? second_indent : old_indent),
+              &did_do_comment);
     if (!(flags & INSCHAR_COM_LIST)) {
       old_indent = 0;
     }
 
+    // If a comment leader was inserted, may also do this on a following
+    // line.
+    if (did_do_comment) {
+      no_leader = false;
+    }
+
     replace_offset = 0;
     if (first_line) {
       if (!(flags & INSCHAR_COM_LIST)) {
@@ -8292,6 +8299,7 @@ static bool ins_bs(int c, int mode, int *inserted_space_p)
   int in_indent;
   int oldState;
   int cpc[MAX_MCO];                 // composing characters
+  bool call_fix_indent = false;
 
   // can't delete anything in an empty file
   // can't backup past first character in buffer
@@ -8435,6 +8443,8 @@ static bool ins_bs(int c, int mode, int *inserted_space_p)
       beginline(BL_WHITE);
       if (curwin->w_cursor.col < save_col) {
         mincol = curwin->w_cursor.col;
+        // should now fix the indent to match with the previous line
+        call_fix_indent = true;
       }
       curwin->w_cursor.col = save_col;
     }
@@ -8569,6 +8579,11 @@ static bool ins_bs(int c, int mode, int *inserted_space_p)
   if (curwin->w_cursor.col <= 1) {
     did_ai = false;
   }
+
+  if (call_fix_indent) {
+    fix_indent();
+  }
+
   // It's a little strange to put backspaces into the redo
   // buffer, but it makes auto-indent a lot easier to deal
   // with.
@@ -9183,7 +9198,7 @@ static bool ins_eol(int c)
   AppendToRedobuff(NL_STR);
   bool i = open_line(FORWARD,
                      has_format_option(FO_RET_COMS) ? OPENLINE_DO_COM : 0,
-                     old_indent);
+                     old_indent, NULL);
   old_indent = 0;
   can_cindent = true;
   // When inserting a line the cursor line must never be in a closed fold.
diff --git a/src/nvim/indent_c.c b/src/nvim/indent_c.c
index eb24e13d24..7f483d02ab 100644
--- a/src/nvim/indent_c.c
+++ b/src/nvim/indent_c.c
@@ -41,9 +41,7 @@ static pos_T *ind_find_start_comment(void)  // XXX
 
 pos_T *find_start_comment(int ind_maxcomment)  // XXX
 {
-  pos_T       *pos;
-  char_u      *line;
-  char_u      *p;
+  pos_T *pos;
   int64_t cur_maxcomment = ind_maxcomment;
 
   for (;; ) {
@@ -55,11 +53,9 @@ pos_T *find_start_comment(int ind_maxcomment)  // XXX
      * Check if the comment start we found is inside a string.
      * If it is then restrict the search to below this line and try again.
      */
-    line = ml_get(pos->lnum);
-    for (p = line; *p && (colnr_T)(p - line) < pos->col; ++p)
-      p = skip_string(p);
-    if ((colnr_T)(p - line) <= pos->col)
+    if (!is_pos_in_string(ml_get(pos->lnum), pos->col)) {
       break;
+    }
     cur_maxcomment = curwin->w_cursor.lnum - pos->lnum - 1;
     if (cur_maxcomment <= 0) {
       pos = NULL;
@@ -110,8 +106,6 @@ static pos_T *ind_find_start_CORS(linenr_T *is_raw)
 static pos_T *find_start_rawstring(int ind_maxcomment)  // XXX
 {
     pos_T *pos;
-    char_u *line;
-    char_u *p;
     long cur_maxcomment = ind_maxcomment;
 
     for (;;)
@@ -124,11 +118,9 @@ static pos_T *find_start_rawstring(int ind_maxcomment)  // XXX
          * Check if the raw string start we found is inside a string.
          * If it is then restrict the search to below this line and try again.
          */
-        line = ml_get(pos->lnum);
-        for (p = line; *p && (colnr_T)(p - line) < pos->col; ++p)
-            p = skip_string(p);
-        if ((colnr_T)(p - line) <= pos->col)
-            break;
+        if (!is_pos_in_string(ml_get(pos->lnum), pos->col)) {
+          break;
+        }
         cur_maxcomment = curwin->w_cursor.lnum - pos->lnum - 1;
         if (cur_maxcomment <= 0)
         {
@@ -143,7 +135,7 @@ static pos_T *find_start_rawstring(int ind_maxcomment)  // XXX
  * Skip to the end of a "string" and a 'c' character.
  * If there is no string or character, return argument unmodified.
  */
-static char_u *skip_string(char_u *p)
+static const char_u *skip_string(const char_u *p)
 {
   int i;
 
@@ -178,24 +170,24 @@ static char_u *skip_string(char_u *p)
         continue;  // continue for another string
       }
     } else if (p[0] == 'R' && p[1] == '"') {
-        // Raw string: R"[delim](...)[delim]"
-        char_u *delim = p + 2;
-        char_u *paren = vim_strchr(delim, '(');
-
-        if (paren != NULL) {
-            const ptrdiff_t delim_len = paren - delim;
-
-            for (p += 3; *p; ++p)
-                if (p[0] == ')' && STRNCMP(p + 1, delim, delim_len) == 0
-                        && p[delim_len + 1] == '"')
-                {
-                    p += delim_len + 1;
-                    break;
-                }
-            if (p[0] == '"') {
-              continue;  // continue for another string
-            }
+      // Raw string: R"[delim](...)[delim]"
+      const char_u *delim = p + 2;
+      const char_u *paren = vim_strchr(delim, '(');
+
+      if (paren != NULL) {
+        const ptrdiff_t delim_len = paren - delim;
+
+        for (p += 3; *p; p++) {
+          if (p[0] == ')' && STRNCMP(p + 1, delim, delim_len) == 0
+              && p[delim_len + 1] == '"') {
+            p += delim_len + 1;
+            break;
+          }
+        }
+        if (p[0] == '"') {
+          continue;  // continue for another string
         }
+      }
     }
     break;                                  // no string found
   }
@@ -205,6 +197,16 @@ static char_u *skip_string(char_u *p)
   return p;
 }
 
+/// @returns true if "line[col]" is inside a C string.
+int is_pos_in_string(const char_u *line, colnr_T col)
+{
+  const char_u *p;
+
+  for (p = line; *p && (colnr_T)(p - line) < col; p++) {
+    p = skip_string(p);
+  }
+  return !((colnr_T)(p - line) <= col);
+}
 
 /*
  * Functions for C-indenting.
@@ -218,7 +220,7 @@ static char_u *skip_string(char_u *p)
 /*
  * Return true if the string "line" starts with a word from 'cinwords'.
  */
-bool cin_is_cinword(char_u *line)
+bool cin_is_cinword(const char_u *line)
 {
   bool retval = false;
 
@@ -246,10 +248,10 @@ bool cin_is_cinword(char_u *line)
  * Skip over white space and C comments within the line.
  * Also skip over Perl/shell comments if desired.
  */
-static char_u *cin_skipcomment(char_u *s)
+static const char_u *cin_skipcomment(const char_u *s)
 {
   while (*s) {
-    char_u *prev_s = s;
+    const char_u *prev_s = s;
 
     s = skipwhite(s);
 
@@ -283,7 +285,7 @@ static char_u *cin_skipcomment(char_u *s)
  * Return TRUE if there is no code at *s.  White space and comments are
  * not considered code.
  */
-static int cin_nocode(char_u *s)
+static int cin_nocode(const char_u *s)
 {
   return *cin_skipcomment(s) == NUL;
 }
@@ -312,9 +314,9 @@ static pos_T *find_line_comment(void)  // XXX
 }
 
 /// Checks if `text` starts with "key:".
-static bool cin_has_js_key(char_u *text)
+static bool cin_has_js_key(const char_u *text)
 {
-  char_u *s = skipwhite(text);
+  const char_u *s = skipwhite(text);
 
   char_u quote = 0;
   if (*s == '\'' || *s == '"') {
@@ -341,7 +343,7 @@ static bool cin_has_js_key(char_u *text)
 
 /// Checks if string matches "label:"; move to character after ':' if true.
 /// "*s" must point to the start of the label, if there is one.
-static bool cin_islabel_skip(char_u **s)
+static bool cin_islabel_skip(const char_u **s)
   FUNC_ATTR_NONNULL_ALL
 {
   if (!vim_isIDc(**s)) {            // need at least one ID character
@@ -361,7 +363,7 @@ static bool cin_islabel_skip(char_u **s)
 // Note: curwin->w_cursor must be where we are looking for the label.
 bool cin_islabel(void)  // XXX
 {
-  char_u *s = cin_skipcomment(get_cursor_line_ptr());
+  const char_u *s = cin_skipcomment(get_cursor_line_ptr());
 
   // Exclude "default" from labels, since it should be indented
   // like a switch label.  Same for C++ scope declarations.
@@ -380,8 +382,8 @@ bool cin_islabel(void)  // XXX
    * label.
    */
   pos_T cursor_save;
-  pos_T   *trypos;
-  char_u  *line;
+  pos_T *trypos;
+  const char_u *line;
 
   cursor_save = curwin->w_cursor;
   while (curwin->w_cursor.lnum > 1) {
@@ -424,8 +426,8 @@ bool cin_islabel(void)  // XXX
  */
 static int cin_isinit(void)
 {
-  char_u      *s;
-  static char *skip[] = {"static", "public", "protected", "private"};
+  const char_u *s;
+  static char *skip[] = { "static", "public", "protected", "private" };
 
   s = cin_skipcomment(get_cursor_line_ptr());
 
@@ -460,7 +462,7 @@ static int cin_isinit(void)
  * Recognize a switch label: "case .*:" or "default:".
  */
 bool cin_iscase(
-    char_u *s,
+    const char_u *s,
     bool strict     // Allow relaxed check of case statement for JS
 )
 {
@@ -503,7 +505,7 @@ bool cin_iscase(
 /*
  * Recognize a "default" switch label.
  */
-static int cin_isdefault(char_u *s)
+static int cin_isdefault(const char_u *s)
 {
   return STRNCMP(s, "default", 7) == 0
          && *(s = cin_skipcomment(s + 7)) == ':'
@@ -513,7 +515,7 @@ static int cin_isdefault(char_u *s)
 /*
  * Recognize a "public/private/protected" scope declaration label.
  */
-bool cin_isscopedecl(char_u *s)
+bool cin_isscopedecl(const char_u *s)
 {
   int i;
 
@@ -534,9 +536,9 @@ bool cin_isscopedecl(char_u *s)
 #define FIND_NAMESPACE_LIM 20
 
 // Recognize a "namespace" scope declaration.
-static bool cin_is_cpp_namespace(char_u *s)
+static bool cin_is_cpp_namespace(const char_u *s)
 {
-  char_u *p;
+  const char_u *p;
   bool has_name = false;
   bool has_name_start = false;
 
@@ -581,7 +583,7 @@ static bool cin_is_cpp_namespace(char_u *s)
  *	  case 234:    a = b;
  *		       ^
  */
-static char_u *after_label(char_u *l)
+static const char_u *after_label(const char_u *l)
 {
   for (; *l; ++l) {
     if (*l == ':') {
@@ -608,10 +610,10 @@ static char_u *after_label(char_u *l)
  */
 static int get_indent_nolabel(linenr_T lnum)  // XXX
 {
-  char_u      *l;
+  const char_u *l;
   pos_T fp;
   colnr_T col;
-  char_u      *p;
+  const char_u *p;
 
   l = ml_get(lnum);
   p = after_label(l);
@@ -630,9 +632,9 @@ static int get_indent_nolabel(linenr_T lnum)  // XXX
  *   label:	if (asdf && asdfasdf)
  *		^
  */
-static int skip_label(linenr_T lnum, char_u **pp)
+static int skip_label(linenr_T lnum, const char_u **pp)
 {
-  char_u      *l;
+  const char_u *l;
   int amount;
   pos_T cursor_save;
 
@@ -713,8 +715,8 @@ static int cin_first_id_amount(void)
  */
 static int cin_get_equal_amount(linenr_T lnum)
 {
-  char_u      *line;
-  char_u      *s;
+  const char_u *line;
+  const char_u *s;
   colnr_T col;
   pos_T fp;
 
@@ -752,7 +754,7 @@ static int cin_get_equal_amount(linenr_T lnum)
 /*
  * Recognize a preprocessor statement: Any line that starts with '#'.
  */
-static int cin_ispreproc(char_u *s)
+static int cin_ispreproc(const char_u *s)
 {
   if (*skipwhite(s) == '#')
     return TRUE;
@@ -763,9 +765,9 @@ static int cin_ispreproc(char_u *s)
 /// continuation line of a preprocessor statement.  Decrease "*lnump" to the
 /// start and return the line in "*pp".
 /// Put the amount of indent in "*amount".
-static int cin_ispreproc_cont(char_u **pp, linenr_T *lnump, int *amount)
+static int cin_ispreproc_cont(const char_u **pp, linenr_T *lnump, int *amount)
 {
-  char_u      *line = *pp;
+  const char_u *line = *pp;
   linenr_T lnum = *lnump;
   int retval = false;
   int candidate_amount = *amount;
@@ -799,7 +801,7 @@ static int cin_ispreproc_cont(char_u **pp, linenr_T *lnump, int *amount)
 /*
  * Recognize the start of a C or C++ comment.
  */
-static int cin_iscomment(char_u *p)
+static int cin_iscomment(const char_u *p)
 {
   return p[0] == '/' && (p[1] == '*' || p[1] == '/');
 }
@@ -807,7 +809,7 @@ static int cin_iscomment(char_u *p)
 /*
  * Recognize the start of a "//" comment.
  */
-static int cin_islinecomment(char_u *p)
+static int cin_islinecomment(const char_u *p)
 {
   return p[0] == '/' && p[1] == '/';
 }
@@ -822,8 +824,8 @@ static int cin_islinecomment(char_u *p)
  * both apply in order to determine initializations).
  */
 static char_u
-cin_isterminated (
-    char_u *s,
+cin_isterminated(
+    const char_u *s,
     int incl_open,                  // include '{' at the end as terminator
     int incl_comma                 // recognize a trailing comma
 )
@@ -872,9 +874,9 @@ cin_isterminated (
 ///                 lines here.
 /// @param[in]  first_lnum Where to start looking.
 /// @param[in]  min_lnum The line before which we will not be looking.
-static int cin_isfuncdecl(char_u **sp, linenr_T first_lnum, linenr_T min_lnum)
+static int cin_isfuncdecl(const char_u **sp, linenr_T first_lnum, linenr_T min_lnum)
 {
-  char_u      *s;
+  const char_u *s;
   linenr_T lnum = first_lnum;
   linenr_T save_lnum = curwin->w_cursor.lnum;
   int retval = false;
@@ -975,12 +977,12 @@ done:
   return retval;
 }
 
-static int cin_isif(char_u *p)
+static int cin_isif(const char_u *p)
 {
   return STRNCMP(p, "if", 2) == 0 && !vim_isIDc(p[2]);
 }
 
-static int cin_iselse(char_u *p)
+static int cin_iselse(const char_u *p)
 {
   if (*p == '}') {          // accept "} else"
     p = cin_skipcomment(p + 1);
@@ -988,7 +990,7 @@ static int cin_iselse(char_u *p)
   return STRNCMP(p, "else", 4) == 0 && !vim_isIDc(p[4]);
 }
 
-static int cin_isdo(char_u *p)
+static int cin_isdo(const char_u *p)
 {
   return STRNCMP(p, "do", 2) == 0 && !vim_isIDc(p[2]);
 }
@@ -998,7 +1000,7 @@ static int cin_isdo(char_u *p)
  * We only accept a "while (condition) ;", with only white space between the
  * ')' and ';'. The condition may be spread over several lines.
  */
-static int cin_iswhileofdo(char_u *p, linenr_T lnum)  // XXX
+static int cin_iswhileofdo(const char_u *p, linenr_T lnum)  // XXX
 {
   pos_T cursor_save;
   pos_T       *trypos;
@@ -1032,7 +1034,7 @@ static int cin_iswhileofdo(char_u *p, linenr_T lnum)  // XXX
  * Otherwise return !0 and update "*poffset" to point to the place where the
  * string was found.
  */
-static int cin_is_if_for_while_before_offset(char_u *line, int *poffset)
+static int cin_is_if_for_while_before_offset(const char_u *line, int *poffset)
 {
   int offset = *poffset;
 
@@ -1076,10 +1078,10 @@ probablyFound:
  */
 static int cin_iswhileofdo_end(int terminated)
 {
-  char_u      *line;
-  char_u      *p;
-  char_u      *s;
-  pos_T       *trypos;
+  const char_u *line;
+  const char_u *p;
+  const char_u *s;
+  pos_T *trypos;
   int i;
 
   if (terminated != ';') {      // there must be a ';' at the end
@@ -1119,7 +1121,7 @@ static int cin_iswhileofdo_end(int terminated)
   return FALSE;
 }
 
-static int cin_isbreak(char_u *p)
+static int cin_isbreak(const char_u *p)
 {
   return STRNCMP(p, "break", 5) == 0 && !vim_isIDc(p[5]);
 }
@@ -1139,10 +1141,10 @@ static int cin_isbreak(char_u *p)
  */
 static int cin_is_cpp_baseclass(cpp_baseclass_cache_T *cached) {
   lpos_T *pos = &cached->lpos;  // find position
-  char_u      *s;
+  const char_u *s;
   int class_or_struct, lookfor_ctor_init, cpp_base_class;
   linenr_T lnum = curwin->w_cursor.lnum;
-  char_u      *line = get_cursor_line_ptr();
+  const char_u *line = get_cursor_line_ptr();
 
   if (pos->lnum <= lnum) {
     return cached->found;  // Use the cached result
@@ -1310,10 +1312,10 @@ static int get_baseclass_amount(int col)
  * white space and comments.  Skip strings and comments.
  * Ignore "ignore" after "find" if it's not NULL.
  */
-static int cin_ends_in(char_u *s, char_u *find, char_u *ignore)
+static int cin_ends_in(const char_u *s, const char_u *find, const char_u *ignore)
 {
-  char_u      *p = s;
-  char_u      *r;
+  const char_u *p = s;
+  const char_u *r;
   int len = (int)STRLEN(find);
 
   while (*p != NUL) {
@@ -1334,7 +1336,7 @@ static int cin_ends_in(char_u *s, char_u *find, char_u *ignore)
 /*
  * Return TRUE when "s" starts with "word" and then a non-ID character.
  */
-static int cin_starts_with(char_u *s, char *word)
+static int cin_starts_with(const char_u *s, const char *word)
 {
   int l = (int)STRLEN(word);
 
@@ -1342,10 +1344,10 @@ static int cin_starts_with(char_u *s, char *word)
 }
 
 /// Recognize a `extern "C"` or `extern "C++"` linkage specifications.
-static int cin_is_cpp_extern_c(char_u *s)
+static int cin_is_cpp_extern_c(const char_u *s)
 {
-  char_u  *p;
-  int     has_string_literal = false;
+  const char_u *p;
+  int has_string_literal = false;
 
   s = cin_skipcomment(s);
   if (STRNCMP(s, "extern", 6) == 0 && (s[6] == NUL || !vim_iswordc(s[6]))) {
@@ -1384,9 +1386,9 @@ static int cin_is_cpp_extern_c(char_u *s)
  */
 static int cin_skip2pos(pos_T *trypos)
 {
-  char_u      *line;
-  char_u      *p;
-  char_u      *new_p;
+  const char_u *line;
+  const char_u *p;
+  const char_u *new_p;
 
   p = line = ml_get(trypos->lnum);
   while (*p && (colnr_T)(p - line) < trypos->col) {
@@ -1529,7 +1531,7 @@ static int corr_ind_maxparen(pos_T *startpos)
  * Set w_cursor.col to the column number of the last unmatched ')' or '{' in
  * line "l".  "l" must point to the start of the line.
  */
-static int find_last_paren(char_u *l, int start, int end)
+static int find_last_paren(const char_u *l, int start, int end)
 {
   int i;
   int retval = FALSE;
@@ -1801,8 +1803,8 @@ int get_c_indent(void)
 #define BRACE_AT_START          2           // '{' is at start of line
 #define BRACE_AT_END            3           // '{' is at end of line
   linenr_T ourscope;
-  char_u      *l;
-  char_u      *look;
+  const char_u *l;
+  const char_u *look;
   char_u terminated;
   int lookfor;
 #define LOOKFOR_INITIAL         0
@@ -1906,12 +1908,25 @@ int get_c_indent(void)
    * If we're inside a "//" comment and there is a "//" comment in a
    * previous line, lineup with that one.
    */
-  if (cin_islinecomment(theline)
-      && (trypos = find_line_comment()) != NULL) {  // XXX
-    // find how indented the line beginning the comment is
-    getvcol(curwin, trypos, &col, NULL, NULL);
-    amount = col;
-    goto theend;
+  if (cin_islinecomment(theline)) {
+    pos_T linecomment_pos;
+
+    trypos = find_line_comment();  // XXX
+    if (trypos == NULL && curwin->w_cursor.lnum > 1) {
+      // There may be a statement before the comment, search from the end
+      // of the line for a comment start.
+      linecomment_pos.col = check_linecomment(ml_get(curwin->w_cursor.lnum - 1));
+      if (linecomment_pos.col != MAXCOL) {
+        trypos = &linecomment_pos;
+        trypos->lnum = curwin->w_cursor.lnum - 1;
+      }
+    }
+    if (trypos != NULL) {
+      // find how indented the line beginning the comment is
+      getvcol(curwin, trypos, &col, NULL, NULL);
+      amount = col;
+      goto theend;
+    }
   }
   /*
    * If we're inside a comment and not looking at the start of the
@@ -3602,9 +3617,9 @@ laterend:
 
 static int find_match(int lookfor, linenr_T ourscope)
 {
-  char_u      *look;
-  pos_T       *theirscope;
-  char_u      *mightbeif;
+  const char_u *look;
+  pos_T *theirscope;
+  const char_u *mightbeif;
   int elselevel;
   int whilelevel;
 
diff --git a/src/nvim/normal.c b/src/nvim/normal.c
index 28e5d47dbc..6e36226914 100644
--- a/src/nvim/normal.c
+++ b/src/nvim/normal.c
@@ -6685,9 +6685,8 @@ static void n_opencmd(cmdarg_T *cap)
                           (cap->cmdchar == 'o' ? 1 : 0))
                )
         && open_line(cap->cmdchar == 'O' ? BACKWARD : FORWARD,
-                     has_format_option(FO_OPEN_COMS)
-                     ? OPENLINE_DO_COM : 0,
-                     0)) {
+                     has_format_option(FO_OPEN_COMS) ? OPENLINE_DO_COM : 0,
+                     0, NULL)) {
       if (win_cursorline_standout(curwin)) {
         // force redraw of cursorline
         curwin->w_valid &= ~VALID_CROW;
diff --git a/src/nvim/ops.c b/src/nvim/ops.c
index 83a7c31991..11484eee57 100644
--- a/src/nvim/ops.c
+++ b/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;
+        }
       }
 
       /*
diff --git a/src/nvim/search.c b/src/nvim/search.c
index 906c9a6f47..93180f97fe 100644
--- a/src/nvim/search.c
+++ b/src/nvim/search.c
@@ -26,6 +26,7 @@
 #include "nvim/func_attr.h"
 #include "nvim/getchar.h"
 #include "nvim/indent.h"
+#include "nvim/indent_c.h"
 #include "nvim/main.h"
 #include "nvim/mark.h"
 #include "nvim/mbyte.h"
@@ -2313,12 +2314,9 @@ pos_T *findmatchlimit(oparg_T *oap, int initc, int flags, int64_t maxtravel)
   return (pos_T *)NULL;         // never found it
 }
 
-/*
- * Check if line[] contains a / / comment.
- * Return MAXCOL if not, otherwise return the column.
- * TODO: skip strings.
- */
-static int check_linecomment(const char_u *line)
+/// Check if line[] contains a / / comment.
+/// @returns MAXCOL if not, otherwise return the column.
+int check_linecomment(const char_u *line)
 {
   const char_u *p = line;  // scan from start
   // skip Lispish one-line comments
@@ -2338,7 +2336,8 @@ static int check_linecomment(const char_u *line)
             in_str = true;
           }
         } else if (!in_str && ((p - line) < 2
-                               || (*(p - 1) != '\\' && *(p - 2) != '#'))) {
+                               || (*(p - 1) != '\\' && *(p - 2) != '#'))
+                   && !is_pos_in_string(line, (colnr_T)(p - line))) {
           break;                // found!
         }
         p++;
@@ -2348,9 +2347,11 @@ static int check_linecomment(const char_u *line)
     }
   } else {
     while ((p = vim_strchr(p, '/')) != NULL) {
-      // accept a double /, unless it's preceded with * and followed by *,
-      // because * / / * is an end and start of a C comment
-      if (p[1] == '/' && (p == line || p[-1] != '*' || p[2] != '*')) {
+      // Accept a double /, unless it's preceded with * and followed by *,
+      // because * / / * is an end and start of a C comment.
+      // Only accept the position if it is not inside a string.
+      if (p[1] == '/' && (p == line || p[-1] != '*' || p[2] != '*')
+          && !is_pos_in_string(line, (colnr_T)(p - line))) {
         break;
       }
       ++p;
diff --git a/src/nvim/testdir/test_cindent.vim b/src/nvim/testdir/test_cindent.vim
index 6554d034d3..5dc54111e7 100644
--- a/src/nvim/testdir/test_cindent.vim
+++ b/src/nvim/testdir/test_cindent.vim
@@ -1707,9 +1707,9 @@ func Test_cindent_1()
   #endif
 
   int y;		// comment
-  // comment
+			// comment
 
-  // comment
+			// comment
 
   {
   	Constructor(int a,
diff --git a/src/nvim/testdir/test_textformat.vim b/src/nvim/testdir/test_textformat.vim
index bf0706a0c2..052c32214d 100644
--- a/src/nvim/testdir/test_textformat.vim
+++ b/src/nvim/testdir/test_textformat.vim
@@ -196,6 +196,104 @@ func Test_text_format()
   enew!
 endfunc
 
+func Test_format_c_comment()
+  new
+  setl ai cindent tw=40 et fo=croql
+  let text =<< trim END
+      var = 2345;  // asdf asdf asdf asdf asdf asdf asdf asdf asdf asdf
+  END
+  call setline(1, text)
+  normal gql
+  let expected =<< trim END
+      var = 2345;  // asdf asdf asdf asdf asdf
+                   // asdf asdf asdf asdf asdf
+  END
+  call assert_equal(expected, getline(1, '$'))
+
+  %del
+  let text =<< trim END
+      var = 2345;  // asdf asdf asdf asdf asdf asdf asdf asdf asdf asdf asdf asdf
+  END
+  call setline(1, text)
+  normal gql
+  let expected =<< trim END
+      var = 2345;  // asdf asdf asdf asdf asdf
+                   // asdf asdf asdf asdf asdf
+                   // asdf asdf
+  END
+  call assert_equal(expected, getline(1, '$'))
+
+  %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, '$'))
+
+  " Using "o" repeats the line comment, "O" does not.
+  %del
+  let text =<< trim END
+      nop;
+      val = val;      // This is a comment
+  END
+  call setline(1, text)
+  normal 2Go
+  let expected =<< trim END
+      nop;
+      val = val;      // This is a comment
+                      //
+  END
+  call assert_equal(expected, getline(1, '$'))
+  normal 2GO
+  let expected =<< trim END
+      nop;
+
+      val = val;      // This is a comment
+                      //
+  END
+  call assert_equal(expected, getline(1, '$'))
+
+  " Using "o" does not repeat a comment in a string
+  %del
+  let text =<< trim END
+      nop;
+      val = " // This is not a comment";
+  END
+  call setline(1, text)
+  normal 2Gox
+  let expected =<< trim END
+      nop;
+      val = " // This is not a comment";
+      x
+  END
+  call assert_equal(expected, getline(1, '$'))
+
+  " Using CTRL-U after "o" fixes the indent
+  %del
+  let text =<< trim END
+      {
+         val = val;      // This is a comment
+  END
+  call setline(1, text)
+  exe "normal! 2Go\<C-U>x\<Esc>"
+  let expected =<< trim END
+      {
+         val = val;      // This is a comment
+         x
+  END
+  call assert_equal(expected, getline(1, '$'))
+
+  bwipe!
+endfunc
+
 " Tests for :right, :center and :left on text with embedded TAB.
 func Test_format_align()
   enew!