diff --git a/src/nvim/quickfix.c b/src/nvim/quickfix.c
index f38cf231fe..66cc184177 100644
--- a/src/nvim/quickfix.c
+++ b/src/nvim/quickfix.c
@@ -157,7 +157,8 @@ enum {
   QF_OK = 1,
   QF_END_OF_INPUT = 2,
   QF_NOMEM = 3,
-  QF_IGNORE_LINE = 4
+  QF_IGNORE_LINE = 4,
+  QF_MULTISCAN = 5,
 };
 
 typedef struct {
@@ -723,21 +724,17 @@ static int qf_parse_line(qf_info_T *qi, int qf_idx, char_u *linebuf,
                          size_t linelen, efm_T *fmt_first, qffields_T *fields)
 {
   efm_T *fmt_ptr;
-  size_t len;
-  int    i;
   int    idx = 0;
   char_u *tail = NULL;
-  regmatch_T regmatch;
   qf_list_T *qfl = &qi->qf_lists[qf_idx];
-
-  // Always ignore case when looking for a matching error.
-  regmatch.rm_ic = true;
+  int status;
 
 restofline:
   // If there was no %> item start at the first pattern
   if (fmt_start == NULL) {
     fmt_ptr = fmt_first;
   } else {
+    // Otherwise start from the last used pattern.
     fmt_ptr = fmt_start;
     fmt_start = NULL;
   }
@@ -747,151 +744,13 @@ restofline:
   fields->valid = true;
   for (; fmt_ptr != NULL; fmt_ptr = fmt_ptr->next) {
     idx = fmt_ptr->prefix;
-    if (qfl->qf_multiscan && vim_strchr((char_u *)"OPQ", idx) == NULL) {
-      continue;
+    status = qf_parse_get_fields(linebuf, linelen, fmt_ptr, fields,
+                                 qfl->qf_multiline, qfl->qf_multiscan,
+                                 &tail);
+    if (status == QF_NOMEM) {
+      return status;
     }
-    fields->namebuf[0] = NUL;
-    fields->module[0] = NUL;
-    fields->pattern[0] = NUL;
-    if (!qfl->qf_multiscan) {
-      fields->errmsg[0] = NUL;
-    }
-    fields->lnum = 0;
-    fields->col = 0;
-    fields->use_viscol = false;
-    fields->enr = -1;
-    fields->type = 0;
-    tail = NULL;
-
-    regmatch.regprog = fmt_ptr->prog;
-    int r = vim_regexec(&regmatch, linebuf, (colnr_T)0);
-    fmt_ptr->prog = regmatch.regprog;
-    if (r) {
-      if ((idx == 'C' || idx == 'Z') && !qfl->qf_multiline) {
-        continue;
-      }
-      if (vim_strchr((char_u *)"EWI", idx) != NULL) {
-        fields->type = (char_u)idx;
-      } else {
-        fields->type = 0;
-      }
-      // Extract error message data from matched line.
-      // We check for an actual submatch, because "\[" and "\]" in
-      // the 'errorformat' may cause the wrong submatch to be used.
-      if ((i = (int)fmt_ptr->addr[0]) > 0) {  // %f
-        if (regmatch.startp[i] == NULL || regmatch.endp[i] == NULL) {
-          continue;
-        }
-        // Expand ~/file and $HOME/file to full path.
-        char_u c = *regmatch.endp[i];
-        *regmatch.endp[i] = NUL;
-        expand_env(regmatch.startp[i], fields->namebuf, CMDBUFFSIZE);
-        *regmatch.endp[i] = c;
-
-        if (vim_strchr((char_u *)"OPQ", idx) != NULL
-            && !os_path_exists(fields->namebuf)) {
-          continue;
-        }
-      }
-      if ((i = (int)fmt_ptr->addr[1]) > 0) {                  // %n
-        if (regmatch.startp[i] == NULL) {
-          continue;
-        }
-        fields->enr = (int)atol((char *)regmatch.startp[i]);
-      }
-      if ((i = (int)fmt_ptr->addr[2]) > 0) {                  // %l
-        if (regmatch.startp[i] == NULL) {
-          continue;
-        }
-        fields->lnum = atol((char *)regmatch.startp[i]);
-      }
-      if ((i = (int)fmt_ptr->addr[3]) > 0) {                  // %c
-        if (regmatch.startp[i] == NULL) {
-          continue;
-        }
-        fields->col = (int)atol((char *)regmatch.startp[i]);
-      }
-      if ((i = (int)fmt_ptr->addr[4]) > 0) {                  // %t
-        if (regmatch.startp[i] == NULL) {
-          continue;
-        }
-        fields->type = *regmatch.startp[i];
-      }
-      if (fmt_ptr->flags == '+' && !qfl->qf_multiscan) {      // %+
-        if (linelen >= fields->errmsglen) {
-          // linelen + null terminator
-          fields->errmsg = xrealloc(fields->errmsg, linelen + 1);
-          fields->errmsglen = linelen + 1;
-        }
-        STRLCPY(fields->errmsg, linebuf, linelen + 1);
-      } else if ((i = (int)fmt_ptr->addr[5]) > 0) {           // %m
-        if (regmatch.startp[i] == NULL || regmatch.endp[i] == NULL) {
-          continue;
-        }
-        len = (size_t)(regmatch.endp[i] - regmatch.startp[i]);
-        if (len >= fields->errmsglen) {
-          // len + null terminator
-          fields->errmsg = xrealloc(fields->errmsg, len + 1);
-          fields->errmsglen = len + 1;
-        }
-        STRLCPY(fields->errmsg, regmatch.startp[i], len + 1);
-      }
-      if ((i = (int)fmt_ptr->addr[6]) > 0) {                  // %r
-        if (regmatch.startp[i] == NULL) {
-          continue;
-        }
-        tail = regmatch.startp[i];
-      }
-      if ((i = (int)fmt_ptr->addr[7]) > 0) {                  // %p
-        char_u      *match_ptr;
-
-        if (regmatch.startp[i] == NULL || regmatch.endp[i] == NULL) {
-          continue;
-        }
-        fields->col = 0;
-        for (match_ptr = regmatch.startp[i];
-             match_ptr != regmatch.endp[i]; match_ptr++) {
-          fields->col++;
-          if (*match_ptr == TAB) {
-            fields->col += 7;
-            fields->col -= fields->col % 8;
-          }
-        }
-        fields->col++;
-        fields->use_viscol = true;
-      }
-      if ((i = (int)fmt_ptr->addr[8]) > 0) {                  // %v
-        if (regmatch.startp[i] == NULL) {
-          continue;
-        }
-        fields->col = (int)atol((char *)regmatch.startp[i]);
-        fields->use_viscol = true;
-      }
-      if ((i = (int)fmt_ptr->addr[9]) > 0) {                  // %s
-        if (regmatch.startp[i] == NULL || regmatch.endp[i] == NULL) {
-          continue;
-        }
-        len = (size_t)(regmatch.endp[i] - regmatch.startp[i]);
-        if (len > CMDBUFFSIZE - 5) {
-          len = CMDBUFFSIZE - 5;
-        }
-        STRCPY(fields->pattern, "^\\V");
-        xstrlcat((char *)fields->pattern, (char *)regmatch.startp[i],
-                 CMDBUFFSIZE+1);
-        fields->pattern[len + 3] = '\\';
-        fields->pattern[len + 4] = '$';
-        fields->pattern[len + 5] = NUL;
-      }
-      if ((i = (int)fmt_ptr->addr[10]) > 0) {  // %o
-        if (regmatch.startp[i] == NULL) {
-          continue;
-        }
-        len = (size_t)(regmatch.endp[i] - regmatch.startp[i]);
-        if (len > CMDBUFFSIZE) {
-          len = CMDBUFFSIZE;
-        }
-        xstrlcat((char *)fields->module, (char *)regmatch.startp[i], len);
-      }
+    if (status == QF_OK) {
       break;
     }
   }
@@ -899,30 +758,16 @@ restofline:
 
   if (fmt_ptr == NULL || idx == 'D' || idx == 'X') {
     if (fmt_ptr != NULL) {
-      if (idx == 'D') {                               // enter directory
-        if (*fields->namebuf == NUL) {
-          EMSG(_("E379: Missing or empty directory name"));
-          return QF_FAIL;
-        }
-        qfl->qf_directory = qf_push_dir(fields->namebuf, &qfl->qf_dir_stack,
-                                        false);
-        if (qfl->qf_directory == NULL) {
-          return QF_FAIL;
-        }
-      } else if (idx == 'X') {                        // leave directory
-        qfl->qf_directory = qf_pop_dir(&qfl->qf_dir_stack);
+      // 'D' and 'X' directory specifiers.
+      status = qf_parse_dir_pfx(idx, fields, qfl);
+      if (status != QF_OK) {
+        return status;
       }
     }
-    fields->namebuf[0] = NUL;                // no match found, remove file name
-    fields->lnum = 0;                        // don't jump to this line
-    fields->valid = false;
-    if (linelen >= fields->errmsglen) {
-      // linelen + null terminator
-      fields->errmsg = xrealloc(fields->errmsg, linelen + 1);
-      fields->errmsglen = linelen + 1;
+    status = qf_parse_line_nomatch(linebuf, linelen, fields);
+    if (status != QF_OK) {
+      return status;
     }
-    // copy whole line to error message
-    STRLCPY(fields->errmsg, linebuf, linelen + 1);
     if (fmt_ptr == NULL) {
       qfl->qf_multiline = qfl->qf_multiignore = false;
     }
@@ -935,63 +780,17 @@ restofline:
     if (vim_strchr((char_u *)"AEWI", idx) != NULL) {
       qfl->qf_multiline = true;     // start of a multi-line message
       qfl->qf_multiignore = false;  // reset continuation
-    } else if (vim_strchr((char_u *)"CZ", idx)
-               != NULL) {  // continuation of multi-line msg
-      if (!qfl->qf_multiignore) {
-        qfline_T *qfprev = qfl->qf_last;
-        if (qfprev == NULL) {
-          return QF_FAIL;
-        }
-        if (*fields->errmsg) {
-          size_t textlen = STRLEN(qfprev->qf_text);
-          qfprev->qf_text = xrealloc(qfprev->qf_text,
-                                     textlen + STRLEN(fields->errmsg) + 2);
-          qfprev->qf_text[textlen] = '\n';
-          STRCPY(qfprev->qf_text + textlen + 1, fields->errmsg);
-        }
-        if (qfprev->qf_nr == -1) {
-          qfprev->qf_nr = fields->enr;
-        }
-        if (vim_isprintc(fields->type) && !qfprev->qf_type) {
-          qfprev->qf_type = fields->type;  // only printable chars allowed
-        }
-        if (!qfprev->qf_lnum) {
-          qfprev->qf_lnum = fields->lnum;
-        }
-        if (!qfprev->qf_col) {
-          qfprev->qf_col = fields->col;
-        }
-        qfprev->qf_viscol = fields->use_viscol;
-        if (!qfprev->qf_fnum) {
-          qfprev->qf_fnum = qf_get_fnum(qi, qf_idx, qfl->qf_directory,
-                                        *fields->namebuf || qfl->qf_directory
-                                        ? fields->namebuf
-                                        : qfl->qf_currfile && fields->valid
-                                        ? qfl->qf_currfile : 0);
-        }
+    } else if (vim_strchr((char_u *)"CZ", idx) != NULL) {
+      // continuation of multi-line msg
+      status = qf_parse_multiline_pfx(qi, qf_idx, idx, qfl, fields);
+      if (status != QF_OK) {
+        return status;
       }
-      if (idx == 'Z') {
-        qfl->qf_multiline = qfl->qf_multiignore = false;
-      }
-
-      line_breakcheck();
-      return QF_IGNORE_LINE;
     } else if (vim_strchr((char_u *)"OPQ", idx) != NULL) {
       // global file names
-      fields->valid = false;
-      if (*fields->namebuf == NUL || os_path_exists(fields->namebuf)) {
-        if (*fields->namebuf && idx == 'P') {
-          qfl->qf_currfile = qf_push_dir(fields->namebuf, &qfl->qf_file_stack,
-                                         true);
-        } else if (idx == 'Q') {
-          qfl->qf_currfile = qf_pop_dir(&qfl->qf_file_stack);
-        }
-        *fields->namebuf = NUL;
-        if (tail && *tail) {
-          STRMOVE(IObuff, skipwhite(tail));
-          qfl->qf_multiscan = true;
-          goto restofline;
-        }
+      status = qf_parse_file_pfx(idx, fields, qfl, tail);
+      if (status == QF_MULTISCAN) {
+        goto restofline;
       }
     }
     if (fmt_ptr->flags == '-') {  // generally exclude this line
@@ -1207,6 +1006,8 @@ qf_init_end:
   return retval;
 }
 
+/// Set the title of the specified quickfix list. Frees the previous title.
+/// Prepends ':' to the title.
 static void qf_store_title(qf_info_T *qi, int qf_idx, char_u *title)
 {
   xfree(qi->qf_lists[qf_idx].qf_title);
@@ -1250,9 +1051,299 @@ static void qf_new_list(qf_info_T *qi, char_u *qf_title)
   qi->qf_lists[qi->qf_curlist].qf_id = ++last_qf_id;
 }
 
-/*
- * Free a location list
- */
+/// Parse the error format matches in 'regmatch' and set the values in 'fields'.
+/// fmt_ptr contains the 'efm' format specifiers/prefixes that have a match.
+/// Returns QF_OK if all the matches are successfully parsed. On failure,
+/// returns QF_FAIL or QF_NOMEM.
+static int qf_parse_match(char_u *linebuf, size_t linelen, efm_T *fmt_ptr,
+                          regmatch_T *regmatch, qffields_T *fields,
+                          int qf_multiline, int qf_multiscan, char_u **tail)
+{
+  char_u idx = fmt_ptr->prefix;
+  int i;
+  size_t len;
+
+  if ((idx == 'C' || idx == 'Z') && !qf_multiline) {
+    return QF_FAIL;
+  }
+  if (vim_strchr((char_u *)"EWI", idx) != NULL) {
+    fields->type = idx;
+  } else {
+    fields->type = 0;
+  }
+
+  // Extract error message data from matched line.
+  // We check for an actual submatch, because "\[" and "\]" in
+  // the 'errorformat' may cause the wrong submatch to be used.
+  if ((i = (int)fmt_ptr->addr[0]) > 0) {  // %f
+    if (regmatch->startp[i] == NULL || regmatch->endp[i] == NULL) {
+      return QF_FAIL;
+    }
+
+    // Expand ~/file and $HOME/file to full path.
+    char_u c = *regmatch->endp[i];
+    *regmatch->endp[i] = NUL;
+    expand_env(regmatch->startp[i], fields->namebuf, CMDBUFFSIZE);
+    *regmatch->endp[i] = c;
+
+    if (vim_strchr((char_u *)"OPQ", idx) != NULL
+        && !os_path_exists(fields->namebuf)) {
+      return QF_FAIL;
+    }
+  }
+  if ((i = (int)fmt_ptr->addr[1]) > 0) {  // %n
+    if (regmatch->startp[i] == NULL) {
+      return QF_FAIL;
+    }
+    fields->enr = (int)atol((char *)regmatch->startp[i]);
+  }
+  if ((i = (int)fmt_ptr->addr[2]) > 0) {  // %l
+    if (regmatch->startp[i] == NULL) {
+      return QF_FAIL;
+    }
+    fields->lnum = atol((char *)regmatch->startp[i]);
+  }
+  if ((i = (int)fmt_ptr->addr[3]) > 0) {  // %c
+    if (regmatch->startp[i] == NULL) {
+      return QF_FAIL;
+    }
+    fields->col = (int)atol((char *)regmatch->startp[i]);
+  }
+  if ((i = (int)fmt_ptr->addr[4]) > 0) {  // %t
+    if (regmatch->startp[i] == NULL) {
+      return QF_FAIL;
+    }
+    fields->type = *regmatch->startp[i];
+  }
+  if (fmt_ptr->flags == '+' && !qf_multiscan) {  // %+
+    if (linelen >= fields->errmsglen) {
+      // linelen + null terminator
+      fields->errmsg = xrealloc(fields->errmsg, linelen + 1);
+      fields->errmsglen = linelen + 1;
+    }
+    STRLCPY(fields->errmsg, linebuf, linelen + 1);
+  } else if ((i = (int)fmt_ptr->addr[5]) > 0) {  // %m
+    if (regmatch->startp[i] == NULL || regmatch->endp[i] == NULL) {
+      return QF_FAIL;
+    }
+    len = (size_t)(regmatch->endp[i] - regmatch->startp[i]);
+    if (len >= fields->errmsglen) {
+      // len + null terminator
+      fields->errmsg = xrealloc(fields->errmsg, len + 1);
+      fields->errmsglen = len + 1;
+    }
+    STRLCPY(fields->errmsg, regmatch->startp[i], len + 1);
+  }
+  if ((i = (int)fmt_ptr->addr[6]) > 0) {  // %r
+    if (regmatch->startp[i] == NULL) {
+      return QF_FAIL;
+    }
+    *tail = regmatch->startp[i];
+  }
+  if ((i = (int)fmt_ptr->addr[7]) > 0) {  // %p
+    if (regmatch->startp[i] == NULL || regmatch->endp[i] == NULL) {
+      return QF_FAIL;
+    }
+    fields->col = 0;
+    char_u *match_ptr;
+    for (match_ptr = regmatch->startp[i]; match_ptr != regmatch->endp[i];
+         match_ptr++) {
+      fields->col++;
+      if (*match_ptr == TAB) {
+        fields->col += 7;
+        fields->col -= fields->col % 8;
+      }
+    }
+    fields->col++;
+    fields->use_viscol = true;
+  }
+  if ((i = (int)fmt_ptr->addr[8]) > 0) {  // %v
+    if (regmatch->startp[i] == NULL) {
+      return QF_FAIL;
+    }
+    fields->col = (int)atol((char *)regmatch->startp[i]);
+    fields->use_viscol = true;
+  }
+  if ((i = (int)fmt_ptr->addr[9]) > 0) {  // %s
+    if (regmatch->startp[i] == NULL || regmatch->endp[i] == NULL) {
+      return QF_FAIL;
+    }
+    len = (size_t)(regmatch->endp[i] - regmatch->startp[i]);
+    if (len > CMDBUFFSIZE - 5) {
+      len = CMDBUFFSIZE - 5;
+    }
+    STRCPY(fields->pattern, "^\\V");
+    STRNCAT(fields->pattern, regmatch->startp[i], len);
+    fields->pattern[len + 3] = '\\';
+    fields->pattern[len + 4] = '$';
+    fields->pattern[len + 5] = NUL;
+  }
+  if ((i = (int)fmt_ptr->addr[10]) > 0) {  // %o
+    if (regmatch->startp[i] == NULL || regmatch->endp[i] == NULL) {
+      return QF_FAIL;
+    }
+    len = (size_t)(regmatch->endp[i] - regmatch->startp[i]);
+    if (len > CMDBUFFSIZE) {
+      len = CMDBUFFSIZE;
+    }
+    STRNCAT(fields->module, regmatch->startp[i], len);
+  }
+
+  return QF_OK;
+}
+
+/// Parse an error line in 'linebuf' using a single error format string in
+/// 'fmt_ptr->prog' and return the matching values in 'fields'.
+/// Returns QF_OK if the efm format matches completely and the fields are
+/// successfully copied. Otherwise returns QF_FAIL or QF_NOMEM.
+static int qf_parse_get_fields(char_u *linebuf, size_t linelen, efm_T *fmt_ptr,
+                               qffields_T *fields, int qf_multiline,
+                               int qf_multiscan, char_u **tail)
+{
+  regmatch_T regmatch;
+  int status = QF_FAIL;
+  int r;
+
+  if (qf_multiscan && vim_strchr((char_u *)"OPQ", fmt_ptr->prefix) == NULL) {
+    return QF_FAIL;
+  }
+
+  fields->namebuf[0] = NUL;
+  fields->module[0] = NUL;
+  fields->pattern[0] = NUL;
+  if (!qf_multiscan) {
+    fields->errmsg[0] = NUL;
+  }
+  fields->lnum = 0;
+  fields->col = 0;
+  fields->use_viscol = false;
+  fields->enr = -1;
+  fields->type = 0;
+  *tail = NULL;
+
+  regmatch.regprog = fmt_ptr->prog;
+  r = vim_regexec(&regmatch, linebuf, (colnr_T)0);
+  fmt_ptr->prog = regmatch.regprog;
+  if (r) {
+    status = qf_parse_match(linebuf, linelen, fmt_ptr, &regmatch, fields,
+                            qf_multiline, qf_multiscan, tail);
+  }
+
+  return status;
+}
+
+/// Parse directory error format prefixes (%D and %X).
+/// Push and pop directories from the directory stack when scanning directory
+/// names.
+static int qf_parse_dir_pfx(int idx, qffields_T *fields, qf_list_T *qfl)
+{
+  if (idx == 'D') {  // enter directory
+    if (*fields->namebuf == NUL) {
+      EMSG(_("E379: Missing or empty directory name"));
+      return QF_FAIL;
+    }
+    qfl->qf_directory = qf_push_dir(fields->namebuf, &qfl->qf_dir_stack, false);
+    if (qfl->qf_directory == NULL) {
+      return QF_FAIL;
+    }
+  } else if (idx == 'X') {  // leave directory
+    qfl->qf_directory = qf_pop_dir(&qfl->qf_dir_stack);
+  }
+
+  return QF_OK;
+}
+
+/// Parse global file name error format prefixes (%O, %P and %Q).
+static int qf_parse_file_pfx(int idx, qffields_T *fields, qf_list_T *qfl,
+                             char_u *tail)
+{
+  fields->valid = false;
+  if (*fields->namebuf == NUL || os_path_exists(fields->namebuf)) {
+    if (*fields->namebuf && idx == 'P') {
+      qfl->qf_currfile = qf_push_dir(fields->namebuf, &qfl->qf_file_stack,
+                                     true);
+    } else if (idx == 'Q') {
+      qfl->qf_currfile = qf_pop_dir(&qfl->qf_file_stack);
+    }
+    *fields->namebuf = NUL;
+    if (tail && *tail) {
+      STRMOVE(IObuff, skipwhite(tail));
+      qfl->qf_multiscan = true;
+      return QF_MULTISCAN;
+    }
+  }
+
+  return QF_OK;
+}
+
+/// Parse a non-error line (a line which doesn't match any of the error
+/// format in 'efm').
+static int qf_parse_line_nomatch(char_u *linebuf, size_t linelen,
+                                 qffields_T *fields)
+{
+  fields->namebuf[0] = NUL;   // no match found, remove file name
+  fields->lnum = 0;           // don't jump to this line
+  fields->valid = false;
+  if (linelen >= fields->errmsglen) {
+    // linelen + null terminator
+    fields->errmsg = xrealloc(fields->errmsg, linelen + 1);
+    fields->errmsglen = linelen + 1;
+  }
+  // copy whole line to error message
+  STRLCPY(fields->errmsg, linebuf, linelen + 1);
+
+  return QF_OK;
+}
+
+/// Parse multi-line error format prefixes (%C and %Z)
+static int qf_parse_multiline_pfx(qf_info_T *qi, int qf_idx, int idx,
+                                  qf_list_T *qfl, qffields_T *fields)
+{
+  if (!qfl->qf_multiignore) {
+    qfline_T *qfprev = qfl->qf_last;
+
+    if (qfprev == NULL) {
+      return QF_FAIL;
+    }
+    if (*fields->errmsg && !qfl->qf_multiignore) {
+      size_t textlen = strlen((char *)qfprev->qf_text);
+      size_t errlen  = strlen((char *)fields->errmsg);
+      qfprev->qf_text = xrealloc(qfprev->qf_text, textlen + errlen + 2);
+      qfprev->qf_text[textlen] = '\n';
+      STRCPY(qfprev->qf_text + textlen + 1, fields->errmsg);
+    }
+    if (qfprev->qf_nr == -1) {
+      qfprev->qf_nr = fields->enr;
+    }
+    if (vim_isprintc(fields->type) && !qfprev->qf_type) {
+      // only printable chars allowed
+      qfprev->qf_type = fields->type;
+    }
+
+    if (!qfprev->qf_lnum) {
+      qfprev->qf_lnum = fields->lnum;
+    }
+    if (!qfprev->qf_col) {
+      qfprev->qf_col = fields->col;
+    }
+    qfprev->qf_viscol = fields->use_viscol;
+    if (!qfprev->qf_fnum) {
+      qfprev->qf_fnum = qf_get_fnum(qi, qf_idx, qfl->qf_directory,
+                                    *fields->namebuf || qfl->qf_directory
+                                    ? fields->namebuf
+                                    : qfl->qf_currfile && fields->valid
+                                    ? qfl->qf_currfile : 0);
+    }
+  }
+  if (idx == 'Z') {
+    qfl->qf_multiline = qfl->qf_multiignore = false;
+  }
+  line_breakcheck();
+
+  return QF_IGNORE_LINE;
+}
+
+/// Free a location list.
 static void ll_free_all(qf_info_T **pqi)
 {
   int i;
@@ -1272,6 +1363,7 @@ static void ll_free_all(qf_info_T **pqi)
   }
 }
 
+/// Free all the quickfix/location lists in the stack.
 void qf_free_all(win_T *wp)
 {
   int i;
@@ -2497,6 +2589,8 @@ static void qf_fmt_text(char_u *text, char_u *buf, int bufsize)
   buf[i] = NUL;
 }
 
+/// Display information (list number, list size and the title) about a
+/// quickfix/location list.
 static void qf_msg(qf_info_T *qi, int which, char *lead)
 {
   char *title = (char *)qi->qf_lists[which].qf_title;
@@ -2566,6 +2660,7 @@ void qf_age(exarg_T *eap)
   qf_update_buffer(qi, NULL);
 }
 
+/// Display the information about all the quickfix/location lists in the stack.
 void qf_history(exarg_T *eap)
 {
   qf_info_T *qi = &ql_info;
@@ -5016,6 +5111,7 @@ int set_errorlist(win_T *wp, list_T *list, int action, char_u *title,
   return retval;
 }
 
+/// Mark the context as in use for all the lists in a quickfix stack.
 static bool mark_quickfix_ctx(qf_info_T *qi, int copyID)
 {
   bool abort = false;
@@ -5292,7 +5388,7 @@ void ex_helpgrep(exarg_T *eap)
     // Create a new quickfix list.
     qf_new_list(qi, *eap->cmdlinep);
 
-    /* Go through all directories in 'runtimepath' */
+    // Go through all the directories in 'runtimepath'
     p = p_rtp;
     while (*p != NUL && !got_int) {
       copy_option_part(&p, NameBuff, MAXPATHL, ",");