Fix tagging of class members in C-like OO languages

* lib-src/etags.c (longopts): Add new option --class-qualify and
its shorthand -Q.
(print_help): Add help text for --class-qualify.
(main): Add handling of -Q.
(consider_token, C_entries) <omethodparm>: Append argument types
to Objective C methods only if --class-qualify was specified.
Qualify C++, Objective C, and Java class members with their class
names only if --class-qualify was specified.
(C_entries): If --class-qualify was not specified, remove the
namespace and class qualifiers from tag names of C++ methods.
This allows to use etags.el as xref back-end without the
tag-symbol-match-p method, which greatly increases the number of
potentially false positives.  (Bug#20629)

* doc/man/etags.1: Update to document the new --class-qualify
option.

* test/etags/ETAGS.good_1:
* test/etags/ETAGS.good_2:
* test/etags/ETAGS.good_3:
* test/etags/ETAGS.good_4:
* test/etags/ETAGS.good_5:
* test/etags/CTAGS.good: Update due to changes in etags.c.

1 files changed, 79 insertions, 19 deletions

diff --git a/lib-src/etags.c b/lib-src/etags.c
index 4b99e392728..73dd5a8a405 100644
--- a/lib-src/etags.c
+++ b/lib-src/etags.c
@@ -441,6 +441,7 @@ static bool cxref_style;	/* -x: create cxref style output */
 static bool cplusplus;          /* .[hc] means C++, not C (undocumented) */
 static bool ignoreindent;       /* -I: ignore indentation in C */
 static int packages_only;       /* --packages-only: in Ada, only tag packages*/
+static int class_qualify;       /* -Q: produce class-qualified tags in C++/Java */
 
 /* STDIN is defined in LynxOS system headers */
 #ifdef STDIN
@@ -468,6 +469,7 @@ static struct option longopts[] =
   { "members",            no_argument,       &members,           1     },
   { "no-members",         no_argument,       &members,           0     },
   { "output",             required_argument, NULL,               'o'   },
+  { "class-qualify",      no_argument,       &class_qualify,     'Q'   },
   { "regex",              required_argument, NULL,               'r'   },
   { "no-regex",           no_argument,       NULL,               'R'   },
   { "ignore-case-regex",  required_argument, NULL,               'c'   },
@@ -933,6 +935,12 @@ Relative ones are stored relative to the output file's directory.\n");
         Do not create tag entries for members of structures\n\
         in some languages.");
 
+  puts ("-Q, --class-qualify\n\
+        Qualify tag names with their class name in C++, ObjC, and Java.\n\
+        This produces tag names of the form \"class::member\" for C++,\n\
+        \"class(category)\" for Objective C, and \"class.member\" for Java.\n\
+        For Objective C, this also produces class methods qualified with\n\
+        their arguments, as in \"foo:bar:baz:more\".");
   puts ("-r REGEXP, --regex=REGEXP or --regex=@regexfile\n\
         Make a tag for each line matching a regular expression pattern\n\
         in the following files.  {LANGUAGE}REGEXP uses REGEXP for LANGUAGE\n\
@@ -1050,7 +1058,7 @@ main (int argc, char **argv)
 
   /* When the optstring begins with a '-' getopt_long does not rearrange the
      non-options arguments to be at the end, but leaves them alone. */
-  optstring = concat ("-ac:Cf:Il:o:r:RSVhH",
+  optstring = concat ("-ac:Cf:Il:o:Qr:RSVhH",
                       (CTAGS) ? "BxdtTuvw" : "Di:",
                       "");
 
@@ -1139,6 +1147,9 @@ main (int argc, char **argv)
       case 'H':
         help_asked = true;
         break;
+      case 'Q':
+        class_qualify = 1;
+        break;
 
         /* Etags options */
       case 'D': constantypedefs = false;                        break;
@@ -2852,12 +2863,15 @@ consider_token (char *str, int len, int c, int *c_extp,
      case omethodparm:
        if (parlev == 0)
          {
-           int oldlen = token_name.len;
-           fvdef = fvnone;
            objdef = omethodtag;
-           linebuffer_setlen (&token_name, oldlen + len);
-           memcpy (token_name.buffer + oldlen, str, len);
-           token_name.buffer[oldlen + len] = '\0';
+           if (class_qualify)
+             {
+               int oldlen = token_name.len;
+               fvdef = fvnone;
+               linebuffer_setlen (&token_name, oldlen + len);
+               memcpy (token_name.buffer + oldlen, str, len);
+               token_name.buffer[oldlen + len] = '\0';
+             }
            return true;
          }
        return false;
@@ -3307,21 +3321,42 @@ C_entries (int c_ext, FILE *inf)
                               && nestlev > 0 && definedef == dnone)
                             /* in struct body */
                             {
-                              int len;
-                              write_classname (&token_name, qualifier);
-                              len = token_name.len;
-                              linebuffer_setlen (&token_name, len+qlen+toklen);
-                              sprintf (token_name.buffer + len, "%s%.*s",
-                                       qualifier, toklen, newlb.buffer + tokoff);
+                              if (class_qualify)
+                                {
+                                  int len;
+                                  write_classname (&token_name, qualifier);
+                                  len = token_name.len;
+                                  linebuffer_setlen (&token_name,
+                                                     len + qlen + toklen);
+                                  sprintf (token_name.buffer + len, "%s%.*s",
+                                           qualifier, toklen,
+                                           newlb.buffer + tokoff);
+                                }
+                              else
+                                {
+                                  linebuffer_setlen (&token_name, toklen);
+                                  sprintf (token_name.buffer, "%.*s",
+                                           toklen, newlb.buffer + tokoff);
+                                }
                               token.named = true;
                             }
                           else if (objdef == ocatseen)
                             /* Objective C category */
                             {
-                              int len = strlen (objtag) + 2 + toklen;
-                              linebuffer_setlen (&token_name, len);
-                              sprintf (token_name.buffer, "%s(%.*s)",
-                                       objtag, toklen, newlb.buffer + tokoff);
+                              if (class_qualify)
+                                {
+                                  int len = strlen (objtag) + 2 + toklen;
+                                  linebuffer_setlen (&token_name, len);
+                                  sprintf (token_name.buffer, "%s(%.*s)",
+                                           objtag, toklen,
+                                           newlb.buffer + tokoff);
+                                }
+                              else
+                                {
+                                  linebuffer_setlen (&token_name, toklen);
+                                  sprintf (token_name.buffer, "%.*s",
+                                           newlb.buffer + tokoff);
+                                }
                               token.named = true;
                             }
                           else if (objdef == omethodtag
@@ -3479,9 +3514,12 @@ C_entries (int c_ext, FILE *inf)
             case omethodtag:
             case omethodparm:
               objdef = omethodcolon;
-              int toklen = token_name.len;
-              linebuffer_setlen (&token_name, toklen + 1);
-              strcpy (token_name.buffer + toklen, ":");
+              if (class_qualify)
+                {
+                  int toklen = token_name.len;
+                  linebuffer_setlen (&token_name, toklen + 1);
+                  strcpy (token_name.buffer + toklen, ":");
+                }
               break;
             }
           if (structdef == stagseen)
@@ -3716,6 +3754,28 @@ C_entries (int c_ext, FILE *inf)
           switch (fvdef)
             {
             case flistseen:
+              if (cplpl && !class_qualify)
+                {
+                  /* Remove class and namespace qualifiers from the token,
+                     leaving only the method/member name.  */
+                  char *cc, *uqname = token_name.buffer;
+                  char *tok_end = token_name.buffer + token_name.len;
+
+                  for (cc = token_name.buffer; cc < tok_end; cc++)
+                    {
+                      if (*cc == ':' && cc[1] == ':')
+                        {
+                          uqname = cc + 2;
+                          cc++;
+                        }
+                    }
+                  if (uqname > token_name.buffer)
+                    {
+                      int uqlen = strlen (uqname);
+                      linebuffer_setlen (&token_name, uqlen);
+                      memmove (token_name.buffer, uqname, uqlen + 1);
+                    }
+                }
               make_C_tag (true);    /* a function */
               /* FALLTHRU */
             case fignore: