Teach etags new interpreters for some languages

* lib-src/etags.c (Erlang_interpreters, Lua_interpreters)
(Prolog_interpreters, Python_interpreters, Ruby_interpreters): New
static variables.
(lang_names): Use them to set interpreters for Erlang, Lua,
Prolog, Python, and Ruby.
(find_entries): Support "/usr/bin/env FOO" form of specifying an
interpreter.

* test/manual/etags/perl-src/htlmify-cystic: Modify the has-bang
line to test the "env FOO" interpreter spec.  (Bug#30075)
* test/manual/etags/ETAGS.good_1:
* test/manual/etags/ETAGS.good_2:
* test/manual/etags/ETAGS.good_3:
* test/manual/etags/ETAGS.good_4:
* test/manual/etags/ETAGS.good_5:
* test/manual/etags/ETAGS.good_6: Adapt to latest changes in test
files.

lib-src/etags.c

@@ -630,6 +630,8 @@ static const char *Erlang_suffixes [] =
 static const char Erlang_help [] =
 "In Erlang code, the tags are the functions, records and macros\n\
 defined in the file.";
+static const char *Erlang_interpreters [] =
+  { "escript", NULL };
 
 const char *Forth_suffixes [] =
   { "fth", "tok", NULL };
@@ -666,6 +668,8 @@ static const char *Lua_suffixes [] =
   { "lua", "LUA", NULL };
 static const char Lua_help [] =
 "In Lua scripts, all functions are tags.";
+static const char *Lua_interpreters [] =
+  { "lua", NULL };
 
 static const char *Makefile_filenames [] =
   { "Makefile", "makefile", "GNUMakefile", "Makefile.in", "Makefile.am", NULL};
@@ -721,12 +725,16 @@ static const char *Prolog_suffixes [] =
 static const char Prolog_help [] =
 "In Prolog code, tags are predicates and rules at the beginning of\n\
 line.";
+static const char *Prolog_interpreters [] =
+  { "gprolog", "pl", "yap", "swipl", "prolog", NULL };
 
 static const char *Python_suffixes [] =
   { "py", NULL };
 static const char Python_help [] =
 "In Python code, 'def' or 'class' at the beginning of a line\n\
 generate a tag.";
+static const char *Python_interpreters [] =
+  { "python", NULL };
 
 static const char *Ruby_suffixes [] =
   { "rb", "ru", "rbw", NULL };
@@ -735,6 +743,8 @@ static const char *Ruby_filenames [] =
 static const char Ruby_help [] =
   "In Ruby code, 'def' or 'class' or 'module' at the beginning of\n\
 a line generate a tag.  Constants also generate a tag.";
+static const char *Ruby_interpreters [] =
+  { "ruby", NULL };
 
 /* Can't do the `SCM' or `scm' prefix with a version number. */
 static const char *Scheme_suffixes [] =
@@ -798,14 +808,15 @@ static language lang_names [] =
   { "c++",       Cplusplus_help, Cplusplus_entries, Cplusplus_suffixes },
   { "c*",        no_lang_help,   Cstar_entries,     Cstar_suffixes     },
   { "cobol",     Cobol_help,     Cobol_paragraphs,  Cobol_suffixes     },
-  { "erlang",    Erlang_help,    Erlang_functions,  Erlang_suffixes    },
+  { "erlang",    Erlang_help,    Erlang_functions,  Erlang_suffixes,
+                 NULL,           Erlang_interpreters },
   { "forth",     Forth_help,     Forth_words,       Forth_suffixes     },
   { "fortran",   Fortran_help,   Fortran_functions, Fortran_suffixes   },
   { "go",        Go_help,        Go_functions,      Go_suffixes        },
   { "html",      HTML_help,      HTML_labels,       HTML_suffixes      },
   { "java",      Cjava_help,     Cjava_entries,     Cjava_suffixes     },
   { "lisp",      Lisp_help,      Lisp_functions,    Lisp_suffixes      },
-  { "lua",       Lua_help,       Lua_functions,     Lua_suffixes       },
+  { "lua",       Lua_help,Lua_functions,Lua_suffixes,NULL,Lua_interpreters},
   { "makefile",  Makefile_help,Makefile_targets,NULL,Makefile_filenames},
   { "objc",      Objc_help,      plain_C_entries,   Objc_suffixes      },
   { "pascal",    Pascal_help,    Pascal_functions,  Pascal_suffixes    },
@@ -813,9 +824,12 @@ static language lang_names [] =
   { "php",       PHP_help,       PHP_functions,     PHP_suffixes       },
   { "postscript",PS_help,        PS_functions,      PS_suffixes        },
   { "proc",      no_lang_help,   plain_C_entries,   plain_C_suffixes   },
-  { "prolog",    Prolog_help,    Prolog_functions,  Prolog_suffixes    },
-  { "python",    Python_help,    Python_functions,  Python_suffixes    },
-  { "ruby",      Ruby_help,Ruby_functions,Ruby_suffixes,Ruby_filenames },
+  { "prolog",    Prolog_help,    Prolog_functions,  Prolog_suffixes,
+                 NULL,           Prolog_interpreters },
+  { "python",    Python_help,    Python_functions,  Python_suffixes,
+                 NULL,           Python_interpreters },
+  { "ruby",      Ruby_help,      Ruby_functions,    Ruby_suffixes,
+                 Ruby_filenames, Ruby_interpreters },
   { "scheme",    Scheme_help,    Scheme_functions,  Scheme_suffixes    },
   { "tex",       TeX_help,       TeX_commands,      TeX_suffixes       },
   { "texinfo",   Texinfo_help,   Texinfo_nodes,     Texinfo_suffixes   },
@@ -1796,6 +1810,13 @@ find_entries (FILE *inf)
       else
 	lp = skip_spaces (lb.buffer + 2);
       cp = skip_non_spaces (lp);
+      /* If the "interpreter" turns out to be "env", the real interpreter is
+	 the next word.  */
+      if (cp > lp && strneq (lp, "env", cp - lp))
+	{
+	  lp = skip_spaces (cp);
+	  cp = skip_non_spaces (lp);
+	}
       *cp = '\0';
 
       if (strlen (lp) > 0)

test/manual/etags/perl-src/htlmify-cystic

@@ -1,4 +1,4 @@
-#! /uns/bin/perl -w
+#! /un/bin/env perl
 
 # htmlify-cystic-l-faq:  turn text version of cystic-l faq into html
 # run like this:   htmlify-cystic-l-faq < cystic-l-faq-all