gdb: remove language_auto

I think that the language_auto enumerator and the auto_language class
can be removed.  There isn't really an "auto" language, it's only a
construct of the "set language" command to say "pick the appropriate
language automatically".  But "auto" is never the current language.  The
`current_language` points to the current effective language, and the
fact that we're in "auto language" mode is noted by the language_mode
global.

 - Change set_language to handle the "auto" (and "local", which is a
   synonym) early, instead of in the for loop.  I think it makes the two
   cases (auto vs explicit language) more clearly separated anyway.

 - Adjust add_set_language_command to hard-code the "auto" string,
   instead of using the "auto" language definition.

 - Remove auto_language, rename auto_or_unknown_language to
   unknown_language and move the bits of the existing unknown_language
   in there.

 - Remove the set_language at the end of _initialize_language.  I think
   it's not needed, because we call set_language in gdb_init, after all
   _initialize functions are called.  There is some chance that an
   _initialize function that runs after _initialize_language implicitly
   depends on current_language being set, but my testsuite runs haven't
   found anything like that.

 - Use language_unknown instead of language_auto when creating a minimal
   symbol (minimal_symbol_reader::record_full).  I think that this value
   is used to indicate that we don't know the symbol of the minimal
   symbol (yet), so language_unknown makes sense to me.  Update a
   condition accordingly in ada-lang.c.  symbol_find_demangled_name also
   appears to "normalize" this value from "unknown" to "auto", remove
   that part and update the condition to just check for
   language_unknown.

Change-Id: I47bcd6c15f607d9818f2e6e413053c2dc8ec5034
Reviewed-By: Tom Tromey <tom@tromey.com>

gdb/ada-lang.c

@@ -13700,7 +13700,7 @@ public:
 	       C++ symbols (using an old mangling scheme), such as "name__2Xn"
 	       -> "Xn::name(void)" and thus some Ada minimal symbols end up
 	       with the wrong language set.  Paper over that issue here.  */
-	    if (symbol_language == language_auto
+	    if (symbol_language == language_unknown
 		|| symbol_language == language_cplus)
 	      symbol_language = language_ada;
 

gdb/defs.h

@@ -210,7 +210,6 @@ extern void quit_serial_event_clear (void);
 enum language
   {
     language_unknown,		/* Language not known */
-    language_auto,		/* Placeholder for automatic setting */
     language_c,			/* C */
     language_objc,		/* Objective-C */
     language_rust,		/* Rust */

gdb/language.c

@@ -142,16 +142,8 @@ set_language (const char *language)
   enum language flang = language_unknown;
 
   /* "local" is a synonym of "auto".  */
-  if (strcmp (language, "local") == 0)
+  if (strcmp (language, "auto") == 0
-    language = "auto";
+      || strcmp (language, "local") == 0)
-
-  /* Search the list of languages for a match.  */
-  for (const auto &lang : language_defn::languages)
-    {
-      if (strcmp (lang->name (), language) == 0)
-	{
-	  /* Found it!  Go into manual mode, and use this language.  */
-	  if (lang->la_language == language_auto)
     {
       /* Enter auto mode.  Set to the current frame's language, if
 	 known, or fallback to the initial language.  */
@@ -172,20 +164,24 @@ set_language (const char *language)
 	set_language (flang);
       else
 	set_initial_language ();
+
       expected_language = current_language;
       return;
     }
-	  else
+
+  /* Search the list of languages for a match.  */
+  for (const auto &lang : language_defn::languages)
     {
-	      /* Enter manual mode.  Set the specified language.  */
+      if (strcmp (lang->name (), language) != 0)
+	continue;
+
+      /* Found it!  Go into manual mode, and use this language.  */
       language_mode = language_mode_manual;
       current_language = lang;
       set_range_case ();
       expected_language = current_language;
       return;
     }
-	}
-    }
 
   internal_error ("Couldn't find language `%s' in known languages list.",
 		  language);
@@ -434,9 +430,6 @@ language_enum (const char *str)
     if (strcmp (lang->name (), str) == 0)
       return lang->la_language;
 
-  if (strcmp (str, "local") == 0)
-    return language_auto;
-
   return language_unknown;
 }
 
@@ -468,22 +461,21 @@ add_set_language_command ()
   static const char **language_names;
 
   /* Build the language names array, to be used as enumeration in the
-     "set language" enum command.  +1 for "local" and +1 for NULL
+     "set language" enum command.  +3 for "auto", "local" and NULL
      termination.  */
-  language_names = new const char *[ARRAY_SIZE (language_defn::languages) + 2];
+  language_names = new const char *[ARRAY_SIZE (language_defn::languages) + 3];
 
   /* Display "auto", "local" and "unknown" first, and then the rest,
      alpha sorted.  */
   const char **language_names_p = language_names;
-  *language_names_p++ = language_def (language_auto)->name ();;
+  *language_names_p++ = "auto";
   *language_names_p++ = "local";
   *language_names_p++ = language_def (language_unknown)->name ();
   const char **sort_begin = language_names_p;
   for (const auto &lang : language_defn::languages)
     {
       /* Already handled above.  */
-      if (lang->la_language == language_auto
+      if (lang->la_language == language_unknown)
-	  || lang->la_language == language_unknown)
 	continue;
       *language_names_p++ = lang->name ();
     }
@@ -505,8 +497,7 @@ add_set_language_command ()
   for (const auto &lang : language_defn::languages)
     {
       /* Already dealt with these above.  */
-      if (lang->la_language == language_unknown
+      if (lang->la_language == language_unknown)
-	  || lang->la_language == language_auto)
 	continue;
 
       /* Note that we add the newline at the front, so we don't wind
@@ -703,15 +694,12 @@ language_defn::varobj_ops () const
   return &c_varobj_ops;
 }
 
-/* Parent class for both the "auto" and "unknown" languages.  These two
+/* Class representing the "unknown" language.  */
-   pseudo-languages are very similar so merging their implementations like
-   this makes sense.  */
 
-class auto_or_unknown_language : public language_defn
+class unknown_language : public language_defn
 {
 public:
-  auto_or_unknown_language (enum language lang)
+  unknown_language () : language_defn (language_unknown)
-    : language_defn (lang)
   { /* Nothing.  */ }
 
   /* See language.h.  */
@@ -823,40 +811,6 @@ public:
 
   const char *name_of_this () const override
   { return "this"; }
-};
-
-/* Class representing the fake "auto" language.  */
-
-class auto_language : public auto_or_unknown_language
-{
-public:
-  auto_language ()
-    : auto_or_unknown_language (language_auto)
-  { /* Nothing.  */ }
-
-  /* See language.h.  */
-
-  const char *name () const override
-  { return "auto"; }
-
-  /* See language.h.  */
-
-  const char *natural_name () const override
-  { return "Auto"; }
-};
-
-/* Single instance of the fake "auto" language.  */
-
-static auto_language auto_language_defn;
-
-/* Class representing the unknown language.  */
-
-class unknown_language : public auto_or_unknown_language
-{
-public:
-  unknown_language ()
-    : auto_or_unknown_language (language_unknown)
-  { /* Nothing.  */ }
 
   /* See language.h.  */
 
@@ -1131,7 +1085,4 @@ For Fortran the default is off; for other languages the default is on."),
 			&setlist, &showlist);
 
   add_set_language_command ();
-
-  /* Have the above take effect.  */
-  set_language (language_auto);
 }

gdb/mi/mi-parse.c

@@ -351,8 +351,7 @@ mi_parse (const char *cmd, char **token)
 	  std::string lang_name = extract_arg (&chp);
 
 	  parse->language = language_enum (lang_name.c_str ());
-	  if (parse->language == language_unknown
+	  if (parse->language == language_unknown)
-	      || parse->language == language_auto)
 	    error (_("Invalid --language argument: %s"), lang_name.c_str ());
 	}
       else

gdb/minsyms.c

@@ -1189,7 +1189,7 @@ minimal_symbol_reader::record_full (gdb::string_view name,
       m_msym_bunch = newobj;
     }
   msymbol = &m_msym_bunch->contents[m_msym_bunch_index];
-  msymbol->set_language (language_auto,
+  msymbol->set_language (language_unknown,
 			 &m_objfile->per_bfd->storage_obstack);
 
   if (copy_name)

gdb/symmisc.c

@@ -365,8 +365,7 @@ dump_symtab (struct symtab *symtab, struct ui_file *outfile)
      because certain routines used during dump_symtab() use the current
      language to print an image of the symbol.  We'll restore it later.
      But use only real languages, not placeholders.  */
-  if (symtab->language () != language_unknown
+  if (symtab->language () != language_unknown)
-      && symtab->language () != language_auto)
     {
       scoped_restore_current_language save_lang;
       set_language (symtab->language ());

gdb/symtab.c

@@ -887,10 +887,7 @@ symbol_find_demangled_name (struct general_symbol_info *gsymbol,
   gdb::unique_xmalloc_ptr<char> demangled;
   int i;
 
-  if (gsymbol->language () == language_unknown)
+  if (gsymbol->language () != language_unknown)
-    gsymbol->m_language = language_auto;
-
-  if (gsymbol->language () != language_auto)
     {
       const struct language_defn *lang = language_def (gsymbol->language ());
 
@@ -1028,7 +1025,7 @@ general_symbol_info::compute_and_set_names (gdb::string_view linkage_name,
       (*slot)->demangled = std::move (demangled_name);
       (*slot)->language = language ();
     }
-  else if (language () == language_unknown || language () == language_auto)
+  else if (language () == language_unknown)
     m_language = (*slot)->language;
 
   m_name = (*slot)->mangled.data ();