gdb/objc: make objc_demangle a member function of objc_language

Makes the objc_demangle helper function a member function of
objc_language (by renaming it to be the demangle_symbol member
function).

I also fixed some of the obvious coding standard violations in
obj_demangle, so the '&&' operators are now at the start of the line,
not the end.  Comparison to nullptr are now made explicit, as are
comparisons to the null character.

There should be no user visible changes after this commit.

gdb/ChangeLog:

	* objc-lang.c (objc_demangle): Renamed to
	objc_language::demangle_symbol, and moved later in the file.
	(objc_language::sniff_from_mangled_name): Call demangle_symbol
	member function.
	(objc_language::demangle_symbol): Defined outside of class
	declaration.  The definition is the old objc_demangle with NULL
	changed to nullptr, and if conditions relating to nullptr pointers
	or null character checks made explicit.
	* objc-lang.h (objc_demangle): Delete declaration.

gdb/objc-lang.c

@@ -216,72 +216,6 @@ value_nsstring (struct gdbarch *gdbarch, const char *ptr, int len)
   return nsstringValue;
 }
 
-/* Objective-C name demangling.  */
-
-char *
-objc_demangle (const char *mangled, int options)
-{
-  char *demangled, *cp;
-
-  if (mangled[0] == '_' &&
-     (mangled[1] == 'i' || mangled[1] == 'c') &&
-      mangled[2] == '_')
-    {
-      cp = demangled = (char *) xmalloc (strlen (mangled) + 2);
-
-      if (mangled[1] == 'i')
-	*cp++ = '-';		/* for instance method */
-      else
-	*cp++ = '+';		/* for class    method */
-
-      *cp++ = '[';		/* opening left brace  */
-      strcpy(cp, mangled+3);	/* Tack on the rest of the mangled name.  */
-
-      while (*cp && *cp == '_')
-	cp++;			/* Skip any initial underbars in class
-				   name.  */
-
-      cp = strchr(cp, '_');
-      if (!cp)	                /* Find first non-initial underbar.  */
-	{
-	  xfree(demangled);	/* not mangled name */
-	  return NULL;
-	}
-      if (cp[1] == '_')		/* Easy case: no category name.    */
-	{
-	  *cp++ = ' ';		/* Replace two '_' with one ' '.   */
-	  strcpy(cp, mangled + (cp - demangled) + 2);
-	}
-      else
-	{
-	  *cp++ = '(';		/* Less easy case: category name.  */
-	  cp = strchr(cp, '_');
-	  if (!cp)
-	    {
-	      xfree(demangled);	/* not mangled name */
-	      return NULL;
-	    }
-	  *cp++ = ')';
-	  *cp++ = ' ';		/* Overwriting 1st char of method name...  */
-	  strcpy(cp, mangled + (cp - demangled));	/* Get it back.  */
-	}
-
-      while (*cp && *cp == '_')
-	cp++;			/* Skip any initial underbars in
-				   method name.  */
-
-      for (; *cp; cp++)
-	if (*cp == '_')
-	  *cp = ':';		/* Replace remaining '_' with ':'.  */
-
-      *cp++ = ']';		/* closing right brace */
-      *cp++ = 0;		/* string terminator */
-      return demangled;
-    }
-  else
-    return NULL;	/* Not an objc mangled name.  */
-}
-
 /* Class representing the Objective-C language.  */
 
 class objc_language : public language_defn
@@ -320,16 +254,13 @@ public:
   bool sniff_from_mangled_name (const char *mangled,
 				char **demangled) const override
   {
-    *demangled = objc_demangle (mangled, 0);
+    *demangled = demangle_symbol (mangled, 0);
     return *demangled != NULL;
   }
 
   /* See language.h.  */
 
-  char *demangle_symbol (const char *mangled, int options) const override
-  {
-    return objc_demangle (mangled, options);
-  }
+  char *demangle_symbol (const char *mangled, int options) const override;
 
   /* See language.h.  */
 
@@ -385,6 +316,72 @@ public:
   { return macro_expansion_c; }
 };
 
+/* See declaration of objc_language::demangle_symbol above.  */
+
+char *
+objc_language::demangle_symbol (const char *mangled, int options) const
+{
+  char *demangled, *cp;
+
+  if (mangled[0] == '_'
+      && (mangled[1] == 'i' || mangled[1] == 'c')
+      && mangled[2] == '_')
+    {
+      cp = demangled = (char *) xmalloc (strlen (mangled) + 2);
+
+      if (mangled[1] == 'i')
+	*cp++ = '-';		/* for instance method */
+      else
+	*cp++ = '+';		/* for class    method */
+
+      *cp++ = '[';		/* opening left brace  */
+      strcpy(cp, mangled+3);	/* Tack on the rest of the mangled name.  */
+
+      while (*cp != '\0' && *cp == '_')
+	cp++;			/* Skip any initial underbars in class
+				   name.  */
+
+      cp = strchr(cp, '_');
+      if (cp == nullptr)	/* Find first non-initial underbar.  */
+	{
+	  xfree(demangled);	/* not mangled name */
+	  return nullptr;
+	}
+      if (cp[1] == '_')		/* Easy case: no category name.    */
+	{
+	  *cp++ = ' ';		/* Replace two '_' with one ' '.   */
+	  strcpy(cp, mangled + (cp - demangled) + 2);
+	}
+      else
+	{
+	  *cp++ = '(';		/* Less easy case: category name.  */
+	  cp = strchr(cp, '_');
+	  if (cp == nullptr)
+	    {
+	      xfree(demangled);	/* not mangled name */
+	      return nullptr;
+	    }
+	  *cp++ = ')';
+	  *cp++ = ' ';		/* Overwriting 1st char of method name...  */
+	  strcpy(cp, mangled + (cp - demangled));	/* Get it back.  */
+	}
+
+      while (*cp != '\0' && *cp == '_')
+	cp++;			/* Skip any initial underbars in
+				   method name.  */
+
+      for (; *cp != '\0'; cp++)
+	if (*cp == '_')
+	  *cp = ':';		/* Replace remaining '_' with ':'.  */
+
+      *cp++ = ']';		/* closing right brace */
+      *cp++ = 0;		/* string terminator */
+      return demangled;
+    }
+  else
+    return nullptr;	/* Not an objc mangled name.  */
+}
+
 /* Single instance of the class representing the Objective-C language.  */
 
 static objc_language objc_language_defn;