Issue 6378 - [emscripten] Make DependentString constexpr

compiled/String.h

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-present eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 122 matching lines @@
       return false;
 
     return std::memcmp(mBuf, other.mBuf, sizeof(value_type) * length()) == 0;
   }
 
   constexpr bool operator==(const String& other) const
   {
     return equals(other);
   }
 
-  bool operator!=(const String& other) const
+  constexpr bool operator!=(const String& other) const
   {
     return !equals(other);
   }
 
-  size_type find(value_type c, size_type pos = 0) const
+  constexpr size_type find(value_type c, size_type pos = 0) const
   {
     for (size_type i = pos; i < length(); ++i)
       if (mBuf[i] == c)
         return i;
     return npos;
   }
 
-  size_type find(const String& str, size_type pos = 0) const
+  constexpr size_type find(const String& str, size_type pos = 0) const
   {
     return find(str.mBuf, pos, str.length());
   }
 
-  size_type find(const value_type* str, size_type pos, size_type count) const
+  constexpr size_type find(const value_type* str, size_type pos, size_type count) const
   {
     if (pos > LENGTH_MASK || pos + count > length())
       return npos;
 
     if (!count)
       return pos;
 
     for (; pos + count <= length(); ++pos)
     {
       if (mBuf[pos] == str[0] &&
           std::memcmp(mBuf + pos, str, sizeof(value_type) * count) == 0)
       {
         return pos;
       }
     }
 
     return npos;
   }
 
-  size_type rfind(value_type c, size_type pos = npos) const
+  constexpr size_type rfind(value_type c, size_type pos = npos) const
   {
     if (length() == 0)
       return npos;
 
     if (pos >= length())
       pos = length() - 1;
 
     for (int i = pos; i >= 0; --i)
       if (mBuf[i] == c)
         return i;
@@ skipping 370 matching lines @@
   return OwnedString{value};
 }
 
 DependentString TrimSpaces(const String& value);
 
 // Splits the `value` string into two `DependentString`s excluding the character staying at `separatorPos`.
 // Useful for parsing.
 std::pair<DependentString, DependentString> SplitString(const String& value, String::size_type separatorPos);
 
 ABP_NS_END