PR# 19436 Infinite loop in routine {UTF_CONVERTER}.is_valid_utf_16

if argument `s' for `is_valid_utf_16' consists of a single code with value < 0xD800 then the for loop will never terminate.

I checked the lastest github version and it hasn't been fixed.

Fixed in rev#101649 of EiffelStudio 18.05 intermediate release.

As a temporary solution you can copy the following implementation of the feature and recompile the all the precompiles and projects from scratch:

	is_valid_utf_16 (s: SPECIAL [NATURAL_16]): BOOLEAN
			-- Is `s' a valid UTF-16 Unicode sequence?
		local
			i, n: INTEGER
			c: NATURAL_16
		do
			from
				i := 0
				n := s.count
				Result := True
			until
				i >= n or not Result
			loop
				c := s.item (i)
				if c < 0xD800 or c >= 0xE000 then
						-- Codepoint from Basic Multilingual Plane: one 16-bit code unit, this is valid Unicode.
				elseif c <= 0xDBFF then
					i := i + 1
					if i < n then
						c := s.item (i)
						Result := 0xDC00 <= c and c <= 0xDFF
					else
							-- Surrogate pair is incomplete, clearly not a valid UTF-16 sequence.
						Result := False
					end
				else
						-- Invalid starting surrogate pair which should be between 0xD800 and 0xDBFF.
					Result := False
				end
				i := i + 1

....
Output truncated, Click download to get the full message

Added an example test#utf003.

Also the loop termination condition is wrong:

until
   i > n or not Result

It should be

until
   i >= n or not Result

since
   s [n]
is out of bounds