[erlang-bugs] A possibly-spurious warning message on 18.0-rc1 when enabling compile inline option

[Kenji Rikitake]

A warning message, which does not make sense, is generated when
compiling the following code on 18.0-rc1 (both on FreeBSD and OS X):

erlc -Werror buftest.erl
compile: warnings being treated as errors
buftest.erl:15: a term is constructed, but never used

This doesn't happen on 17.5,
and this message is not generated when
`-compile({inline, [loop/1]})` doesn't exist.

buftest.erl source code:

-module(buftest).

-export([
        loop/1
    ]).

-compile({inline, [loop/1]}).

calc(H, H2) ->
    ok = io:format("H = ~p, H2 = ~p~n", [H, H2]),
    H2.

loop({[H], RL}) ->
    NL = lists:reverse(RL),
    loop({[H|NL], []}); % <- this line generates the warning
loop({L, RL}) ->
    [H|L2] = L,
    [H2|L3] = L2,
    NH2 = calc(H, H2),
    NL2 = [NH2|L3],
    NRL = [H|RL],
    {NL2, NRL}.