sys_core_fold: Prevent case expressions from being evaluated twice

In e12b7d5331c58b41db06cadfa4af75b78b62a2b1, a bug was introduced
that would cause case expressions to be evaluated more than once
if there were aliases in the pattern. Example:

   X = Y = io:put_chars("some chars"),
   {X,Y}

That would be rewritten to code similar to (but in Core Erlang):

   X = io:put_chars("some chars"),
   X = io:put_chars("some chars"),
   {X,Y}

Make sure that we only evalute the expression once by doing a
transformation similar to (but in Core Erlang):

   NewVar = io:put_chars("some chars"),
   X = NewVar,
   Y = NewVar,
   {X,Y}

Reported-by: José Valim
Reported-by: Anthony Ramine

0 files changed, 0 insertions, 0 deletions