beam_type: Eliminate crash

The following code:

simple() ->
    case try 0 after [] end of
	0 -> college;
	1 -> 0
    end.

would crash the compiler like this:

crash reason: {case_clause,
    {'EXIT',
        {function_clause,
            [{beam_type,simplify_select_val_int,
                 [{select,select_val,
                      {x,0},
                      {f,7},
                      [{integer,1},{f,9},{integer,0},{f,8}]},
                  0],
                 [{file,"beam_type.erl"},{line,169}]},
             {beam_type,simplify_basic_1,3,
                 [{file,"beam_type.erl"},{line,155}]},
             {beam_type,opt,3,[{file,"beam_type.erl"},{line,57}]},
             {beam_type,function,1,[{file,"beam_type.erl"},{line,36}]},
             {beam_type,'-module/2-lc$^0/1-0-',1,
                 [{file,"beam_type.erl"},{line,30}]},
             {beam_type,module,2,[{file,"beam_type.erl"},{line,30}]},
             {compile,'-select_passes/2-anonymous-2-',2,
                 [{file,"compile.erl"},{line,521}]},
             {compile,'-internal_comp/4-anonymous-1-',2,
                 [{file,"compile.erl"},{line,306}]}]}}}

The root cause is that the type representation is not well-defined.

Integers could be represented in three different ways:

  integer
  {integer,{1,10}}
  {integer,0}

However, only the first two forms were handled.

To avoid similar problems in the future:

* Make the type representation stricter. Make sure that integers are
  only represented as 'integer' or {integer,{Min,Max}}.

* Call verify_type/1 whenever a new type is added (not only when
  merging types) to ensure that only the supported types are added
  to the type database).

(ERL-150)

0 files changed, 0 insertions, 0 deletions