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#!./perl
BEGIN {
chdir 't';
@INC = '../lib';
require './test.pl';
}
use strict;
use warnings;
plan (13);
# Historically constant folding was performed by evaluating the ops, and if
# they threw an exception compilation failed. This was seen as buggy, because
# even illegal constants in unreachable code would cause failure. So now
# illegal expressions are reported at runtime, if the expression is reached,
# making constant folding consistent with many other languages, and purely an
# optimisation rather than a behaviour change.
my $a;
$a = eval '$b = 0/0 if 0; 3';
is ($a, 3);
is ($@, "");
my $b = 0;
$a = eval 'if ($b) {return sqrt -3} 3';
is ($a, 3);
is ($@, "");
$a = eval q{
$b = eval q{if ($b) {return log 0} 4};
is ($b, 4);
is ($@, "");
5;
};
is ($a, 5);
is ($@, "");
# warn and die hooks should be disabled during constant folding
{
my $c = 0;
local $SIG{__WARN__} = sub { $c++ };
local $SIG{__DIE__} = sub { $c+= 2 };
eval q{
is($c, 0, "premature warn/die: $c");
my $x = "a"+5;
is($c, 1, "missing warn hook");
is($x, 5, "a+5");
$c = 0;
$x = 1/0;
};
like ($@, qr/division/, "eval caught division");
is($c, 2, "missing die hook");
}
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