perl – 为什么在调用foo()||时,标量返回值死？

我刚刚花了一大堆时间调试一个问题,我已经追溯到了wantarray().我已经将它解释为这个测试用例. (忽略在这种情况下$！不会有任何有用信息的事实).我想知道的是,为什么在第二个例子中,这些数组不会认为它在LIST上下文中被调用：

#!/usr/bin/env perl

use Strict;
use warnings;
use Test::More;

{
    my ( $one,$two ) = foo();
    is( $one,'a','just foo' );
    is( $two,'b','just foo' );
}

{
    my ( $one,$two ) = foo() || die $!;
    is( $one,'|| die' );
    is( $two,'|| die' );
}


done_tesTing();

sub foo {
    return wantarray ? ( 'a','b' ) : 'bar';
}

该测试的输出是：

$prove -v wantarray.pl
wantarray.pl ..
ok 1 - just foo
ok 2 - just foo
not ok 3 - || die
not ok 4 - || die
1..4

#   Failed test '|| die'
#   at wantarray.pl line 15.
#          got: 'bar'
#     expected: 'a'

#   Failed test '|| die'
#   at wantarray.pl line 16.
#          got: undef
#     expected: 'b'
# Looks like you failed 2 tests of 4.
Dubious,test returned 2 (wstat 512,0x200)
Failed 2/4 subtests

Test SumMary Report
-------------------
wantarray.pl (Wstat: 512 Tests: 4 Failed: 2)
  Failed tests:  3-4
    Non-zero exit status: 2
    Files=1,Tests=4,0 wallclock secs ( 0.03 usr  0.01 sys +  0.02 cusr  0.00 csys =  0.06 CPU)
    Result: FAIL