From @skids

A newly created Failure can be prevented from sinking by assigning
it to a variable. Binding it to a variable also protects it from
being immediately sunk. However, when the latter happens as the last
statement in an if { ... }, the exception is sunk and thrown.

Expected behavior​: The "bar" failure below should not throw.

$ cat /tmp/foo.pm6
sub a {
  if (1) {
  my $f = Failure.new("foo");
  }
  return 1;
}
my $a = a();

sub b {
  if (1) {
  my $f := Failure.new("bar");
  }
  return 1;
}
my $b = b();
42.say

$ perl6 /tmp/foo.pm6
bar
  in sub b at /tmp/foo.pm6​:10
  in block <unit> at /tmp/foo.pm6​:15

Actually thrown at​:
  in sub b at /tmp/foo.pm6​:10
  in block <unit> at /tmp/foo.pm6​:15

From @TimToady

Minimal test case​:

{ my $f := Failure.new("bar"); }

This doesn't seem to be sink related, at least not directly. It seems more to be related to the difference between storing things in a local vs in a lexical, and how those are treated on statement or return boundaries.

From @TimToady

Fixed in 091ee7507464595e7712f4ae911d95d467e5281b

Tests in 8b97aa4f6191affdd91da78607eca4ae6dc73b11

@TimToady - Status changed from 'new' to 'resolved'