setup_sigwarn: explain why "warnings" aren't fatal (though "warn" is)

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>

1 files changed, 11 insertions, 0 deletions

diff --git a/Debian/Dgit.pm b/Debian/Dgit.pm
index 8ad3e3d..2c76263 100644
--- a/Debian/Dgit.pm
+++ b/Debian/Dgit.pm
@@ -159,6 +159,17 @@ sub forkcheck_mainprocess () {
 }
 
 sub setup_sigwarn () {
+    # $SIG{__WARN__} affects `warn` but not `-w` (`use warnings`).
+    # Ideally we would fatalise all warnings.  However:
+    #  1. warnings(3perl) has a long discussion of why this is
+    #     a bad idea due to bugs in, well, everything.
+    #  2. So maybe we would want to do that only when running the tests,
+    #  3. However, because it's a lexical keyword it's difficult to
+    #     manipulate at runtime.  We could use the caller's ^H
+    #     via caller, but that would take effect only in the main
+    #     program (which calls setup_sigwarn, eg dgit.git/dgit),
+    #     and not in the modules.
+    # This is all swimming too much upstream.
     forkcheck_setup();
     $SIG{__WARN__} = sub { 
 	confess $_[0] if forkcheck_mainprocess;