=head2 Backward Compatibility
-If you are used with working with a version of Perl prior to the
+If you are used to working with a version of Perl prior to the
introduction of lexically scoped warnings, or have code that uses both
lexical warnings and C<$^W>, this section will describe how they interact.
=item 1.
If none of the three command line flags (B<-w>, B<-W> or B<-X>) that
-control warnings is used and neither C<$^W> or the C<warnings> pragma
+control warnings is used and neither C<$^W> nor the C<warnings> pragma
are used, then default warnings will be enabled and optional warnings
disabled.
This means that legacy code that doesn't attempt to control the warnings
The current hierarchy is:
- all -+
- |
- +- closure
- |
- +- deprecated
- |
- +- exiting
- |
- +- glob
- |
- +- io -----------+
- | |
- | +- closed
- | |
- | +- exec
- | |
- | +- layer
- | |
- | +- newline
- | |
- | +- pipe
- | |
- | +- unopened
- |
- +- imprecision
- |
- +- misc
- |
- +- numeric
- |
- +- once
- |
- +- overflow
- |
- +- pack
- |
- +- portable
- |
- +- recursion
- |
- +- redefine
- |
- +- regexp
- |
- +- severe -------+
- | |
- | +- debugging
- | |
- | +- inplace
- | |
- | +- internal
- | |
- | +- malloc
- |
- +- signal
- |
- +- substr
- |
- +- syntax -------+
- | |
- | +- ambiguous
- | |
- | +- bareword
- | |
- | +- digit
- | |
- | +- illegalproto
- | |
- | +- parenthesis
- | |
- | +- precedence
- | |
- | +- printf
- | |
- | +- prototype
- | |
- | +- qw
- | |
- | +- reserved
- | |
- | +- semicolon
- |
- +- taint
- |
- +- threads
- |
- +- uninitialized
- |
- +- unpack
- |
- +- untie
- |
- +- utf8----------+
- | |
- | +- surrogate
- | |
- | +- non_unicode
- | |
- | +- nonchar
- |
- +- void
+ all -+
+ |
+ +- closure
+ |
+ +- deprecated
+ |
+ +- exiting
+ |
+ +- experimental --+
+ | |
+ | +- experimental::lexical_subs
+ |
+ +- glob
+ |
+ +- imprecision
+ |
+ +- io ------------+
+ | |
+ | +- closed
+ | |
+ | +- exec
+ | |
+ | +- layer
+ | |
+ | +- newline
+ | |
+ | +- pipe
+ | |
+ | +- unopened
+ |
+ +- misc
+ |
+ +- numeric
+ |
+ +- once
+ |
+ +- overflow
+ |
+ +- pack
+ |
+ +- portable
+ |
+ +- recursion
+ |
+ +- redefine
+ |
+ +- regexp
+ |
+ +- severe --------+
+ | |
+ | +- debugging
+ | |
+ | +- inplace
+ | |
+ | +- internal
+ | |
+ | +- malloc
+ |
+ +- signal
+ |
+ +- substr
+ |
+ +- syntax --------+
+ | |
+ | +- ambiguous
+ | |
+ | +- bareword
+ | |
+ | +- digit
+ | |
+ | +- illegalproto
+ | |
+ | +- parenthesis
+ | |
+ | +- precedence
+ | |
+ | +- printf
+ | |
+ | +- prototype
+ | |
+ | +- qw
+ | |
+ | +- reserved
+ | |
+ | +- semicolon
+ |
+ +- taint
+ |
+ +- threads
+ |
+ +- uninitialized
+ |
+ +- unpack
+ |
+ +- untie
+ |
+ +- utf8 ----------+
+ | |
+ | +- non_unicode
+ | |
+ | +- nonchar
+ | |
+ | +- surrogate
+ |
+ +- void
Just like the "strict" pragma any of these categories can be combined
sub-category of the "syntax" category. It is now a top-level category
in its own right.
-
=head2 Fatal Warnings
X<warning, fatal>