[perl #128540] "warnings" pragma silently ignores postfixed "FATAL"import parameter

# New Ticket Created by  Rob Dixon 
# Please include the string:  [perl #128540]
# in the subject line of all future correspondence about this issue. 
# <URL: https://rt.perl.org/Ticket/Display.html?id=128540 >


This is a bug report for perl from the.rob.dixon@gmail.com,
generated with the help of perlbug 1.40 running under perl 5.24.0.


-----------------------------------------------------------------

The documentation for the `warnings` pragma has this

*    The presence of the word "FATAL" in the category list will escalate*
*    warnings in those categories into fatal errors in that lexical scope.*

which works fine for the examples given, like

    use warnings FATAL => 'all'

This also works fine if the category is defaulted. For instance

    use warnings 'FATAL'

is equivalent to the previous example.

`FATAL` may be also used to separate fatal categories from non-fatal ones,
so that

    use warnings qw/ uninitialized FATAL deprecated experimental /

makes "deprecated" and "experimental" warnings fatal while "uninitialized"
warnings
are enabled but non-fatal

However the `FATAL` is silently ineffective if it is used without any
following
categories.

The doeumentation would have us believe that

    use warnings qw/ all FATAL /

should work fine, but the FATAL has no effect at all and gives no message
to say so.
This is identical to `use warnings`

I suggest that this should result in a compilation failure in the same way
as
"Unknown warnings category 'xx'". The documentation should also be
corrected to
explain that the position of `FATAL` within the import parameters is
significant

-----------------------------------------------------------------
---
Flags:
    category=core
    severity=medium
---
Site configuration information for perl 5.24.0:

Configured by strawberry-perl at Tue May 10 21:33:22 2016.

Summary of my perl5 (revision 5 version 24 subversion 0) configuration:

  Platform:
    osname=MSWin32, osvers=6.3, archname=MSWin32-x64-multi-thread
    uname='Win32 strawberry-perl 5.24.0.1 #1 Tue May 10 21:30:49 2016 x64'
    config_args='undef'
    hint=recommended, useposix=true, d_sigaction=undef
    useithreads=define, usemultiplicity=define
    use64bitint=define, use64bitall=undef, uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
  Compiler:
    cc='gcc', ccflags =' -s -O2 -DWIN32 -DWIN64 -DCONSERVATIVE
 -DPERL_TEXTMODE_SCRIPTS -DPERL_IMPLICIT_CONTEXT -DPERL_IMPLICIT_SYS
-fwrapv -fno-strict-aliasing -mms-bitfields',
    optimize='-s -O2',
    cppflags='-DWIN32'
    ccversion='', gccversion='4.9.2', gccosandvers=''
    intsize=4, longsize=4, ptrsize=8, doublesize=8, byteorder=12345678,
doublekind=3
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=16,
longdblkind=3
    ivtype='long long', ivsize=8, nvtype='double', nvsize=8, Off_t='long
long', lseeksize=8
    alignbytes=8, prototype=define
  Linker and Libraries:
    ld='g++', ldflags ='-s -L"C:\strawberry\perl\lib\CORE"
-L"C:\strawberry\c\lib"'
    libpth=C:\strawberry\c\lib C:\strawberry\c\x86_64-w64-mingw32\lib
C:\strawberry\c\lib\gcc\x86_64-w64-mingw32\4.9.2
    libs=-lmoldname -lkernel32 -luser32 -lgdi32 -lwinspool -lcomdlg32
-ladvapi32 -lshell32 -lole32 -loleaut32 -lnetapi32 -luuid -lws2_32 -lmpr
-lwinmm -lversion -lodbc32 -lodbccp32 -lcomctl32
    perllibs=-lmoldname -lkernel32 -luser32 -lgdi32 -lwinspool -lcomdlg32
-ladvapi32 -lshell32 -lole32 -loleaut32 -lnetapi32 -luuid -lws2_32 -lmpr
-lwinmm -lversion -lodbc32 -lodbccp32 -lcomctl32
    libc=, so=dll, useshrplib=true, libperl=libperl524.a
    gnulibc_version=''
  Dynamic Linking:
    dlsrc=dl_win32.xs, dlext=xs.dll, d_dlsymun=undef, ccdlflags=' '
    cccdlflags=' ', lddlflags='-mdll -s -L"C:\strawberry\perl\lib\CORE"
-L"C:\strawberry\c\lib"'


---
@INC for perl 5.24.0:
    C:/Strawberry/perl/site/lib/MSWin32-x64-multi-thread
    C:/Strawberry/perl/site/lib
    C:/Strawberry/perl/vendor/lib
    C:/Strawberry/perl/lib
    .

---
Environment for perl 5.24.0:
    HOME (unset)
    LANG (unset)
    LANGUAGE (unset)
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=C:\PHP\;C:\ProgramData\Oracle\Java\javapath;C:\Program Files
(x86)\NVIDIA
Corporation\PhysX\Common;C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\System32\Wbem;C:\WINDOWS\System32\WindowsPowerShell\v1.0\;C:\Strawberry\perl\bin;C:\Strawberry\perl\site\bin;C:\Strawberry\c\bin;C:\Python27\;C:\Python27\Scripts;E:\Perl\source\public;C:\ProgramData\chocolatey\bin;C:\Program
Files\Git\cmd;C:\ffmpeg\bin;C:\SQLite;C:\PHP;C:\tools\php
    PERL_BADLANG (unset)
    SHELL (unset)

• [perl #128540] "warnings" pragma silently ignores postfixed "FATAL"import parameter by Dan Collins via RT
• [perl #128540] "warnings" pragma silently ignores postfixed "FATAL"import parameter by Rob Dixon