C++ builds fail with modern C++ compilers #21073
Description
Module: Compress::Raw::Bzip2
Other modules may also be a problem.
Description
With a modern C++ compiler supporting and defaulting to C++ 17, the register storage class modifier is no longer supported, which causes the build to fail:
c++ -DNO_MATHOMS -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -Wall -Werror=pointer-arith -Werror=vla -Wextra -Wno-long-long -Wno-declaration-after-statement -Wc++-compat -Wwrite-strings -O2 -DVERSION=\"2.204\" -DXS_VERSION=\"2.204\" -fPIC "-I../.." -DBZ_NO_STDIO compress.c
compress.c:190:13: error: ISO C++17 does not allow 'register' storage class specifier [-Wregister]
register UChar rtmp;
^~~~~~~~~
Note that at least one C99 construct we use isn't valid in C++:
In file included from globals.c:25:
In file included from ./perl.h:6191:
./opcode.h:1004:2: warning: array designators are a C99 extension [-Wc99-designator]
[OP_NULL] = Perl_pp_null,
^~~~~~~~~
(designated struct initialization is supported in C++20 but not arrays)
Steps to Reproduce
# requires clang-16, installed here from the llvm deb archive
./Configure -des -Dusedevel -Dcc=clang++-16 -Accflags='-g -fno-omit-frame-pointer -fsanitize=address -fno-common -x c++' -Aldflags=-fsanitize=address -Accflags=-DNO_MATHOMS && make
Expected behavior
Successful build.
Workaround
Build with -std=c++11, which changes the message to a warning:
clang++-16 -c -I./zlib-src -g -fno-omit-frame-pointer -fsanitize=address -fno-common -x c++ -std=c++11 -DNO_MATHOMS -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -Wall -Werror=pointer-arith -Werror=vla -Wextra -Wno-long-long -Wno-declaration-after-statement -Wc++-compat -Wwrite-strings -O2 -DVERSION=\"2.204\" -DXS_VERSION=\"2.204\" -fPIC "-I../.." -DNO_VIZ -DZ_SOLO -DZ_PREFIX -DGZIP_OS_CODE=3 -DPerl_crz_BUILD_ZLIB=1 deflate.c
deflate.c:1282:5: warning: 'register' storage class specifier is deprecated and incompatible with C++17 [-Wdeprecated-register]
register Bytef *scan = s->window + s->strstart; /* current string */
^~~~~~~~~
Perl configuration
# from miniperl
Summary of my perl5 (revision 5 version 37 subversion 12) configuration:
Commit id: 6bbe21a508a82ef4a3849bd69a435b3cf8d5bf40
Platform:
osname=linux
osvers=5.10.0-21-amd64
archname=x86_64-linux
uname='linux venus 5.10.0-21-amd64 #1 smp debian 5.10.162-1 (2023-01-21) x86_64 gnulinux '
config_args='-des -Dusedevel -Dcc=clang++-16 -Accflags=-g -fno-omit-frame-pointer -fsanitize=address -fno-common -x c++ -Aldflags=-fsanitize=address -Accflags=-DNO_MATHOMS'
hint=recommended
useposix=true
d_sigaction=define
useithreads=undef
usemultiplicity=undef
use64bitint=define
use64bitall=define
uselongdouble=undef
usemymalloc=n
default_inc_excludes_dot=define
Compiler:
cc='clang++-16'
ccflags ='-g -fno-omit-frame-pointer -fsanitize=address -fno-common -x c++ -DNO_MATHOMS -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64'
optimize='-O2'
cppflags='-g -fno-omit-frame-pointer -fsanitize=address -fno-common -x c++ -DNO_MATHOMS -I/usr/local/include'
ccversion=''
gccversion='Debian Clang 16.0.3 (++20230502062952+da3cd333bea5-1~exp1~20230502183046.82)'
gccosandvers=''
intsize=4
longsize=8
ptrsize=8
doublesize=8
byteorder=12345678
doublekind=3
d_longlong=define
longlongsize=8
d_longdbl=define
longdblsize=16
longdblkind=3
ivtype='long'
ivsize=8
nvtype='double'
nvsize=8
Off_t='off_t'
lseeksize=8
alignbytes=8
prototype=define
Linker and Libraries:
ld='clang++-16'
ldflags =' -fsanitize=address -L/usr/local/lib'
libpth=/usr/lib/llvm-16/lib/clang/16/lib /usr/local/lib /usr/lib/x86_64-linux-gnu /usr/lib /usr/lib64
libs=-lpthread -lgdbm -ldl -lm -lcrypt -lutil -lc -lgdbm_compat
perllibs=-lpthread -ldl -lm -lcrypt -lutil -lc
libc=libc-2.31.so
so=so
useshrplib=false
libperl=libperl.a
gnulibc_version='2.31'
Dynamic Linking:
dlsrc=dl_dlopen.xs
dlext=so
d_dlsymun=undef
ccdlflags='-Wl,-E'
cccdlflags='-fPIC'
lddlflags='-shared -O2 -L/usr/local/lib'
Characteristics of this binary (from libperl):
Compile-time options:
HAS_LONG_DOUBLE
HAS_STRTOLD
HAS_TIMES
NO_MATHOMS
PERLIO_LAYERS
PERL_COPY_ON_WRITE
PERL_DONT_CREATE_GVSV
PERL_EXTERNAL_GLOB
PERL_HASH_FUNC_SIPHASH13
PERL_HASH_USE_SBOX32
PERL_IS_MINIPERL
PERL_MALLOC_WRAP
PERL_OP_PARENT
PERL_PRESERVE_IVUV
PERL_USE_DEVEL
PERL_USE_SAFE_PUTENV
USE_64_BIT_ALL
USE_64_BIT_INT
USE_LARGE_FILES
USE_LOCALE
USE_LOCALE_COLLATE
USE_LOCALE_CTYPE
USE_LOCALE_NUMERIC
USE_LOCALE_TIME
USE_PERLIO
USE_PERL_ATOF
USE_SITECUSTOMIZE
Built under linux
Compiled at May 4 2023 10:48:51
%ENV:
PERLBREW_BASHRC_VERSION="0.43"
PERLBREW_HOME="/home/tony/.perlbrew"
PERLBREW_MANPATH=""
PERLBREW_PATH="/home/tony/perl5/perlbrew/bin"
PERLBREW_ROOT="/home/tony/perl5/perlbrew"
PERLBREW_VERSION="0.67"
@INC:
/home/tony/dev/perl/git/perl6/cpan/AutoLoader/lib
/home/tony/dev/perl/git/perl6/dist/Carp/lib
/home/tony/dev/perl/git/perl6/dist/PathTools
/home/tony/dev/perl/git/perl6/dist/PathTools/lib
/home/tony/dev/perl/git/perl6/cpan/ExtUtils-Install/lib
/home/tony/dev/perl/git/perl6/cpan/ExtUtils-MakeMaker/lib
/home/tony/dev/perl/git/perl6/cpan/ExtUtils-Manifest/lib
/home/tony/dev/perl/git/perl6/cpan/File-Path/lib
/home/tony/dev/perl/git/perl6/ext/re
/home/tony/dev/perl/git/perl6/dist/Term-ReadLine/lib
/home/tony/dev/perl/git/perl6/dist/Exporter/lib
/home/tony/dev/perl/git/perl6/ext/File-Find/lib
/home/tony/dev/perl/git/perl6/cpan/Text-Tabs/lib
/home/tony/dev/perl/git/perl6/dist/constant/lib
/home/tony/dev/perl/git/perl6/cpan/version/lib
/home/tony/dev/perl/git/perl6/cpan/Getopt-Long/lib
/home/tony/dev/perl/git/perl6/cpan/Text-ParseWords/lib
/home/tony/dev/perl/git/perl6/cpan/ExtUtils-PL2Bat/lib
/home/tony/dev/perl/git/perl6/lib