https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82414
Bug ID: 82414
Summary: Issue with ODR/LTO in G++
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: vasco.costa at gmail dot com
Target Milestone: ---
This code shows the abnormal behaviour:
---test.cc---
#include <stdio.h>
typedef __attribute__ ((__aligned__ (16))) struct _TEST_FLOAT128 {
__extension__ unsigned long long Part[2];
} TEST_FLOAT128;
int main( void )
{
TEST_FLOAT128 tf;
printf( "alignof(tf) = %d\n",(int)__alignof__(tf) );
printf( "alignof(struct _TEST_FLOAT128) = %d\n",(int)__alignof__(struct
_TEST_FLOAT128) );
printf( "alignof(TEST_FLOAT128) = %d\n",(int)__alignof__(TEST_FLOAT128) );
return 0;
}
---
$ g++-4.9 -O3 -flto -oalign test.cc -Wall -Wextra -g
# compiles without warnings.
$ g++-5 -O3 -flto -oalign test.cc -Wall -Wextra -g
test.cc:3:51: warning: type ‘struct _TEST_FLOAT128’ violates one definition
rule [-Wodr]
typedef __attribute__ ((__aligned__ (16))) struct _TEST_FLOAT128 {
^
test.cc:5:3: note: a type with different alignment is defined in another
translation unit
} TEST_FLOAT128;
^
# triggers a warning.
===
$ g++-5 -v
Using built-in specs.
COLLECT_GCC=g++-5
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/5/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu
5.4.0-6ubuntu1~16.04.4' --with-bugurl=file:///usr/share/doc/gcc-5/README.Bugs
--enable-languages=c,ada,c++,java,go,d,fortran,objc,obj-c++ --prefix=/usr
--program-suffix=-5 --enable-shared --enable-linker-build-id
--libexecdir=/usr/lib --without-included-gettext --enable-threads=posix
--libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu
--enable-libstdcxx-debug --enable-libstdcxx-time=yes
--with-default-libstdcxx-abi=new --enable-gnu-unique-object
--disable-vtable-verify --enable-libmpx --enable-plugin --with-system-zlib
--disable-browser-plugin --enable-java-awt=gtk --enable-gtk-cairo
--with-java-home=/usr/lib/jvm/java-1.5.0-gcj-5-amd64/jre --enable-java-home
--with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-5-amd64
--with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-5-amd64
--with-arch-directory=amd64 --with-ecj-jar=/usr/share/java/eclipse-ecj.jar
--enable-objc-gc --enable-multiarch --disable-werror --with-arch-32=i686
--with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib
--with-tune=generic --enable-checking=release --build=x86_64-linux-gnu
--host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 5.4.0 20160609 (Ubuntu 5.4.0-6ubuntu1~16.04.4)
===
This issue is also reported here:
https://bugs.launchpad.net/ubuntu/+source/gcc-5/+bug/1720959
https://sourceforge.net/p/mingw-w64/mailman/message/34950060/
Thanks for reading this message,
-vasc
