http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60783
Bug ID: 60783
Summary: unexpected address variation when taking address of
reference, const reference, etc.
Product: gcc
Version: 4.8.2
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: other
Assignee: unassigned at gcc dot gnu.org
Reporter: parke.nexus at gmail dot com
I am comparing passing pointers versus references into a function. I
encountered unexpected variations when taking the address of passed in
references.
Perhaps most notably, if
f is declared as: int* const & f
h is declared as: const int* const & h
then
& f is not equal to & h
Below is:
1) test code that reproduces the issue
2) output when compiled with g++ 4.8.2 on Ubuntu 14.04 on x68_64
3) output when compiled with g++ 4.7.3 on Ubuntu 13.04 on i686
I in the output, I expect "e" through "l" to be identical.
In 2, e f g and l are identical.
h to k are identical to each other, but different from e f g and l.
In 3, e f g and l are identical. h to k are each unique.
Here is code to reproduce the issue:
#include <stdio.h>
void foo_ab ( int* a, int & b ) {
printf ( "a %p\n", a );
printf ( "b %p\n", & b ); }
void foo_cd ( void** c, void* & d ) {
printf ( "c %p\n", c );
printf ( "d %p\n", & d ); }
void foo_ef ( int** e, int* const & f ) {
printf ( "e %p\n", e );
printf ( "f %p\n", & f ); }
void foo_gh ( int** g, const int* const & h ) {
printf ( "g %p\n", g );
printf ( "h %p\n", & h ); }
void foo_i ( const void* const & i ) { printf ( "i %p\n", & i ); }
void foo_j ( const int* const & j ) { printf ( "j %p\n", & j ); }
void foo_k ( void* const & k ) { printf ( "k %p\n", & k ); }
void foo_l ( int* const & l ) { printf ( "l %p\n", & l ); }
int main () {
int n = 5;
int* p = & n;
printf ( "\n" );
foo_ab ( & n, n );
// foo_cd ( & p, p ); // causes compile time error
printf ( "\n" );
foo_ef ( & p, p );
printf ( "\n" );
foo_gh ( & p, p );
printf ( "\n" );
foo_i ( p );
foo_i ( p );
printf ( "\n" );
foo_j ( p );
foo_j ( p );
printf ( "\n" );
foo_k ( p );
foo_k ( p );
printf ( "\n" );
foo_l ( p );
foo_l ( p );
return 0; }
----
$ ./a.out
a 0x7fff3a1e669c
b 0x7fff3a1e669c
e 0x7fff3a1e66a0
f 0x7fff3a1e66a0
g 0x7fff3a1e66a0
h 0x7fff3a1e66a8
i 0x7fff3a1e66a8
i 0x7fff3a1e66a8
j 0x7fff3a1e66a8
j 0x7fff3a1e66a8
k 0x7fff3a1e66a8
k 0x7fff3a1e66a8
l 0x7fff3a1e66a0
l 0x7fff3a1e66a0
$ g++ -v
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/4.8/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 4.8.2-19ubuntu1'
--with-bugurl=file:///usr/share/doc/gcc-4.8/README.Bugs
--enable-languages=c,c++,java,go,d,fortran,objc,obj-c++ --prefix=/usr
--program-suffix=-4.8 --enable-shared --enable-linker-build-id
--libexecdir=/usr/lib --without-included-gettext --enable-threads=posix
--with-gxx-include-dir=/usr/include/c++/4.8 --libdir=/usr/lib --enable-nls
--with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug
--enable-libstdcxx-time=yes --enable-gnu-unique-object --disable-libmudflap
--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-4.8-amd64/jre --enable-java-home
--with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-4.8-amd64
--with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-4.8-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 --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 4.8.2 (Ubuntu 4.8.2-19ubuntu1)
$ ./a.out
a 0xbfc74a3c
b 0xbfc74a3c
e 0xbfc74a40
f 0xbfc74a40
g 0xbfc74a40
h 0xbfc74a44
i 0xbfc74a48
i 0xbfc74a4c
j 0xbfc74a50
j 0xbfc74a54
k 0xbfc74a58
k 0xbfc74a5c
l 0xbfc74a40
l 0xbfc74a40
$ g++ -v
Using built-in specs.
COLLECT_GCC=/usr/bin/g++-4.7.real
COLLECT_LTO_WRAPPER=/usr/lib/gcc/i686-linux-gnu/4.7/lto-wrapper
Target: i686-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu/Linaro
4.7.3-1ubuntu1' --with-bugurl=file:///usr/share/doc/gcc-4.7/README.Bugs
--enable-languages=c,c++,go,fortran,objc,obj-c++ --prefix=/usr
--program-suffix=-4.7 --enable-shared --enable-linker-build-id
--libexecdir=/usr/lib --without-included-gettext --enable-threads=posix
--with-gxx-include-dir=/usr/include/c++/4.7 --libdir=/usr/lib --enable-nls
--with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug
--enable-libstdcxx-time=yes --enable-gnu-unique-object --enable-plugin
--with-system-zlib --enable-objc-gc --enable-targets=all --with-cloog
--enable-cloog-backend=ppl --disable-cloog-version-check
--disable-ppl-version-check --enable-multiarch --disable-werror
--with-arch-32=i686 --with-multilib-list=m32,m64,mx32 --with-tune=generic
--enable-checking=release --build=i686-linux-gnu --host=i686-linux-gnu
--target=i686-linux-gnu
Thread model: posix
gcc version 4.7.3 (Ubuntu/Linaro 4.7.3-1ubuntu1)
