When a static const reference bound is bound to a temporary, the temporary is
destroyed when the enclosing function exits. The lifetime of the temporary
should (I believe) be the same as that of the reference.
The program below illustrates the problem. The bug did not occur with 3.2.1,
3.2.3 or 3.3. It occurs with 3.3.1, 3.3.5, 3.4.1, 3.4.3 and a cvs checkout of
gcc-4_0-branch.
Command line and output:
--------------------------------------
$ g++ -v -save-temps lifetime.cpp
Reading specs from /usr/local/gcc-3.4.3/lib/gcc/i686-pc-linux-gnu/3.4.3/specs
Configured with: ../gcc-3.4.3/configure --exec-prefix=/usr/local/gcc-3.4.3
--prefix=/usr/local/gcc-3.4.3 --enable-threads --enable-languages=c,c++
Thread model: posix
gcc version 3.4.3
/usr/local/gcc-3.4.3/libexec/gcc/i686-pc-linux-gnu/3.4.3/cc1plus -E -quiet -v
-D_GNU_SOURCE lifetime.cpp -mtune=pentiumpro -o lifetime.ii
ignoring nonexistent directory
"/usr/local/gcc-3.4.3/lib/gcc/i686-pc-linux-gnu/3.4.3/../../../../i686-pc-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
/usr/local/gcc-3.4.3/lib/gcc/i686-pc-linux-gnu/3.4.3/../../../../include/c++/3.4.3
/usr/local/gcc-3.4.3/lib/gcc/i686-pc-linux-gnu/3.4.3/../../../../include/c++/3.4.3/i686-pc-linux-gnu
/usr/local/gcc-3.4.3/lib/gcc/i686-pc-linux-gnu/3.4.3/../../../../include/c++/3.4.3/backward
/usr/local/include
/usr/local/gcc-3.4.3/include
/usr/local/gcc-3.4.3/lib/gcc/i686-pc-linux-gnu/3.4.3/include
/usr/include
End of search list.
/usr/local/gcc-3.4.3/libexec/gcc/i686-pc-linux-gnu/3.4.3/cc1plus -fpreprocessed
lifetime.ii -quiet -dumpbase lifetime.cpp -mtune=pentiumpro -auxbase lifetime
-version -o lifetime.s
GNU C++ version 3.4.3 (i686-pc-linux-gnu)
compiled by GNU C version 3.4.3.
GGC heuristics: --param ggc-min-expand=47 --param ggc-min-heapsize=32080
as -V -Qy -o lifetime.o lifetime.s
GNU assembler version 2.11.93.0.2 (i386-redhat-linux) using BFD version
2.11.93.0.2 20020207
/usr/local/gcc-3.4.3/libexec/gcc/i686-pc-linux-gnu/3.4.3/collect2
--eh-frame-hdr -m elf_i386 -dynamic-linker /lib/ld-linux.so.2 /usr/lib/crt1.o
/usr/lib/crti.o /usr/local/gcc-3.4.3/lib/gcc/i686-pc-linux-gnu/3.4.3/crtbegin.o
-L/usr/local/gcc-3.4.3/lib/gcc/i686-pc-linux-gnu/3.4.3
-L/usr/local/gcc-3.4.3/lib/gcc/i686-pc-linux-gnu/3.4.3/../../.. lifetime.o
-lstdc++ -lm -lgcc_s -lgcc -lc -lgcc_s -lgcc
/usr/local/gcc-3.4.3/lib/gcc/i686-pc-linux-gnu/3.4.3/crtend.o /usr/lib/crtn.o
--------------------------------------
Preprocessed output:
--------------------------------------
# 1 "lifetime.cpp"
# 1 "<built-in>"
# 1 "<command line>"
# 1 "lifetime.cpp"
extern "C" int puts(const char*);
class Foo
{
public:
Foo() { puts("Foo()"); }
Foo(const Foo&) { puts("Foo(const Foo&)"); }
~Foo() { puts("~Foo()"); }
};
Foo get_foo()
{
return Foo();
}
void func()
{
static const Foo& t = get_foo();
}
int main()
{
puts("Before func call 1");
func();
puts("After func call 1");
puts("Before func call 2");
func();
puts("After func call 2");
return 0;
}
--------------------------------------
Program output:
--------------------------------------
Before func call 1
Foo()
~Foo()
After func call 1
Before func call 2
~Foo()
After func call 2
--------------------------------------
Expected program output (produced by intel C++ 7.0):
--------------------------------------
Before func call 1
Foo()
After func call 1
Before func call 2
After func call 2
~Foo()
--------------------------------------
--
Summary: Incorrect lifetime for temporary with static const
reference
Product: gcc
Version: 3.4.3
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: c++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: cmkyahoo-gccbugzilla at yahoo dot com
CC: gcc-bugs at gcc dot gnu dot org
GCC build triplet: i686-pc-linux-gnu
GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20416
