https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71968
Bug ID: 71968
Summary: Type with no linkage in signature: symbols for unique
entities link together
Product: gcc
Version: 7.0
Status: UNCONFIRMED
Keywords: wrong-code
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: hstong at ca dot ibm.com
Target Milestone: ---
GCC produces symbols for entities which cannot possibly be referenced from
another translation unit in such a way that distinct entities link together.
In the following program, the templates in question are neither equivalent nor
functionally equivalent.
Online compiler: http://melpon.org/wandbox/permlink/YXAMmVBat8N2aXRe
### SOURCE (a.cc):
extern "C" void abort();
void bar();
namespace {
struct A { A(int); char sizer[1]; };
}
template <typename T> void foo(char (*)[sizeof A(T(0))]) {
static unsigned cnt = 0;
if (cnt++) abort();
}
int main(void) { bar(); foo<int>(0); }
### SOURCE (b.cc):
extern "C" void abort();
namespace {
struct A { A(int); char sizer[2]; };
}
template <typename T> void foo(char (*)[sizeof A(T(0))]) {
static unsigned cnt = 0;
if (cnt++) abort();
}
void bar() { foo<int>(0); }
### COMMANDS:
g++ -c -o a.o -std=c++11 a.cc
g++ -c -o b.o -std=c++11 b.cc
g++ -o a.out a.o b.o
./a.out
### EXPECTED OUTPUT:
rc=0
### ACTUAL OUTPUT:
(aborts)
### COMPILER VERSION INFO (g++ -v):
Using built-in specs.
COLLECT_GCC=/usr/local/gcc-head/bin/g++
COLLECT_LTO_WRAPPER=/usr/local/gcc-head/libexec/gcc/x86_64-pc-linux-gnu/7.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: /home/heads/gcc/gcc-source/configure
--prefix=/usr/local/gcc-head --enable-languages=c,c++ --enable-lto
--disable-multilib --without-ppl --without-cloog-ppl --enable-checking=release
--disable-nls
Thread model: posix
gcc version 7.0.0 20160721 (experimental) (GCC)
