[Bug c++/59475] gcc with flag -O1 fails to find template specialization when there is default one.
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59475
--- Comment #5 from Akela1101 akela1101 at gmail dot com ---
I see...
So, at -O1 in main.o the function is inline, and in A.o it has outer
implementation. At -O0 in both TU, not inline function is using.
The thing was not template specialization, but processing inline functions.
Sorry, I didn't know linker even had no warnings like multiple definition for
inline functions, e.g.:
TU 1:
int foo() { return 1; }
TU 2:
inline int foo() { return 2; }
[Bug c++/59475] New: gcc with flag -O1 fails to find template specialization when there is default one.
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59475
Bug ID: 59475
Summary: gcc with flag -O1 fails to find template
specialization when there is default one.
Product: gcc
Version: 4.8.2
Status: UNCONFIRMED
Severity: major
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: akela1101 at gmail dot com
Different behaviour with -O1 and without.
In first case g++ doesn't see template instantiation in .cpp and uses default.
In second case it uses .cpp even without function declaration.
Tested on x86 gcc-4.8.2 and x64 gcc-4.7.2.
Example:
=== A.h ===
#ifndef A_H
#define A_H
templatetypename T
int foo(T) { return 10; }
struct A
{
int x;
};
//template
//int foo(A t);
#endif // A_H
=== A.cpp ===
#include A.h
template
int foo(A t) { return t.x; }
=== main.cpp ===
#include A.h
int main()
{
A a;
a.x = 5;
int b = 10;
if( foo(a) == foo(b) ) return 1;
return 0;
}
===
Run script from attachment. Output must be:
$ ./run.sh
Without flags
0
With -O1
1
[Bug c++/59475] gcc with flag -O1 fails to find template specialization when there is default one.
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59475 --- Comment #1 from Akela1101 akela1101 at gmail dot com --- Created attachment 31421 -- http://gcc.gnu.org/bugzilla/attachment.cgi?id=31421action=edit ii, source, sh script
[Bug c++/59475] gcc with flag -O1 fails to find template specialization when there is default one.
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59475 --- Comment #3 from Akela1101 akela1101 at gmail dot com --- Thank you. But could you explain in more detail, why results of this little program are different depending on -O1 flag? I thought they both should be 0. Or am I wrong?
