On 2017-06-03 05:11 +0300, Dmitriy Demin wrote:
> Hi,
>
> GCC emits strange ODR warning for the code below when I compile it
> with "-flto -fno-semantic-interposition -fPIC".
>
> ---- 1.h ----
> struct Foo {
> virtual ~Foo();
> };
>
> ---- 1.cpp ----
> #include "1.h"
>
> Foo::~Foo() { }
>
> ---- 2.cpp ----
> #include "1.h"
>
> void f(Foo x) {
> Foo y(x);
> }
>
> int main() { }
>
> --------
>
> When compiling it
> $ g++ -c 1.cpp -flto -fno-semantic-interposition -fPIC
> $ g++ -c 2.cpp -flto -fno-semantic-interposition -fPIC
> $ g++ 1.o 2.o
>
> it produces warnings:
>
> 1.h:1:8: warning: virtual table of type ‘struct Foo’ violates one
> definition rule [-Wodr]
> struct Foo {
> ^
> 1.h:1:8: note: the conflicting type defined in another translation unit
> struct Foo {
> ^
> 1.cpp:3:1: note: virtual method ‘__base_dtor ’
> Foo::~Foo() { }
> ^
> 1.h:2:13: note: ought to match virtual method ‘__comp_dtor ’ but does not
> virtual ~Foo();
>
> ---- ----
>
> I can't find anything wrong with the code, am I missing anything?
> Could it be a bug in ODR detection or optimizer? If so, should I worry
> about correctness of compiled code? I can only reproduce this when all
> three -f* flags are present. I tried current gcc snapshot (8.0.0
> 20170528) as well as gcc 7.1 and gcc 6.3. All of them show the same
> warning.
>
> Thanks in advance
I can't reproduce it on x86_64-linux-gnu. What is your architecture?
--
Xi Ruoyao <ryxi@xxxxxxxxxxxxxxxxx>
School of Aerospace Science and Technology, Xidian University
