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Re: ODR violation warning when compiling with -flto -fno-semantic-interposition -fPIC

From: Dmitriy Demin <demindf at gmail dot com>
To: gcc-help at gcc dot gnu dot org
Date: Sat, 3 Jun 2017 13:16:50 +0300
Subject: Re: ODR violation warning when compiling with -flto -fno-semantic-interposition -fPIC
Authentication-results: sourceware.org; auth=none
References: <CAO7G77f4TwfANV0+qZE2Qn8-k9hdV4saca7ytemmAUQVFvq2sg@mail.gmail.com> <1496465038.10850.2.camel@stu.xidian.edu.cn>

> I can't reproduce it on x86_64-linux-gnu.  What is your architecture?

Ups, I forgot to mention one more flag "-O" which is important here.

So building instructions should be like this with the same code:

$ g++ -c 1.cpp -O -flto -fno-semantic-interposition -fPIC
$ g++ -c 2.cpp -O -flto -fno-semantic-interposition -fPIC
$ g++ 1.o 2.o

I tried this on two PCs, both x86_64-linux-gnu (Ubuntu and NixOS), on
both of them it produces the warning.

I also just found out that it compiles fine on gcc5 (5.4.1 20160904).

References:
- ODR violation warning when compiling with -flto -fno-semantic-interposition -fPIC
  - From: Dmitriy Demin
- Re: ODR violation warning when compiling with -flto -fno-semantic-interposition -fPIC
  - From: Xi Ruoyao

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