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Bug 1308822 - g++ <string> defines BIG_ENDIAN
g++ <string> defines BIG_ENDIAN
Product: Red Hat Enterprise Linux 7
Classification: Red Hat
Component: gcc (Show other bugs)
All Linux
unspecified Severity low
: rc
: ---
Assigned To: Jakub Jelinek
Depends On:
  Show dependency treegraph
Reported: 2016-02-16 03:39 EST by Anders Munch
Modified: 2016-02-16 03:52 EST (History)
3 users (show)

See Also:
Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of:
Last Closed: 2016-02-16 03:52:07 EST
Type: Bug
Regression: ---
Mount Type: ---
Documentation: ---
Verified Versions:
Category: ---
oVirt Team: ---
RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: ---

Attachments (Terms of Use)
Reproducing example. (58 bytes, text/x-csrc)
2016-02-16 03:39 EST, Anders Munch
no flags Details

External Trackers
Tracker ID Priority Status Summary Last Updated
CentOS 0010377 None None None 2016-02-16 03:39 EST

  None (edit)
Description Anders Munch 2016-02-16 03:39:20 EST
Created attachment 1127526 [details]
Reproducing example.

Description of problem:
System headers define the identifier BIG_ENDIAN in a program that does not include any platform-specific headers, thus changing the meaning of a program that checks this particular symbol. Since BIG_ENDIAN is not a symbol reserved for the implementation, this is a standards violation.

Version-Release number of selected component (if applicable):
CentOS 7.2.1511

How reproducible:

Steps to Reproduce:
1. g++ -c big_endian_predefined.cpp

Actual results:
#error message

Expected results:
Successful compilation.

Additional info:
It looks like BIG_ENDIAN and other symbols like it become defined when __USE_BSD is defined.
Comment 2 Jakub Jelinek 2016-02-16 03:52:07 EST
The C++ compiler indeed predefines _GNU_SOURCE macro, because libstdc++ headers need various functions from that namespace.  This is a known bug, but is not going to be fixed at least until GCC 7, and requires some heavy coordination between glibc and gcc.
See e.g.
Even after this is fixed upstream, this is not backportable to the RHEL 7 compiler and glibc.

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