import GCC 6.4.0. see this url for details which are too large to
include here:

http://gcc.gnu.org/gcc-6/changes.html

the main visible changes appear to be:

- The default mode for C++ is now -

import GCC 6.4.0. see this url for details which are too large to
include here:

http://gcc.gnu.org/gcc-6/changes.html

the main visible changes appear to be:

- The default mode for C++ is now -std=gnu++14 instead of -std=gnu++98.
- The C and C++ compilers now support attributes on enumerators.
- Diagnostics can now contain "fix-it hints"
- more warnings (some added to -Wall)

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import GCC 5.3.0. see these urls for details which are too large to
include here:

http://gcc.gnu.org/gcc-4.9/changes.html
http://gcc.gnu.org/gcc-5/changes.html

(note that GCC 5.x is a release st

import GCC 5.3.0. see these urls for details which are too large to
include here:

http://gcc.gnu.org/gcc-4.9/changes.html
http://gcc.gnu.org/gcc-5/changes.html

(note that GCC 5.x is a release stream like GCC 4.9.x, 4.8.x, etc.)


the main issues we will have are:

The default mode for C is now -std=gnu11 instead of -std=gnu89.

ARM:
The deprecated option -mwords-little-endian has been removed.
The options -mapcs, -mapcs-frame, -mtpcs-frame and -mtpcs-leaf-frame
which are only applicable to the old ABI have been deprecated.

MIPS:
The o32 ABI has been modified and extended. The o32 64-bit
floating-point register support is now obsolete and has been removed.
It has been replaced by three ABI extensions FPXX, FP64A, and FP64.
The meaning of the -mfp64 command-line option has changed. It is now
used to enable the FP64A and FP64 ABI extensions.

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