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List:       hpux-cxx-dev
Subject:    CXX-DEV: Feedback requested on making -AA as default for aCC/PA-RISC
From:       "S G Ganesh" <sgganesh () india ! hp ! com>
Date:       2005-04-07 9:48:19
Message-ID: 001e01c53b56$e9d231a0$b0614c0f () asiapacific ! hpqcorp ! net
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This mail is regarding the feasibility of making -AA as the default compilation
mode for aCC on PA-RISC.

aCC has -AP as default on PA-RISC, and it is preferable to have -AA as default
(-AA is already default on aCC/Itanium). It has been many years since -AA was
introduced, and programming in Standard C++ has become mainstream. Also, more
and
more users are using -AA now.

What is the impact to the users if -AA is made as default for aCC/PA-RISC?
	1) Those who are already compiling with -AA will not have any impact.
	2) Those who are compiling all of their code explicitly with -AP will
not have any impact.
	3) Those who are depending on default behavior (-AP), but limit their use
to C, or use C++ without STL, iostreams and strings will not have any impact.
	4) Those who are depending on default behavior (-AP), but use STL, iostreams
and strings will have impact. If the old binaries (compiled with -AP) are mixed
with
new binaries (compiled with -AA), they will face problems (like core dumps). If
the
user doesn't prefer to change his code, she can explicitly pass -AP option.

The advantages of making -AA as default are:
	1) Encourages the users to write code more conformant to the C++ Standard
	2) Encourages the third-party vendors to provide their applications/libraries
compiled with -AA
	3) Will ease the eventual migration to Itanium where -AA is the default.

The disadvantages are as follows:
      1) Might expose the users to binary incompatibility problems
	2) Might result in unexpected surprises to the uninformed users
	3) Might force code changes to make the code work in -AA mode (if they don't
prefer changing the code, they can still overcome the problem by passing -AP
explicitly).

The differences between -AA and -AP are documented well, so, we can point to
the place where the users can look for:

http://h21007.www2.hp.com/dspp/tech/tech_TechDocumentDetailPage_IDX/1,1701,5520,
00.html

Please provide your valuable feedback on making -AA as default for aCC on
PA-RISC since
this is a significant change. If making -AA as default in the next release
(A.03.65 -
September, 2005) is too soon, it can be made with HP-UX release B.11.31 (next
year)?

Please mail your responses directly to cxx-feedback@india.hp.com, instead of
replying to
this mail in this group.

Thanks,
-Ganesh
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