possible miscompilation on macOS Catalina 10.15.6

Paul Koning paulkoning at comcast.net
Thu Oct 29 16:17:57 UTC 2020

> On Oct 29, 2020, at 11:17 AM, Niels Möller <nisse at lysator.liu.se> wrote:
> tg at gmplib.org (Torbjörn Granlund) writes:
>> Trevor Spiteri <tspiteri at ieee.org> writes:
>>  This is all the information I got; sorry if it is incomplete. (The
>>  user's issue was solved by using their already installed homebrew?
>>  libraries instead of compiling GMP anew.)
>> OK, so *some* compiler compiled GMP with and *some* GMP test program
>> reported a segfault.  I will right away start the natural deduction over
>> all possible instances of compilers and GMP test cases. Oh wait, I need
>> to consider all possible CPUs and relevant environment variables as
>> well.
> And to be a bit less sarcastic: Fairly recent Apple compilers have had
> bugs making them miscompile GMP. Most likely explanation for the
> reported problem is that your user has a buggy version of the compiler
> installed. So try a different compiler. And if you suspect it's a
> genuine GMP bug, please follow bug reporting instructions in the fine
> manual.

There is another possibility: GMP might be doing something undefined, where previous compilers did "what we want" while some recent new ones do something different.  It isn't miscompilation if the source statement is undefined.


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