Subject: bug#38748: 28.0.50; crash on MacOS 10.15.2

From: Robert Pluim <[email-masked]>
Date: Wed, 08 Jan 2020 23:23:48 +0100

>>>>> On Wed, 8 Jan 2020 22:18:11 +0000, Pip Cet <[email-masked]> said:

    Pip> On Wed, Jan 8, 2020 at 9:43 PM Robert Pluim <[email-masked]> wrote:
    >> gcc --version
    >> Configured with: --prefix=/Library/Developer/CommandLineTools/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
    >> Apple LLVM version 10.0.1 (clang-1001.0.46.4)
    >> Target: x86_64-apple-darwin18.7.0
    >> Thread model: posix
    >> InstalledDir: /Library/Developer/CommandLineTools/usr/bin
    >> 
    >> Iʼve attached the disassembly of the two versions. They're very very
    >> similar (this is with -g3 -O0).

    Pip> But wait, doesn't the bug happen in both unoptimized versions? I
    Pip> should have been clearer: my suspicion is the bug only goes away if
    Pip> tail calls are optimized, which happens only with optimizations
    Pip> enabled.

No, it only happens with the initialisation of 'ok', optimised or not.

As another data point, Iʼm writing this from an emacs with 'ok =
true', which has not crashed yet....

Robert