What is C in practice? (Cerberus survey)

[Peter Sewell]

Dear X developers,

We're trying to explore, with a short survey, some aspects of what C
is in current mainstream practice: the behaviour that programmers
assume they can rely on, the behaviour provided by mainstream
compilers such as GCC, Clang, ICC, and MSVC, and the idioms used in
existing code, especially systems code.  These often differ in
important ways, from each other and from the ISO standard.

We're *not* asking what the standard permits (it's often more
restrictive and sometimes just unclear), or about obsolete hardware or
compilers.  And if you can point to examples (e.g. of real code that
depends on the feature in question) that would be great.

If you have a few minutes, the survey is here:

  https://goo.gl/PsgWuA

Don't forget to click "SUBMIT" when you're done.

Many thanks - the Cerberus team (www.cl.cam.ac.uk/~pes20/cerberus).