Undoc'd Feature?

[jte]

(07-03-2022 01:03 PM)Wes Loewer Wrote:  ⋮
For instance, in C and its descendants,

Code:

a=5;
b=++a;

Now a and b are both 6. However,

Code:

a=5;
b=a++;

In C, a is again 6 but b is 5 since a is not incremented until after the right side is evaluated. In CAS, a and b are both 6. So a++ in CAS is like ++a in C.
⋮

— some good and insightful comments (some of which got snipped out, & into “⋮”)… Reading this thread made me think of posing a little C++ challenge. If one were to add a single character to the first line of the C++ code below, one would enter the land of undefined behaviour for versions of C++ before C++17:

Code:

int a = 0,b = a;

a=5;
b=++a;

a=5;
b=a++;

Years ago, I fixed some bugs of this sort in the Prime source code (likely back when it was the 39gII code base; if not then, just a bit later).