On Monday, 21 July 2014 at 21:10:43 UTC, Artur Skawina via
Digitalmars-d wrote:
On 07/21/14 21:53, via Digitalmars-d wrote:
On Monday, 21 July 2014 at 19:33:32 UTC, Artur Skawina via
Digitalmars-d wrote:
Disallowing integer overflow just at CT is not (sanely)
possible
in a language with D's CTFE capabilities. (Would result in
code
that compiles and works at runtime, but is not ctfe-able)
I'd like to see compile time _constants_ be unbounded rational
numbers with explicit truncation. It is when you assign it to
an in-memory location that you need to worry about bounds. The
same goes for calculations that doesn't do division.
No need to copy the bad parts of C.
Actually, C/C++ could get away with treating overflow during
constant
folding as an error (or at least emitting a warning) because of
the
lack of CTFE (and no templates in C's case). The code will
either
compile or it won't.
For D that is not possible -- if an expression is valid at
run-time
then it should be valid at compile-time
Why do you think that? There are many cases where that is not
true. Comparing pointers to two unrelated objects will work at
runtime, but causes an error in CTFE. You can read global
variables at runtime, not in CTFE. Etc.
The converse is true, though -- if it works at CTFE, it must work
at runtime.
Disallowing integer overflow in CTFE could certainly be
implemented. It's not a difficult experiment to run. It would be
interesting to see how many instances of overflow are bugs, and
how many are intentional.
