Template constraints error messages using cputs()

[bearophile]

BCS:

> All the issues you address up to where you propose ctputs are bugs in DMD, 
> not pragma(msg,...) as for ctputs as a /replacement/ see my replay to the 
> bug.

Thank you for this answer and the answer in bugzilla. I explain the problems I find while I program in D, and sometimes I try to give a starting point for a solution, but usually it's not hard to find solutions better than the ones I suggest.

I have written an answer in Bugzilla, I don't know if it's enough.


> you will not convince me that what it currently does is less than /very useful/. 

You are right :-)


> My minimum requirements for a pragma(msgm...) replacement would be that it 
> take any expression that results in an immutable(char[]) and, at compile 
> time (and only compile time) during the semantic pass (while the code is 
> processed, not evaluated) output the string.

I'd like to ctputs() to act as std.c.stdio.puts() if the function is run at run time.

  
> The major cases where your ctputs fails on this are inside a function that 
> can be evaluated via CTFE:
> - If placed in a RT loop it could be evaluated to many times.
> - If placed in a code path that isn't hit via CTFE, it never outputs anything.
> - If the function gets run at RT, then you need to add a guard to prevent 
> it from generating output at RT.

This is by design.

But I understand your point, ctputs seems designed for a purpose different than pragma(msg), it doesn't seem a replacement. ctputs is meant as a way to print strings from function if you call the function both at runtime or compile time with CTFE. pragma(msg) is meant to show a message at compile time. So pragma(msg) needs to be debugged and then kept.

I probably have update the bug report, and I'd like to split it in a pragma(msg) bug report (essentially to make it test its input argument better), plus an enhancement request for a ctputs() probably in std.intrinsic :-)

Bye and thank you,
bearophile