Bug 16724 – RandomCover.popFront is a no-op for the first call

I let the code speak for itself. import std.random; import std.range; import std.algorithm; void main () { auto range = iota(10); auto randy = range.randomCover; //randy.front // uncomment this and the assert works randy.popFront; assert(randy.array.length == range.length - 1); }

PR here: https://github.com/dlang/phobos/pull/4957

Commit pushed to master at https://github.com/dlang/phobos https://github.com/dlang/phobos/commit/7c2dc1ccbadfb337325485cd045255598d536aa4 Merge pull request #4957 from RazvanN7/Issue_16724 Fix Issue 16724 - RandomCover.popFront is a no-op for the first call

Commit pushed to stable at https://github.com/dlang/phobos https://github.com/dlang/phobos/commit/7c2dc1ccbadfb337325485cd045255598d536aa4 Merge pull request #4957 from RazvanN7/Issue_16724

Commit pushed to newCTFE at https://github.com/dlang/phobos https://github.com/dlang/phobos/commit/7c2dc1ccbadfb337325485cd045255598d536aa4 Merge pull request #4957 from RazvanN7/Issue_16724

Sorry to have missed this, but the fix is itself broken, because it strips out the lazy `front` of `randomCover`. First, random algorithms (like random cover) ideally need to have a truly lazy initial `front` value, otherwise you can run into trivial errors like: auto arr = [1, 2, 3, 4, 5]; auto cover = arr.randomCover; cover.writeln; // three 'different' covers cover.writeln; // but each of them with cover.writeln; // the same first value ... so the check on already-chosen elements in `front` wasn't there by accident (although it may have needed further work in how it was implemented). Second, I just tried running the above right now and got a never-ending stream of `5, 5, 5, 5, 5, ...` out of my computer before I killed it. So I'm not sure that this new randomCover is working right at all :-(