Bug 16363 – Cannot construct a random access range using frontTransversal

The current implementation of FrontTransversal and Transversal both do not attempt to implement length or opDollar when the underlying range supports it, thus even when using assumeNotJagged the output range will not be a random access range. import std.range; void main() { int[][] darr = [[0, 1, 2], [4, 5, 6]]; auto fT = frontTransversal!(TransverseOptions.assumeNotJagged)(darr); auto l = fT.length; auto s = fT[0 .. $]; static assert(isRandomAccessRange!(typeof(fT))); } alex.d(5): Error: no property 'length' for type 'FrontTransversal!(int[][], cast(TransverseOptions)2)' alex.d(6): Error: undefined identifier '__dollar' alex.d(7): Error: static assert (isRandomAccessRange!(FrontTransversal!(int[][], cast(TransverseOptions)2))) is false

Commits pushed to master at https://github.com/dlang/phobos https://github.com/dlang/phobos/commit/b450113a4a6c5f6f329ef63cdaca4bd7ca3a8922 Enhancement 16363 Issue 16363 (Cannot construct a random access range using frontTransversal) https://issues.dlang.org/show_bug.cgi?id=16291 - Added the length property to frontTransversal (only if the length is known) https://github.com/dlang/phobos/commit/6394458fc3eed3800957d111650bd63bce010257 Merge pull request #4754 from togrue/issue_16363 Fix issue 16363 - Cannot construct a random access range using frontTransversal

Commits pushed to stable at https://github.com/dlang/phobos https://github.com/dlang/phobos/commit/b450113a4a6c5f6f329ef63cdaca4bd7ca3a8922 Enhancement 16363 https://github.com/dlang/phobos/commit/6394458fc3eed3800957d111650bd63bce010257 Merge pull request #4754 from togrue/issue_16363