Bug 4936 – Better error when type inference fails due to incorrect template parameter type

Basically two string[] fail to mach the completeSort signature. This worked with 2.048 import std.algorithm; void main() { auto foo = ["a the way home", "can I say"]; auto bar = ["be it here or there", "you may"]; completeSort(foo, bar); } test.d(7): Error: template std.algorithm.completeSort(alias less = "a < b",SwapStrategy ss = SwapStrategy.unstable,Range1,Range2) if (hasLength!(Range2) && hasSlicing!(Range2)) does not match any function template declaration test.d(7): Error: template std.algorithm.completeSort(alias less = "a < b",SwapStrategy ss = SwapStrategy.unstable,Range1,Range2) if (hasLength!(Range2) && hasSlicing!(Range2)) cannot deduce template function from argument types !()(string[],string[])

completeSort no longer takes arbitrary ranges, it takes a SortedRange as the first parameter, and that is causing the error. I guess the easiest would be to include the parameter list, but maybe that would make it too cluttered?

Looks like the example code doesn't actually work either. import std.algorithm; import std.range; void main() { int[] a = [ 1, 2, 3 ]; int[] b = [ 4, 0, 6, 5 ]; completeSort(assumeSorted(a), b); assert(a == [ 0, 1, 2 ]); assert(b == [ 3, 4, 5, 6 ]); }

Really? This has been broken since _049_ and no one has commented on it? Clearly, no one is using completeSort at all.

This works: --- import std.stdio, std.algorithm, std.range; void main() { auto foo = ["a the way home", "can I say"]; auto bar = ["be it here or there", "you may"]; completeSort(foo.assumeSorted, bar.assumeSorted); } --- https://run.dlang.io/is/aeO4fp > Clearly, no one is using completeSort at all Yeah if it's open for eight years, that's a very good sign no one uses it... I'm closing this as it's too old for an regression and assumeSorted works.

Seb, this is specifically about the error message poorly directing the user to provide a SortedRange. This was more confusing to me since I hit the issue after the library change, rather than when initially writing the code. As I don't know exact changes to improve the error message I'll leave it closed, but it is a larger issue using templates and type inference which could be improved.

Argh sorry - I was too busy working myself through old issues. Thanks for the reminder. -> REOPENED

Right now the error is: Error: none of the overloads of template `std.algorithm.sorting.completeSort` are callable using argument types `!()(string[], string[])` Candidate is: `completeSort(alias less = "a < b", SwapStrategy ss = SwapStrategy.unstable, Lhs, Rhs)(SortedRange!(Lhs, less) lhs, Rhs rhs)` So it is pointing the declaration and it can be observed that `foo` is not SortedRange.