Bug 8330 – std.algorithm.find doesn't handle reference type ranges correctly

This code import std.algorithm; import std.range; void main() { auto arr = [1, 2, 3, 4, 1, 9, 12, 42]; assert(find(arr, [9, 12, 42]) == [9, 12, 42]); auto range = refRange(&arr); assert(equal(*find(range, [9, 12, 42]).ptr, [9, 12, 42])); } fails, giving core.exception.AssertError@q(10): Assertion failure ---------------- ./q(_d_assertm+0x26) [0x43aa4e] ./q() [0x438826] ./q(_Dmain+0x1f8) [0x4312d8] ./q(extern (C) int rt.dmain2.main(int, char**).void runMain()+0x1c) [0x43b2e4] ./q(extern (C) int rt.dmain2.main(int, char**).void tryExec(scope void delegate())+0x2a) [0x43ac5e] ./q(extern (C) int rt.dmain2.main(int, char**).void runAll()+0x3b) [0x43b32b] ./q(extern (C) int rt.dmain2.main(int, char**).void tryExec(scope void delegate())+0x2a) [0x43ac5e] ./q(main+0xd1) [0x43abe9] /lib/libc.so.6(__libc_start_main+0xf5) [0x7fd9af788455] ---------------- If you print out the result of the find that fails, you get [12, 49]. I believe that the problem is with this particular overload of find: R1 find(alias pred = "a == b", R1, R2)(R1 haystack, R2 needle) if (isRandomAccessRange!R1 && hasLength!R1 && isBidirectionalRange!R2 && is(typeof(binaryFun!pred(haystack.front, needle.front)) : bool)) It appears that whenever you use a reference type haystack, and your needle has a length greater than 2, the result is missing one element on its front. It works with needles of lengthe 2 or less, and it works fine with value type ranges just fine but not reference types. And it also fails with import std.algorithm; import std.range; import std.stdio; class C { this(int[] arr) { _arr = arr; } bool empty() {return _arr.empty;} @property auto save() {return new C(_arr);} @property int front() {return _arr.front;} void popFront() {_arr.popFront();} @property int back() {return _arr.back;} void popBack() {_arr.popBack();} @property size_t length() {return _arr.length;} auto opIndex(size_t i) { return _arr[i]; } auto opSlice(size_t i, size_t j) { return new C(_arr[i .. j]); } auto opSlice() { return save; } int[] _arr; } static assert(isRandomAccessRange!C); void main() { auto arr = [1, 2, 3, 4, 1, 9, 12, 42]; auto c = new C(arr); auto range = refRange(&arr); assert(equal(find(c, [9, 12, 42]), [9, 12, 42])); } so it's not a bug in RefRange.

No longer occurs. Both examples run fine on git master, although this could well have been fixed ages ago.