Bug 15315 – can break immutable with std.algorithm.move

Shown by Mike Parker in D.learn: http://forum.dlang.org/post/[email protected] ---- static struct ku { immutable int id; ~this() @safe {} } void main() @safe { ku k1 = ku(1); scope(exit) assert(k1.id == 1); /* fails */ ku k2 = ku(2); scope(exit) assert(k2.id == 2); /* fails too, because there's a destructor */ import std.algorithm: move; move(k2, k1); } ----

This should pass regardless of safe. The move function should simply copy the integer without overwriting it. This is because int does not have an elaborate postblit so it is cheap to copy.

Wait, what? Aren't *both* k1.id and k2.id *immutable*? How could move(k2,k1) be valid, since it would overwrite k1, which violates the immutability of k1.id?

Indeed, apologies. The target cannot be immutable.

@ntrel created dlang/phobos pull request #9032 "Fix Bugzilla 15315 - can break immutable with std.algorithm.move" fixing this issue: - Fix Bugzilla 15315 - can break immutable with std.algorithm.move https://github.com/dlang/phobos/pull/9032

dlang/phobos pull request #9032 "Fix Bugzilla 15315 - can break immutable with std.algorithm.move" was merged into master: - dad7820d2aea4937f1ea1edc3340b9a7d454352a by Nick Treleaven: Fix Bugzilla 15315 - can break immutable with std.algorithm.move https://github.com/dlang/phobos/pull/9032