Bug 12226 – functions can return local stack-allocated objects by reference

An auto ref function can return a local stack-allocated struct by reference causing undefined behavior when executed. Sample code: http://pastebin.com/rvcNdjAE

(In reply to badlink from comment #0) > Sample code: http://pastebin.com/rvcNdjAE All sample code should be attached in bugzilla, or directly written in comment. ---------------- import std.stdio; void main() { auto a = Vec3f([0, 0, 0]); a += a * 0; writeln(a.array); // prints random values like [-1.13483, 4.2039e-45, -1.13482] assert(a == Vec3f([0, 0, 0])); // fails } alias Vector!(3, float) Vec3f; struct Vector(int size, T) { T[size] array; auto ref opBinary(string op)(T rhs) const if (op == "+" || op == "-" || op == "*" || op == "/") { Vector vector = this; mixin("return vector" ~ op ~ "= rhs;"); } auto ref opOpAssign(string op)(T rhs) if (op == "+" || op == "-" || op == "*" || op == "/") { mixin("array[] " ~ op ~ "= rhs;"); return this; } auto opOpAssign(string op)(const ref Vector rhs) // auto opOpAssign(string op)(const Vector rhs) // witouth ref everything works if (op == "+" || op == "-") { mixin("array[] " ~ op ~ "= rhs.array[];"); return this; } } ----------------

The example doesn't compile today because it's passing an rvalue to a ref parameter, but returning ref variables is now caught by dip25.