Bug 21626 – foreach create reference to rvalue tuple returned by front

If range return rvalue tuple from front and foreach unpack tuple then temporary value to front is ref and after leaving scope destructor is not called: import std.range; import std.stdio; import std.typecons; int created, destroyed; ///struct count destructions and constructions struct S{ int val; @disable this(); this(int val) { this.val = val; created++; } this(ref inout const typeof(this) rhs)inout { this.val = rhs.val; created++; } ~this() { destroyed++; } } //range, for each call of front return rvalue Tuple!(S, S) struct Generator(T){ int n; this(int n){ this.n = n; } @property Tuple!(T, T) front(){ return tuple(T(n), T(n)); } @property void popFront(){ n -= 1; } @property bool empty()const{ return n < 1; } } ///This work OK: void test_A(){ foreach(s; Generator!S(10)){ assert(s[0].val == s[1].val); } assert(created == destroyed); } ///This fail: void test_B(){ foreach(s1, s2; Generator!S(10)){ assert(s1.val == s2.val); } writeln(": created ", created, " vs destroyed ", destroyed); ///created != destroyed assert(created == destroyed); ///FAIL!! } void main() { test_A(); test_B(); } test_B AST: void test_B() { { Generator!(S) __r101 = __r101 = 0 , __r101.this(10); for (; !__r101.empty(); __r101.popFront()) { ref Tuple!(S, S) __front102 = __r101.front(); ///PROBLEM! reference to rvalue, destructor is not called! ref S s1 = __front102.__expand_field_0; ref S s2 = __front102.__expand_field_1; assert(s1.val == s2.val); } } writeln(": created ", created, " vs destroyed ", destroyed); assert(created == destroyed); }

Confirmed with dmd v2.108.0-rc.1.

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