Bug 21220 – [DIP1000] scope variable may escape through scope dynamic array parameter

Scoped local array cannot go to outside scope, but currently the variable may escape to outside through scope dynamic array parameter. -------- import std; @safe: struct A { char[] value; } A f(scope A[] array) { return array[0]; // lifetime(array) to infinity } A g() { scope char[4] value = "test"; scope A a; a.value = value[]; return f([a]); // This is not error. } void h() { scope char[30] s = "123456789012345678901234567890"; writefln("%s", s); } void main() { auto a = g(); // 123456789012345678901234567890 // 1234[4] h(); writefln("%s[%d]", a.value, a.value.length); } -------- I think that this code should be compile error at `f([a])` line. Other variations are reported compile error. -------- A g() { scope char[4] value = "test"; scope A a; a.value = value[]; return f([a]); // Error: cannot take address of scope local array in @safe function g // scope A[1] array; // array[0].value = value[]; // return f(array[]); // Error: scope variable a may not be copied into allocated memory // scope A[] array = [a]; // return f(array); } --------

@RazvanN7 created dlang/dmd pull request #12204 "Fix Issue 21220 - [DIP1000] scope variable may escape through scope dynamic array parameter" fixing this issue: - Fix Issue 21220 - [DIP1000] scope variable may escape through scope dynamic array parameter https://github.com/dlang/dmd/pull/12204

Duplicate of 20505, which is itself a subset of 17764. *** This issue has been marked as a duplicate of issue 20505 ***