Bug 20245 – DIP1000: Should infer scope when taking address of ref

For -preview=dip1000 : @safe int* foo(ref int x) { int* a = &x; return a; } This should infer `scope` for `a`, and then issue an error on returning `a`. The following should not compile: @safe int** foo(ref scope int* x) { int** a = &x; return a; } because there's not way to attach `scope` to anything but the head, i.e. no scope pointers to scope pointers to int. This should compile successfully: @safe int* foo(return ref int x) { int* a = &x; return a; }

Works fine with current master: ---------------------------------------------- @safe int** foo(ref scope int* x) { int** a = &x; return a; } @safe int* fooRet(return ref int x) { int* a = &x; return a; } ---------------------------------------------- ./generated/linux/release/64/dmd -c -o- -dip1000 dip_escape.d dip_escape.d(3): Error: cannot take address of `scope` parameter `x` in `@safe` function `foo

(In reply to moonlightsentinel from comment #1) > Works fine with current master: > > ---------------------------------------------- > @safe int** foo(ref scope int* x) > { > int** a = &x; > return a; > } That only works because `x` is a `scope` pointer, and the compiler can't give double `scope` to it when taking its address. The original example of a non-scope ref still compiles: ``` @safe: int* foo(ref int x) { int* a = &x; return a; } void main() { int* ptr; { int x; ptr = foo(x); } // x escaped via ptr here } ```

*** Issue 21212 has been marked as a duplicate of this issue. ***

@dkorpel created dlang/dmd pull request #12812 "Fix issue 20245 - address of ref should be scope" fixing this issue: - fix issue 20245 - address of ref should be scope https://github.com/dlang/dmd/pull/12812

dlang/dmd pull request #12812 "Fix issue 20245 - address of ref should be scope" was merged into master: - 47fa750bc76a5835fe8c547fed30133ed2a12a8a by dkorpel: fix issue 20245 - address of ref should be scope https://github.com/dlang/dmd/pull/12812