Bug 13902 – Compiler allows escaping the address of part of a local

Currently the compiler disallows this: ref int fun() { int x; return x; // escape the address of a local } However, this goes unchecked: struct S { int x; } ref int fun() { S s; return s.x; // escape the address of part of a local } Direct member access is easy to check using the same logic, so I'm filing this as a bug. DIP25 addresses more sophisticated detection cases.

One more simple case, equivalent in fact because statically-sized arrays behave like structs: ref int lun() { int a[42]; return a[5]; } This should also be disallowed directly.

*** Issue 4232 has been marked as a duplicate of this issue. ***

*** Issue 4451 has been marked as a duplicate of this issue. ***

*** Issue 9537 has been marked as a duplicate of this issue. ***

Commits pushed to master at https://github.com/D-Programming-Language/druntime https://github.com/D-Programming-Language/druntime/commit/b526fbd89465cce8c2ab7bef84007438395effca Supplemental fix for issue 13902, don't return a slice to local static array. https://github.com/D-Programming-Language/druntime/commit/097bb6feccdfe48a79e06d9be23eb88864b57d54 Merge pull request #1094 from 9rnsr/fix13902 Supplemental fix for issue 13902, don't return a slice to local static array.

Commits pushed to master at https://github.com/D-Programming-Language/dmd https://github.com/D-Programming-Language/dmd/commit/dc6235bc932c5a829c9a69b276c93462917a8f09 fix Issue 13902 - Compiler allows escaping the address of part of a local To visualize the current scope behavior, I added fail_compilation/fail_scope.d. https://github.com/D-Programming-Language/dmd/commit/0829ec3913fa27f24a1a952be7fca012126aa959 Merge pull request #4277 from 9rnsr/fix13902 Issue 13902 - Compiler allows escaping the address of part of a local

Commits pushed to 2.067 at https://github.com/D-Programming-Language/druntime https://github.com/D-Programming-Language/druntime/commit/b526fbd89465cce8c2ab7bef84007438395effca Supplemental fix for issue 13902, don't return a slice to local static array. https://github.com/D-Programming-Language/druntime/commit/097bb6feccdfe48a79e06d9be23eb88864b57d54 Merge pull request #1094 from 9rnsr/fix13902

Commits pushed to 2.067 at https://github.com/D-Programming-Language/dmd https://github.com/D-Programming-Language/dmd/commit/dc6235bc932c5a829c9a69b276c93462917a8f09 fix Issue 13902 - Compiler allows escaping the address of part of a local https://github.com/D-Programming-Language/dmd/commit/0829ec3913fa27f24a1a952be7fca012126aa959 Merge pull request #4277 from 9rnsr/fix13902