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digitalmars.D.bugs - [Issue 21225] New: preview=dtorfields inserts unnecessary dtor call


          Issue ID: 21225
           Summary: preview=dtorfields inserts unnecessary dtor call in
                    nothrow ctors
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: normal
          Priority: P1
         Component: dmd
          Assignee: nobody puremagic.com
          Reporter: moonlightsentinel disroot.org

The following code fails to compile with `-preview=dtorfields`:

struct Nothrow
    ~this() {}

struct NothrowConstructor
    Nothrow member;
    this(int) pure nothrow {}


 Error: `pure` constructor `NothrowConstructor.this` cannot call impure
destructor `NothrowConstructor.~this`

The code currently fails to compile because the compiler rewrites the
user-defined constructor as:

    <Old constructor>
catch (Exception e)
    throw e;

This causes the attribute missmatch (NothrowConstructor.~this not pure) albeit
the catch block is unreachable (unless the old constructor violates it's
`nothrow guarantee - which is UB anyway)

Sep 04 2020