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digitalmars.D.bugs - [Issue 14246] New: proper destruction of partially constructed


          Issue ID: 14246
           Summary: proper destruction of partially constructed
           Product: D
           Version: D2
          Hardware: x86_64
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P1
         Component: DMD
          Assignee: nobody puremagic.com
          Reporter: schuetzm gmx.net

Currently, when a constructor throws, it will not call destructors of already
initialized member fields. The user is responsible for catching exceptions or
using `scope(failure)` and cleaning up manually. Of course, this is error prone
and can easily be forgotten.

I suggest to apply the same heuristic to mutable fields that is also use for
tracking the initialization of immutable fields: The first "assignment" to a
field must not appear in a loop or after a label, and calls the constructor
instead of opAssign(). For immutable and const fields, no further writes are
allowed; mutable fields can be changed as desired.

At each point where an exception can occur, the compiler is then aware which
fields have already been initialized, and can call their destructor.

Mar 04 2015