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### 3675. `std::ios_base::iword/pword` might be misspecified

Section: 29.5.2.6 [ios.base.storage] Status: New Submitter: Jiang An Opened: 2022-02-14 Last modified: 2022-03-04

Priority: 4

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Discussion:

Currently 29.5.2.6 [ios.base.storage] p5 and p8 say "On failure, a valid `long&/void*&` initialized to `0`". Such wording seems wrong, because a `long&/void*&` variable or return value can't be initialized with `0`. And the values of referenced objects may be underspecified, because an implementation may reuse the same `long/void*` objects on failure, and thus it's insufficient to specify the initial values of these objects only.

[2022-03-04; Reflector poll]

Set priority to 4 after reflector poll.

Proposed resolution:

This wording is relative to N4901.

1. Modify 29.5.2.6 [ios.base.storage] as indicated:

   >     long& iword(int idx);

   > > -3- […]

   > > -4- […]

   > > -5- Returns: On success `iarray[idx]`. On failure, an valid lvalue of type `long&` with value `0L` initialized to `0`.

   >     void*& pword(int idx);

   > > -6- […]

   > > -7- […]

   > > -8- Returns: On success `parray[idx]`. On failure, an valid lvalue of type `void*&` with a null pointer value initialized to `0`.

   > > -9- Remarks: After a subsequent call to `pword(int)` for the same object, the earlier return value may no longer be valid.