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### 2043. `std{in,out,err}` should be usable as field names

Section: 31.13 [c.files] Status: NAD Submitter: Jeffrey Yasskin Opened: 2011-03-23 Last modified: 2016-01-28

Priority: Not Prioritized

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Discussion:

People often define structs and classes with fields named `stdin`, `stdout`, or `stderr`. According to 31.13 [c.files], though, these are macros.

glibc defines them to themselves, allowing their non-portable use as field names, while the Mac OS X libc defines them to either `__stdoutp` or `(&__sF[1])`, etc depending on `__DARWIN_UNIX03`. It's possible to allow their use while, as far as I can see, only requiring minor changes to various libc's, so C++1x should allow it.

[ 2011 Bloomington ]

Closed as NAD. This is an extension request that has been an issue for over 20 years. Supporting the extension would place a burden on the underlying C library that we may not be in a position to influence.

Proposed resolution:

This wording is relative to the FDIS.

1. In 31.13 [c.files] add "stderr", "stdin", and "stdout" to a new Values section in Table 134 — Header `<cstdio>` synopsis:

   > 134 — Header `<cstdio>` synopsis
   > Type Name(s)
   > Macros:
   > `BUFSIZ` | `FOPEN_MAX` | `SEEK_CUR` | `TMP_MAX` | `_IONBF` | `stdout`
   > `EOF` | `L_tmpnam` | `SEEK_END` | `_IOFBF` | `stderr` |
   > `FILENAME_MAX` | `NULL <cstdio>` | `SEEK_SET` | `_IOLBF` | `stdin` |
   > Types: | `FILE` | `fpos_t` | `size_t <cstdio>` |  |
   > Functions:
   > …
   > Values:
   > `stderr` | `stdin` | `stdout` |  |  |

2. Add a new paragraph after paragraph 2 as indicated:

   > 2 Calls to the function `tmpnam` with an argument of `NULL` may introduce a data race (17.6.5.9) with other calls to `tmpnam` with an argument of `NULL`.
   > See also: ISO C 7.9, Amendment 1 4.6.2.

   > ? The macros `stderr`, `stdin`, and `stdout` shall expand to `stderr`, `stdin`, and `stdout`, respectively. [Note: This allows uses of `#ifdef` to detect their presence, while allowing code in other scopes to use them as identifiers. — end note]

3. In C.7 [diff.library] add "stderr", "stdin", and "stdout" to Table 150 — Standard values:

   > Table 150 — Standard values
   > `CHAR_BIT` | `FLT_DIG` | `INT_MIN` | `MB_LEN_MAX`
   > …
   > … | … | … | `SHRT_MIN`
   > … | … | … | `stderr`
   > … | … | … | `stdin`
   > … | … | … | `stdout`
   > … | … | … | `UCHAR_MAX`
   > …