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

Section: 30.12 [c.files] Status: NAD Submitter: Jeffrey Yasskin Opened: 2011-03-23 Last modified: 2016-02-10

Priority: Not Prioritized

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View all issues with NAD status.

Discussion:

People often define structs and classes with fields named stdin, stdout, or stderr. According to 30.12 [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 30.12 [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.6 [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