musl - musl - an implementation of the standard library for Linux-based systems

add _DEFAULT_SOURCE feature profile as an alias for _BSD_SOURCE

as a result of commit ab8f6a6e42ff893041f7545a23e6d6a0edde07fb, this definition is now equivalent to the actual "default profile" which appears immediately below in features.h, and which defines both _BSD_SOURCE and _XOPEN_SOURCE. the intent of providing a _DEFAULT_SOURCE, which glibc also now provides, is to give applications a way to "get back" the default feature profile when it was lost either by compiler flags that inhibit it (such as -std=c99) or by library-provided predefined macros (such as -D_POSIX_C_SOURCE=200809L) which may inhibit exposure of features that were otherwise visible by default and which the application may need. without _DEFAULT_SOURCE, the application had encode knowledge of a particular libc's defaults, and such knowledge was fragile and subject to bitrot. eventually the names _GNU_SOURCE and _BSD_SOURCE should be phased out in favor of the more-descriptive and more-accurate _ALL_SOURCE and _DEFAULT_SOURCE, leaving the old names as aliases but using the new ones internally. however this is a more invasive change that would require extensive regression testing, so it is deferred.

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1 files changed, 4 insertions, 0 deletions