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Diffstat (limited to 'NEWS')
| -rw-r--r-- | NEWS | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/NEWS b/NEWS index 4c8bc924ce..cc20102fda 100644 --- a/NEWS +++ b/NEWS @@ -68,6 +68,23 @@ Deprecated and removed features, and other changes affecting compatibility: used by the Linux kernel. This affects the size and layout of those structures. +* An archaic GNU extension to scanf, under which '%as', '%aS', and '%a[...]' + meant to scan a string and allocate space for it with malloc, is now + restricted to programs compiled in C89 or C++98 mode with _GNU_SOURCE + defined. This extension conflicts with C99's use of '%a' to scan a + hexadecimal floating-point number, which is now available to programs + compiled as C99 or C++11 or higher, regardless of _GNU_SOURCE. + + POSIX.1-2008 includes the feature of allocating a buffer for string input + with malloc, using the modifier letter 'm' instead. Programs using + '%as', '%aS', or '%a[...]' with the old GNU meaning should change to + '%ms', '%mS', or '%m[...]' respectively. Programs that wish to use the + C99 '%a' no longer need to avoid _GNU_SOURCE. + + GCC's -Wformat warnings can detect most uses of this extension, as long + as all functions that call vscanf, vfscanf, or vsscanf are annotated with + __attribute__ ((format (scanf, ...))). + Changes to build and runtime requirements: * Python 3.4 or later is required to build the GNU C Library. |