To help detect common kinds of memory (and other resource) management bugs, GCC 11 adds support for the detection of mismatched calls to allocation and deallocation functions. At each call site to a known deallocation function GCC checks the set of allocation functions the former can be paired with and, if the two don't match, issues a -Wmismatched-dealloc warning (something similar happens in C++ for mismatched calls to new and delete). GCC also uses the same mechanism to detect attempts to deallocate objects not allocated by any allocation function (or pointers past the first byte into allocated objects) by -Wfree-nonheap-object.
This support is enabled for built-in functions like malloc and free. To extend it beyond those, GCC extends attribute malloc to designate a deallocation function to which pointers returned from the allocation function may be passed to deallocate the allocated objects. Another, optional argument designates the positional argument to which the pointer must be passed.
This change is the first step in enabling this extended support for Glibc.
c1760eaf3b Enable support for GCC 11 -Wmismatched-dealloc.
include/programs/xmalloc.h | 8 ++---
libio/Makefile | 2 +-
libio/stdio.h | 64 +++++++++++++++++++++++-------------
libio/tst-freopen.c | 37 +++++++++++++++++++++
libio/tst-popen1.c | 4 +--
libio/tst-wmemstream1.c | 35 ++++++++++++++++++++
libio/tst-wmemstream5.c | 57 ++++++++++++++++++++++++++++++++
malloc/malloc.h | 11 ++++---
misc/sys/cdefs.h | 11 +++++++
stdlib/Makefile | 3 +-
stdlib/stdlib.h | 16 ++++++---
stdlib/tst-realpath.c | 82 ++++++++++++++++++++++++++++++++++++++++++++++
wcsmbs/wchar.h | 19 +++++++++--
13 files changed, 308 insertions(+), 41 deletions(-)