llvm-project.git/clang/test/CodeGen/bounds-checking-fam.cpp, branch users/nico/python-2 Unnamed repository; edit this file 'description' to name the repository. [clang] Introduce -fstrict-flex-arrays=<n> for stricter handling of flexible arrays 2022-07-18T10:45:52+00:00 serge-sans-paille sguelton@redhat.com 2022-06-28T09:01:55+00:00 f764dc99b37e1e6428724a61f36bcb49c015dc70 Some code [0] consider that trailing arrays are flexible, whatever their size. Support for these legacy code has been introduced in f8f632498307d22e10fab0704548b270b15f1e1e but it prevents evaluation of __builtin_object_size and __builtin_dynamic_object_size in some legit cases. Introduce -fstrict-flex-arrays=<n> to have stricter conformance when it is desirable. n = 0: current behavior, any trailing array member is a flexible array. The default. n = 1: any trailing array member of undefined, 0 or 1 size is a flexible array member n = 2: any trailing array member of undefined or 0 size is a flexible array member This takes into account two specificities of clang: array bounds as macro id disqualify FAM, as well as non standard layout. Similar patch for gcc discuss here: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101836 [0] https://docs.freebsd.org/en/books/developers-handbook/sockets/#sockets-essential-functions 
Some code [0] consider that trailing arrays are flexible, whatever their size.
Support for these legacy code has been introduced in
f8f632498307d22e10fab0704548b270b15f1e1e but it prevents evaluation of
__builtin_object_size and __builtin_dynamic_object_size in some legit cases.

Introduce -fstrict-flex-arrays=<n> to have stricter conformance when it is
desirable.

n = 0: current behavior, any trailing array member is a flexible array. The default.
n = 1: any trailing array member of undefined, 0 or 1 size is a flexible array member
n = 2: any trailing array member of undefined or 0 size is a flexible array member

This takes into account two specificities of clang: array bounds as macro id
disqualify FAM, as well as non standard layout.

Similar patch for gcc discuss here: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101836

[0] https://docs.freebsd.org/en/books/developers-handbook/sockets/#sockets-essential-functions