Block objects [1] are a C-level syntactic and runtime feature. They
are similar to standard C functions, but in addition to executable
code they may also contain variable bindings to automatic (stack)
or managed (heap) memory. A block can therefore maintain a set of
state (data) that it can use to impact behavior when executed.
This port is based on Apple's GCC 5646 with some bugfixes from
Apple GCC 5666.3. It has some small differences with the support
in clang, which remains the recommended compiler.
Perhaps the most notable difference is that in GCC that __block
is not actually a keyword, but a macro. There will be workaround
for this issue in a near future. Other issues can be consulted in
the clang documentation [2]
For better compatiblity with Apple's GCC and llvm-gcc some related
fixes and features from Apple have been included. Support for the
non-standard nested functions in GCC is now off by default.
No effort was made to update the ObjC support since FreeBSD doesn't
carry ObjC in the base system, but some of the code crept in and
was more difficult to remove than to adjust.
Reference:
[1]
https://developer.apple.com/library/mac/documentation/Cocoa/Conceptual/Blocks/Articles/00_Introduction.html
[2]
http://clang.llvm.org/compatibility.html#block-variable-initialization
Obtained from: Apple GCC 4.2
MFC after: 3 weeks
Apple GCC has extensions to support for both label attributes and
an "unavailable" attribute. These are critical for objc but are
also useful in regular C/C++.
Apparently at least the label attributes might have found their way to
upstream GCC but the code doesn't seem available on the GPLv2 tree so
we are taking the code directly from Apple. To make this clearer we
are preserving the annoying "APPLE LOCAL" tags and the ChangeLogs
when they are available.
Obtained from: Apple GCC 4.2 - 5531
MFC after: 3 weeks
original intent, but the functionality wasn't implemented until after
gcc 4.2 was released. However, if you compiled a program that would
behave differently before and after this change, gcc 4.2 would have
warned you; hence, everything currently in the base system is
unaffected by this change. This patch also adds additional warnings
about certain inline function-related bogosity, e.g., using a
static non-const local variable in an inline function.
These changes were merged from a snapshot of gcc mainline from March
2007, prior to the GPLv3 switch. I then ran the regression test suite
from a more recent gcc snapshot and fixed the important bugs it found.
I also squelched the following warning unless -pedantic is specified:
foo is static but used in inline function bar which is not static
This is consistent with LLVM's behavior, but not consistent with gcc 4.3.
Reviewed by: arch@
attribute. It is like the existing "printf" archetype, except that
it doesn't complain if the format string is a null pointer. See
the node "Function Attributes" in the GCC info pages if you don't
know what this is all about.
This change will allow us to add format string checking for the
err(3) family of functions.
non-i386, non-unix, and generatable files have been trimmed, but can easily
be added in later if needed.
gcc-2.7.2.1 will follow shortly, it's a very small delta to this and it's
handy to have both available for reference for such little cost.
The freebsd-specific changes will then be committed, and once the dust has
settled, the bmakefiles will be committed to use this code.
