On 06/10/2020 17:55, Joel Sherrill wrote:
On Tue, Oct 6, 2020 at 10:41 AM Sebastian Huber
<sebastian.hu...@embedded-brains.de
<mailto:sebastian.hu...@embedded-brains.de>> wrote:
On 06/10/2020 17:34, Joel Sherrill wrote:
>
> On Tue, Oct 6, 2020 at 9:46 AM Sebastian Huber
> <sebastian.hu...@embedded-brains.de
<mailto:sebastian.hu...@embedded-brains.de>
> <mailto:sebastian.hu...@embedded-brains.de
<mailto:sebastian.hu...@embedded-brains.de>>> wrote:
>
> On 06/10/2020 16:37, Joel Sherrill wrote:
>
> > How does it break the API? It looks like a change of
annotation.
> > Shouldn't be a big deal unless I am misunderstanding
something.
>
> Please have a look at:
>
> https://lists.rtems.org/pipermail/devel/2020-October/062577.html
>
>
> Looks like basically the same code. What does this break? Why
the concern?
The C11/C++11 attribute syntax is less flexible compared to the GNU
attributes. For example:
echo "_Noreturn void ok(void);" > test.c
echo "void error(void) _Noreturn;" >> test.c
gcc test.c
test.c: In function ‘error’:
test.c:2:1: error: ‘_Noreturn’ in empty declaration
void error(void) _Noreturn;
^~~~
test.c:2:18: warning: empty declaration
void error(void) _Noreturn;
^~~~~~~~~
test.c:2:1: error: expected ‘{’ at end of input
void error(void) _Noreturn;
^~~~
Yuck. I can see why they did the placement kind of. Makes it like const
or static but it uses an odd keyword with leading _ and capital letter
which is rather insane.
All new keywords in C are like this. You can include <stdnoreturn.h> to
get something without the underscore.
What's the positive value for doing this? Does llvm or some static
analyser like it better?
The positive thing is being in line with the standard.
C11 has improvements but it also has more than one thing I
question if they really thought through. :(
Yes, I guess not every C compiler vendor liked the GNU attribute stuff.
C++11 has a similar issue:
[[noreturn]] void ok(void);
void error(void) [[noreturn]];
g++ test.cc
test.cc:2:29: warning: attribute ignored [-Wattributes]
void error(void) [[noreturn]];
^
test.cc:2:29: note: an attribute that appertains to a type-specifier is
ignored
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