Open Quuxplusone opened 9 years ago
Quuxplusone
commented
9 years ago It's under -Wdeprecated-register, and it's on by default:
$ cat t.cpp
void use(int);
int main() {
register int a = 42;
use(a);
}
$ clang -c t.cpp
t.cpp:3:3: warning: 'register' storage class specifier is deprecated [-
Wdeprecated-register]
register int a = 42;
^~~~~~~~~
1 warning generated.(In reply to comment #1)
> It's under -Wdeprecated-register, and it's on by default:
>
> $ cat t.cpp
> void use(int);
> int main() {
> register int a = 42;
> use(a);
> }
>
> $ clang -c t.cpp
> t.cpp:3:3: warning: 'register' storage class specifier is deprecated
> [-Wdeprecated-register]
> register int a = 42;
> ^~~~~~~~~
> 1 warning generated.
Hi, Reid!
I tried 3.5 on Linux and r223387 on Windows but it didn't produce warning for C
code.
According to
http://llvm.org/klaus/clang/commit/58df0426944c1bf8a80b6935bbea3815fc506474/ it
enabled for C++11.
Is it possible to enable it for C and C++ of older standards? Even not by
default?
Eugene.'register' is not deprecated in C, so -Wdeprecated-register doesn't seem like the right place for it.
I can see the desire to avoid using 'register' in new code, but it's also quite harmless so it seems more like a style issue than something to warn about.
Quuxplusone
commented
9 years ago (In reply to comment #3)
> 'register' is not deprecated in C, so -Wdeprecated-register doesn't seem
> like the right place for it.
>
> I can see the desire to avoid using 'register' in new code, but it's also
> quite harmless so it seems more like a style issue than something to warn
> about.
May be this warning could be implemented in Clang-Tidy, if it task is to fix
style issues?(In reply to comment #3)
> 'register' is not deprecated in C, so -Wdeprecated-register doesn't seem
> like the right place for it.
>
> I can see the desire to avoid using 'register' in new code, but it's also
> quite harmless so it seems more like a style issue than something to warn
> about.
True, but I think if the user explicitly passes -Wdeprecated-register on the
command line, then they should get the warning that we already have code for.
Normally, we use DefaultIgnore for this, but for this language-specific mode we
would need to add extra logic. I think we could take a patch for that.
This warning should still be off by default in C. C code has a habit of staying
old and crufty, while C++ seems to update or die.Parasoft C/C++test has this check (JSF-140-2).
Hi!
I think will be good idea to introduce warning for usage of register qualifier: most likely useless for optimization, but may still present in legacy code (when number of register variables may be much more then number of actual registers).
Eugene.