Hi Martin,
A followup, what is the subtlety that makes it beneficial to wrap
even a single statement in a do {} while (0)?
It makes sense for macros with multiple statements but not for a single
statement substitution of expressions.
For a single statement (w/o ';'), it seems like a redundant overhead
that does not solve an issue.
Thanks, Roger
On 1/14/2014 5:20 PM, Martin Buchholz wrote:
On Tue, Jan 14, 2014 at 7:54 AM, roger riggs <roger.ri...@oracle.com
<mailto:roger.ri...@oracle.com>> wrote:
Hi David,
The CHECK_RETURN macros have existed in java.net <http://java.net>
for some time and
I have not seen any empty statement warnings.
The CHECK_EXCEPTION macros are new and does not have any uses yet.
I don't plan to do any wholesale modification of current sources.
The macros always produce a valid statement; (though my c/c++ may
be a bit rusty).
Macros should not generally be complete statements, including
semicolons; then the source code looks like this:
FOO()
which looks (including to emacs) like someone forgot the trailing
semicolon.
Instead, these macros should be written using the "well-known" do (
... ) while (0) idiom, e.g.
#define CHECK_NULL(x) do { if ((x) == NULL) return; } while (0)
(Note that it has been requested to rename the macros to include a
JNU_prefix
to be consistent with other macros in jni_util.h. I will propose a
separate set of changes for that).
Roger
On 1/13/2014 9:51 PM, David Holmes wrote:
Hi Roger,
webrev:
http://cr.openjdk.java.net/~rriggs/webrev-check-exception-8030875/
<http://cr.openjdk.java.net/%7Erriggs/webrev-check-exception-8030875/>
Do these macro definitions not cause "empty statement"
warnings from the compiler? (Existing ones have the same
problem I guess)
Also I don't see any use of the CHECK_EXCEPTION macros? In
fact the bulk of changes here seem completely unrelated to the
"exception" aspect of this CR.
Cheers,
David
[1] https://bugs.openjdk.java.net/browse/JDK-8030875
