RFR(T): 8233530: gcc 5.4 build warning -Wc++14-compat after JDK-8233359

[Lindenmaier, Goetz]

Hi,

Is this happening only with gcc 5.4, or also with 7.3?
7.3 was the compiler listed for jdk 13: 
https://wiki.openjdk.java.net/display/Build/Supported+Build+Platforms

in other places, we check for the specific gcc version:
http://hg.openjdk.java.net/jdk/jdk/file/8623f75be895/src/hotspot/share/utilities/debug.hpp#l157
http://hg.openjdk.java.net/jdk/jdk/file/8623f75be895/src/hotspot/share/utilities/compilerWarnings_gcc.hpp#l62
This warning seems not to happen with gcc 8.3.
So should we, similarly, protect this place with __GNUG__ < 6? or < 8?
Else I would like to see a comment that states that a warning
was seen with gcc 5.4, so that this can be removed more easily
later on.
Don't need a new webrev for that...

Also, above places make decisions for gcc 4.
Do we still support gcc 4?
This change might not be working on gcc 4. PRAGMA_DIAG_PUSH is defined 
empty for gcc < 4.6.  (I think this does not matter.)
... Maybe, in a follow up, we should remove these checks for gcc 4 and 
force at least gcc 5 in jdk 14? 

Best regards,
  Goetz.


> -----Original Message-----
> From: hotspot-runtime-dev <hotspot-runtime-dev-bounces at openjdk.java.net>
> On Behalf Of Thomas Stüfe
> Sent: Dienstag, 5. November 2019 08:07
> To: Hotspot dev runtime <hotspot-runtime-dev at openjdk.java.net>
> Subject: RFR(T): 8233530: gcc 5.4 build warning -Wc++14-compat after JDK-
> 8233359
> 
> Hi all,
> 
> may I please have reviews for this small build fix:
> 
> Issue: https://bugs.openjdk.java.net/browse/JDK-8233530
> Webrev:
> http://cr.openjdk.java.net/~stuefe/webrevs/8233530-wc14-
> compat/webrev.00/webrev/
> Prior discussion:
> https://mail.openjdk.java.net/pipermail/hotspot-runtime-dev/2019-
> November/036726.html
> 
> Thank you,
> 
> Thomas