RFR: JDK-8155587: Cross compilation may cause compiler warnings for "build" compiler

[Chris Plummer]

Hi Erik,

I can confirm the changes resolve the issues I was having. I looked at 
the changes, but don't really have the background to comment on them.

thanks,

Chris

On 5/10/16 9:41 AM, Erik Joelsson wrote:
> Hello,
>
> When cross compiling, we compile a subset of the jdk for the build 
> host to be able to run jmod and jlink. Configure sets up a toolchain 
> for this through variables prefixed "BUILD_" (BUILD_CC etc). The new 
> nifty macro we have for conditionally setting compiler flags depending 
> on the version of the compiler is currently unaware of this. The 
> result is that if the compiler version for the target and build 
> toolchain differ, the macro will provide the wrong compiler flags.
>
> This patch makes the version check macro able to handle both the 
> target and build toolchain. It also fixes the 
> BUILD_CC_DISABLE_WARNING_PREFIX variable which is currently always 
> empty. The result is that our cross compile configurations at Oracle 
> no longer emits warnings from the build toolchain.
>
> Bug: https://bugs.openjdk.java.net/browse/JDK-8155587
> Webrev: http://cr.openjdk.java.net/~erikj/8155587/webrev.top.01/
>
> /Erik