Filed on behalf of Ben Taylor <benty@amazon.com>.

Simon Tooke did a prototype 8u build using newer versions of Xcode a year ago, see

https://github.com/stooke/jdk8u-xcode10/tree/master/jdk8u-patch

Simon's patches included a number of backports. These and others have been either backported to 8u or are awaiting maintainer approval.

JDK-8019470: Changes needed to compile JDK 8 on MacOS with clang compiler
JDK-8200550: Xcode 9.3 produce warning -Wexpansion-to-defined
JDK-8253375: OSX build fails with Xcode 12.0 (12A7209)
JDK-8230428: Cleanup dead CastIP node code in formssel.cpp
JDK-8077364: "if( !this )" construct prevents build on Xcode 6.3
JDK-8055754: filemap.cpp does not compile with clang
JDK-8033289: clang: clean up unused function warning
JDK-8239053: [8u] clean up undefined-var-template warnings
JDK-8239400: [8u] clean up delete-non-virtual-dtor warnings in HotSpot
JDK-8138820: JDK Hotspot build fails with Xcode 7.0.1
JDK-8034856: gcc warnings compiling src/solaris/native/sun/security/pkcs11
JDK-8074836: Resolve disabled warnings for libosxkrb5
JDK-8035054: JarFacade.c should not include ctype.h
JDK-8035287: gcc warnings compiling various libraries files
JDK-8129511: PlatformMidi.c:83 uses malloc without malloc header
JDK-8037825: Fix warnings and enable "warnings as errors" in serviceability native libraries
JDK-8043646: libosxapp.dylib fails to build on Mac OS 10.9 with clang
JDK-8250876: Fix issues with cross-compile on macos
JDK-8265238: [8u] [macos] build failure in OpenJDK8u after JDK-8211301 in older xcode

What remains to be done are makefile and a few source code changes not covered by the above. They amount to updated versions of the following.

For the root repo:

https://github.com/stooke/jdk8u-xcode10/blob/master/jdk8u-patch/jdk8u-buildfix1.patch
https://github.com/stooke/jdk8u-xcode10/blob/master/jdk8u-patch/jdk8u-buildfix2.patch
https://github.com/stooke/jdk8u-xcode10/blob/master/jdk8u-patch/jdk8u-c99.patch

For the hotspot repo:

https://github.com/stooke/jdk8u-xcode10/blob/master/jdk8u-patch/jdk8u-hotspot-c99.patch
https://github.com/stooke/jdk8u-xcode10/blob/master/jdk8u-patch/jdk8u-hotspot-mac.patch

For the jdk repo:

https://github.com/stooke/jdk8u-xcode10/blob/master/jdk8u-patch/jdk8u-jdk-c99.patch
https://github.com/stooke/jdk8u-xcode10/blob/master/jdk8u-patch/jdk8u-jdk-minversion.patch
https://github.com/stooke/jdk8u-xcode10/blob/master/jdk8u-patch/jdk8u-libcxxfix.patch