A couple of users have reported that when building the JDK on macos with XCode 16.3, the build generates compiler warnings which causes the JDK build to fail. The warnings are listed at the end of this issue.

Workarounds exist to get past these warnings and build the JDK successfully. Using a lower versioned XCode (for example 15.4) details here https://github.com/openjdk/jdk/blob/master/doc/building.md#apple-xcode or configuring the JDK build to use "--disable-warnings-as-errors" option (details here https://github.com/openjdk/jdk/blob/master/doc/building.md#problems-with-the-build-environment) are known to help get past this issue.

Warnings generated during the build are as follows:

src/java.desktop/macosx/native/libjsound/PLATFORM_API_MacOSX_Ports.cpp:127:39: error: variable length arrays in C++ are a Clang extension [-Werror,-Wvla-cxx-extension]
127 | AudioDeviceID devices[count];
| ^~~~~
src/java.desktop/macosx/native/libjsound/PLATFORM_API_MacOSX_Ports.cpp:127:39: note: read of non-const variable 'count' is not allowed in a constant expression
src/java.desktop/macosx/native/libjsound/PLATFORM_API_MacOSX_Ports.cpp:126:21: note: declared here
126 | int count = size/sizeof(AudioDeviceID);
| ^
src/java.desktop/macosx/native/libjsound/PLATFORM_API_MacOSX_Ports.cpp:151:42: error: variable length arrays in C++ are a Clang extension [-Werror,-Wvla-cxx-extension]
151 | AudioObjectID controlIDs[count];
| ^~~~~
src/java.desktop/macosx/native/libjsound/PLATFORM_API_MacOSX_Ports.cpp:151:42: note: read of non-const variable 'count' is not allowed in a constant expression
src/java.desktop/macosx/native/libjsound/PLATFORM_API_MacOSX_Ports.cpp:150:21: note: declared here
150 | int count = size / sizeof(AudioObjectID);
| ^
src/java.desktop/macosx/native/libjsound/PLATFORM_API_MacOSX_Ports.cpp:483:38: error: variable length arrays in C++ are a Clang extension [-Werror,-Wvla-cxx-extension]
483 | AudioObjectID controlIDs[mixer->deviceControlCount];
| ^~~~~~~~~~~~~~~~~~~~~~~~~
src/java.desktop/macosx/native/libjsound/PLATFORM_API_MacOSX_Ports.cpp:483:38: note: read of non-constexpr variable 'mixer' is not allowed in a constant expression
src/java.desktop/macosx/native/libjsound/PLATFORM_API_MacOSX_Ports.cpp:458:16: note: declared here
458 | PortMixer *mixer = (PortMixer *)id;
| ^
src/java.desktop/macosx/native/libjsound/PLATFORM_API_MacOSX_Ports.cpp:527:34: error: variable length arrays in C++ are a Clang extension [-Werror,-Wvla-cxx-extension]
527 | AudioControl* volumeControls[totalChannels+1]; // 0 - for master channel
| ^~~~~~~~~~~~~~~
src/java.desktop/macosx/native/libjsound/PLATFORM_API_MacOSX_Ports.cpp:527:34: note: read of non-const variable 'totalChannels' is not allowed in a constant expression
src/java.desktop/macosx/native/libjsound/PLATFORM_API_MacOSX_Ports.cpp:524:9: note: declared here
524 | int totalChannels = GetChannelCount(mixer->deviceID, port->scope == kAudioDevicePropertyScopeOutput ? 1 : 0);
| ^
src/java.desktop/macosx/native/libjsound/PLATFORM_API_MacOSX_Ports.cpp:529:32: error: variable length arrays in C++ are a Clang extension [-Werror,-Wvla-cxx-extension]
529 | AudioControl* muteControls[totalChannels+1]; // 0 - for master channel
| ^~~~~~~~~~~~~~~
src/java.desktop/macosx/native/libjsound/PLATFORM_API_MacOSX_Ports.cpp:529:32: note: read of non-const variable 'totalChannels' is not allowed in a constant expression
src/java.desktop/macosx/native/libjsound/PLATFORM_API_MacOSX_Ports.cpp:524:9: note: declared here
524 | int totalChannels = GetChannelCount(mixer->deviceID, port->scope == kAudioDevicePropertyScopeOutput ? 1 : 0);
| ^
src/java.desktop/macosx/native/libjsound/PLATFORM_API_MacOSX_Ports.cpp:775:24: error: variable length arrays in C++ are a Clang extension [-Werror,-Wvla-cxx-extension]
775 | Float32 subVolumes[control->controlCount];
| ^~~~~~~~~~~~~~~~~~~~~
src/java.desktop/macosx/native/libjsound/PLATFORM_API_MacOSX_Ports.cpp:775:24: note: read of non-constexpr variable 'control' is not allowed in a constant expression
src/java.desktop/macosx/native/libjsound/PLATFORM_API_MacOSX_Ports.cpp:772:18: note: declared here
772 | PortControl *control = (PortControl *)controlIDV;
| ^
src/java.desktop/macosx/native/libjsound/PLATFORM_API_MacOSX_Ports.cpp:824:24: error: variable length arrays in C++ are a Clang extension [-Werror,-Wvla-cxx-extension]
824 | Float32 subVolumes[control->controlCount];
| ^~~~~~~~~~~~~~~~~~~~~
src/java.desktop/macosx/native/libjsound/PLATFORM_API_MacOSX_Ports.cpp:824:24: note: read of non-constexpr variable 'control' is not allowed in a constant expression
src/java.desktop/macosx/native/libjsound/PLATFORM_API_MacOSX_Ports.cpp:818:18: note: declared here
818 | PortControl *control = (PortControl *)controlIDV;
| ^
7 errors generated.
make[3]: *** [build/macosx-aarch64-server-release/support/native/java.desktop/libjsound/PLATFORM_API_MacOSX_Ports.o] Error 1