[cfloersch]

Problem

ScipWriter creates its temporary output file with the PosixFilePermissions attribute rw-r--r--:

Files.createTempFile("scip-aggregator", "index.scip",
    PosixFilePermissions.asFileAttribute(PosixFilePermissions.fromString("rw-r--r--")));

On file systems that do not support POSIX permissions, such as NTFS on Windows, this throws:

java.lang.UnsupportedOperationException: 'posix:permissions' not supported as initial attribute

scip-java aggregate therefore exits before it writes index.scip. This affects anything that runs the aggregator on Windows, including running ScipJava aggregate from a Maven build.

ScipWriter is the only class in scip-aggregator, scip-java, scip-javac and scip-shared that uses POSIX file permissions.

Fix

Create the temp file with the rw-r--r-- attribute only when the default file system reports the posix attribute view. Otherwise create it with the default permissions. Behavior on POSIX file systems is unchanged.

Testing

Added ScipWriterTest, which creates a ScipWriter, builds an empty index into a temp directory, and asserts the output file exists. It does not simulate a non-POSIX file system, so it exercises the fix only on Windows runners.

• Without the fix, on Windows 11 with JDK 21: the test fails with the exception above.
• With the fix: gradle :scip-aggregator:test and gradle spotlessCheck pass.
• Validated Posix system - Fedora 44