Re-enable Scala Native (0.5.8); keep ZipOps JVM-only; split zip tests to JVM (com-lihaoyi#400)

- Enable Native tests with nativeLinkStubs=true; update build.mill
- Move ZipOps to os/src-jvm; add shared placeholder for Native
- Move zip/unzip tests to os/test/src-jvm; add CheckerZipTests and
Native placeholder suite
- Stabilize FilesystemMetadataTests.isExecutable
- Docs: README note on JVM-only Zip APIs and changelog

Fixes com-lihaoyi#395

---------

Signed-off-by: Rishi Jat <[email protected]>

Author: rishi-jat

Readme.adoc

@@ -1220,6 +1220,11 @@ os.list(tempDir) ==> Seq(tempDir / "file")
 
 === Zip & Unzip Files
 
+[NOTE]
+====
+JVM only: Zip-related APIs are available on the JVM but not on Scala Native. The following symbols are JVM-only and are not defined on Native builds: `os.zip`, `os.unzip`, `os.zip.stream`, `os.unzip.stream`, `os.unzip.list`, and `os.zip.open`.
+====
+
 ==== `os.zip`
 
 [source,scala]
@@ -2579,6 +2584,10 @@ string, int or set representations of the `os.PermSet` via:
 
 == Changelog
 
+=== 0.11.6
+
+* Re-enabled Scala Native builds (tested with Scala Native 0.5.8). Zip APIs remain JVM-only.
+
 === 0.11.5
 
 * Dropped support for Scala-Native, until https://github.com/com-lihaoyi/os-lib/issues/395[Fix and re-enable Scala-Native build (500USD Bounty)]

build.mill

@@ -234,14 +234,23 @@ object os extends Module {
     }
   }
 
-  /*object native extends Cross[OsNativeModule](scalaVersions)
+  object native extends Cross[OsNativeModule](scalaVersions)
   trait OsNativeModule extends OsModule with ScalaNativeModule {
-    def scalaNativeVersion = "0.5.2"
+    def scalaNativeVersion = "0.5.9"
+    
+    // Configurable native mode for debugging/performance testing
+    def nativeMode = sys.props.get("native.mode") match {
+      case Some("release-fast") => mill.scalanativelib.api.ReleaseMode.ReleaseFast  
+      case Some("release-full") => mill.scalanativelib.api.ReleaseMode.ReleaseFull
+      case _ => mill.scalanativelib.api.ReleaseMode.Debug
+    }
+    
     object test extends ScalaNativeTests with OsLibTestModule {
+      // Keep stubs linked to tolerate optional symbols across platforms
       def nativeLinkStubs = true
     }
     object nohometest extends ScalaNativeTests with OsLibTestModule
-  }*/
+  }
 
   object watch extends Module {
     object jvm extends Cross[WatchJvmModule](scalaVersions)

debug-subprocess-loop.sh

@@ -0,0 +1,52 @@
+#!/bin/bash
+
+# Script to help debug intermittent subprocess failures locally
+# Usage: ./debug-subprocess-loop.sh [iterations] [target]
+
+ITERATIONS=${1:-50}
+TARGET=${2:-"test.os.SubprocessTests"}
+SCALA_VERSION="2.13.16"
+
+echo "Running $TARGET in loop for $ITERATIONS iterations..."
+echo "Set SUBPROCESS_STRESS_ITERATIONS env var to control stress test iterations"
+
+SUCCESS_COUNT=0
+FAILURE_COUNT=0
+
+for i in $(seq 1 $ITERATIONS); do
+    echo "=== Iteration $i/$ITERATIONS ==="
+    
+    if ./mill -i "os.jvm[$SCALA_VERSION].test.testOnly" "$TARGET" 2>&1; then
+        SUCCESS_COUNT=$((SUCCESS_COUNT + 1))
+        echo "✓ Iteration $i: SUCCESS"
+    else
+        FAILURE_COUNT=$((FAILURE_COUNT + 1))
+        echo "✗ Iteration $i: FAILED"
+        
+        # Optionally stop on first failure
+        if [ "$3" = "--stop-on-failure" ]; then
+            echo "Stopping on first failure as requested"
+            break
+        fi
+    fi
+    
+    # Small delay between runs
+    sleep 0.1
+done
+
+echo ""
+echo "=== SUMMARY ==="
+echo "Total iterations: $ITERATIONS"
+echo "Successes: $SUCCESS_COUNT"
+echo "Failures: $FAILURE_COUNT"
+echo "Success rate: $(( SUCCESS_COUNT * 100 / (SUCCESS_COUNT + FAILURE_COUNT) ))%"
+
+if [ $FAILURE_COUNT -gt 0 ]; then
+    echo ""
+    echo "Failures detected! This may help reproduce the CI issue."
+    exit 1
+else
+    echo ""
+    echo "All tests passed. Try increasing iterations or running under stress."
+    exit 0
+fi