try and work around OS_LIB_PATH_RELATIVIZER_BASE crash:

Author: lihaoyi

os/src/Path.scala

@@ -452,12 +452,28 @@ object Path extends PathMacros {
     val maybeBase = Option(System.getenv("OS_LIB_PATH_RELATIVIZER_BASE")).filter(_.nonEmpty)
     maybeBase match {
       case Some(base0) =>
-        pathRelativizerSerializer(Path(base0))
+        pathRelativizerSerializer(pathFromRawString(base0))
       case None =>
         rawPathSerializer
     }
   }
 
+  /**
+   * Parse a String path without depending on `pathSerializer` to avoid
+   * initialization cycles when constructing `defaultPathSerializer`.
+   */
+  private def pathFromRawString(raw: String): Path = {
+    val parsed =
+      if (driveRelative(raw)) Paths.get(s"$driveRoot$raw")
+      else Paths.get(raw)
+
+    if (parsed.iterator.asScala.count(_.startsWith("..")) > parsed.getNameCount / 2) {
+      throw PathError.AbsolutePathOutsideRoot
+    }
+
+    new Path(parsed.normalize())
+  }
+
   @experimental def pathRelativizerSerializer(base: os.Path): Serializer = new Serializer {
     private def serializeRelative(p: os.Path): Option[java.nio.file.Path] = {
       if (p.fileSystem == base.fileSystem && p.startsWith(base)) Some(p.relativeTo(base).toNIO)

os/test/src/PathTests.scala

@@ -575,25 +575,22 @@ object PathTests extends TestSuite {
       assert(x / "hello" == y)
     }
     test("pathRelativizerSerializer") {
-      def check(name: String)(cond: => Boolean): Unit = {
-        if (!cond) throw new java.lang.AssertionError(s"check failed: $name")
-      }
       val base = os.pwd / "base"
       val serializer = os.Path.pathRelativizerSerializer(base)
       os.Path.pathSerializer.withValue(serializer) {
         val inBase = base / "foo" / "bar"
         val outside = os.pwd / "outside"
 
-        check("serialize string in base")(inBase.toString == "foo/bar")
-        check("serialize nio in base")(inBase.toNIO == java.nio.file.Paths.get("foo/bar"))
-        check("serialize file in base")(inBase.toIO.getPath == new java.io.File("foo/bar").getPath)
+        assert(inBase.toString == "foo/bar")
+        assert(inBase.toNIO == java.nio.file.Paths.get("foo/bar"))
+        assert(inBase.toIO.getPath == new java.io.File("foo/bar").getPath)
 
-        check("deserialize string relative")(os.Path("foo/bar") == inBase)
-        check("deserialize nio relative")(os.Path(java.nio.file.Paths.get("foo/bar")) == inBase)
-        check("deserialize file relative")(os.Path(new java.io.File("foo/bar")) == inBase)
+        assert(os.Path("foo/bar") == inBase)
+        assert(os.Path(java.nio.file.Paths.get("foo/bar")) == inBase)
+        assert(os.Path(new java.io.File("foo/bar")) == inBase)
 
-        check("serialize string outside base")(outside.toString == outside.wrapped.toString)
-        check("serialize nio outside base")(outside.toNIO == outside.wrapped)
+        assert(outside.toString == outside.wrapped.toString)
+        assert(outside.toNIO == outside.wrapped)
       }
     }
   }