Fix #12604: DefaultSettingsBuilder dead Windows drive-relative path handling

impl/maven-impl/src/main/java/org/apache/maven/impl/DefaultSettingsBuilder.java

@@ -21,7 +21,6 @@
 import javax.xml.stream.Location;
 import javax.xml.stream.XMLStreamException;
 
-import java.io.File;
 import java.io.IOException;
 import java.io.InputStream;
 import java.nio.file.Path;
@@ -128,11 +127,13 @@ public SettingsBuilderResult build(SettingsBuilderRequest request) throws Settin
                     .build();
         }
 
-        // for the special case of a drive-relative Windows path, make sure it's absolute to save plugins from trouble
+        // resolve relative local repository paths to absolute to save plugins from trouble.
+        // paths containing property placeholders like ${user.home} must be left as-is
+        // so that later interpolation can resolve them.
         String localRepository = effective.getLocalRepository();
         if (localRepository != null && !localRepository.isEmpty()) {
             Path file = Paths.get(localRepository);
-            if (!file.isAbsolute() && file.toString().startsWith(File.separator)) {
+            if (!file.isAbsolute() && !localRepository.contains("${")) {
                 effective = effective.withLocalRepository(file.toAbsolutePath().toString());
             }
         }

impl/maven-impl/src/test/java/org/apache/maven/impl/DefaultSettingsBuilderFactoryTest.java

@@ -42,6 +42,7 @@
 import org.mockito.junit.jupiter.MockitoExtension;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
@@ -160,6 +161,17 @@ void testSettingsWithDuplicateServersIds() throws Exception {
                 problems.problems().findFirst().orElseThrow().getMessage());
     }
 
+    @Test
+    void testRelativeLocalRepositoryIsResolvedToAbsolute() {
+        Settings settings = execute("settings-relative-local-repo").getEffectiveSettings();
+
+        String localRepository = settings.getLocalRepository();
+        assertNotNull(localRepository);
+        assertFalse(localRepository.isEmpty());
+        Path repoPath = Paths.get(localRepository);
+        assertTrue(repoPath.isAbsolute(), "Relative local repository should be resolved to absolute");
+    }
+
     private Path getSettings(String name) {
         return Paths.get("src/test/resources/settings/" + name + ".xml").toAbsolutePath();
     }

impl/maven-impl/src/test/resources/settings/settings-relative-local-repo.xml

@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="UTF-8"?>
+
+<settings xmlns='http://maven.apache.org/SETTINGS/1.0.0'>
+  <localRepository>relative/repo</localRepository>
+</settings>