[MNG-8018] Fix MSYS/Git-Bash path mis-detection on Windows

compat/maven-embedder/src/main/java/org/apache/maven/cli/MavenCli.java

@@ -174,6 +174,27 @@ public class MavenCli {
 
     private static final Pattern NEXT_LINE = Pattern.compile("\r?\n");
 
+    /** Matches “/d/whatever” or “/C/…”.  */
+    private static final Pattern MSYS_PATH = Pattern.compile("^/([a-zA-Z])/(.*)$");
+
+    /**
+     * Converts a POSIX-style Windows path (as used by MSYS2/Git Bash/Cygwin),
+     * e.g. "/c/Users/alice/file.txt" or "/cygdrive/c/Users/alice/file.txt",
+     * to a native Windows path "C:\Users\alice\file.txt".
+     * Returns the original string if it is already a native Windows path.
+     */
+    static String msysToWindowsPath(final String path) {
+        if (path == null) {
+            return null;
+        }
+        final Matcher matcher = MSYS_PATH.matcher(path);
+        if (matcher.matches()) {
+            return Character.toUpperCase(matcher.group(1).charAt(0)) + ":\\"
+                    + matcher.group(2).replace('/', '\\');
+        }
+        return path;
+    }
+
     public MavenCli() {
         this(null);
     }
@@ -363,6 +384,22 @@ void initialize(CliRequest cliRequest) throws ExitException {
         //
         String mavenHome = System.getProperty(Constants.MAVEN_HOME);
 
+        if (org.codehaus.plexus.util.Os.isFamily("windows")) {
+            System.setProperty("user.home", msysToWindowsPath(System.getProperty("user.home")));
+
+            for (final String key : new String[] {
+                Constants.MAVEN_REPO_LOCAL, // -Dmaven.repo.local
+                "user.settings", // -s / --settings
+                "alternateSettings",
+                "user.toolchains"
+            }) {
+                final String value = System.getProperty(key);
+                if (value != null) {
+                    System.setProperty(key, msysToWindowsPath(value));
+                }
+            }
+        }
+
         if (mavenHome != null) {
             System.setProperty(
                     Constants.MAVEN_HOME,

compat/maven-embedder/src/test/java/org/apache/maven/cli/MavenCliTest.java

@@ -28,6 +28,7 @@
 import java.nio.file.Paths;
 import java.util.Collections;
 import java.util.List;
+import java.util.Properties;
 import java.util.stream.Stream;
 
 import com.google.common.jimfs.Configuration;
@@ -60,6 +61,9 @@
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.condition.EnabledOnOs;
+import org.junit.jupiter.api.condition.OS;
+import org.junit.jupiter.api.io.TempDir;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.Arguments;
 import org.junit.jupiter.params.provider.MethodSource;
@@ -702,6 +706,50 @@ public void calculateTransferListener(boolean ciEnv, String[] cliArgs, Class<Tra
         assertThat(transferListener.getClass(), is(expectedSubClass));
     }
 
+    /**
+     * “/d/…” and “/c/…” should convert to proper Windows drive paths.
+     */
+    @Test
+    void msysPathsAreConverted() {
+        assertEquals(
+                "D:/projects/foo", MavenCli.msysToWindowsPath("/d/projects/foo").replace('\\', '/'));
+        assertEquals("C:/x", MavenCli.msysToWindowsPath("/c/x").replace('\\', '/'));
+    }
+
+    /**
+     * Full `initialize` run: ensures the JVM properties are rewritten when running on Windows.
+     */
+    @Test
+    @EnabledOnOs(OS.WINDOWS)
+    void initializeNormalisesUserHome(@TempDir Path tmpDir) throws Exception {
+        // Backup current system properties to restore afterwards
+        final Properties backup = (Properties) System.getProperties().clone();
+        try {
+            // Pretend we are on Windows so Os.isFamily("windows") returns true
+            System.setProperty("os.name", "Windows 10");
+
+            // Required by MavenCli.initialize
+            System.setProperty(MavenCli.MULTIMODULE_PROJECT_DIRECTORY, tmpDir.toString());
+
+            // Inject MSYS‑style paths
+            System.setProperty("user.home", "/d/test/home");
+            System.setProperty(Constants.MAVEN_REPO_LOCAL, "/d/test/repo");
+
+            final MavenCli cli = new MavenCli();
+            final CliRequest req = new CliRequest(new String[0], null);
+            cli.initialize(req);
+
+            // Assertions: both properties should now be real Windows paths
+            assertEquals("D:/test/home", System.getProperty("user.home").replace('\\', '/'));
+            assertEquals(
+                    "D:/test/repo",
+                    System.getProperty(Constants.MAVEN_REPO_LOCAL).replace('\\', '/'));
+        } finally {
+            // Restore original system properties
+            System.setProperties(backup);
+        }
+    }
+
     public static Stream<Arguments> calculateTransferListenerArguments() {
         return Stream.of(
                 Arguments.of(false, new String[] {}, ConsoleMavenTransferListener.class),

impl/maven-cli/src/main/java/org/apache/maven/cling/invoker/LookupInvoker.java

@@ -120,6 +120,17 @@ public final int invoke(InvokerRequest invokerRequest) {
         oldProps.putAll(System.getProperties());
         ClassLoader oldCL = Thread.currentThread().getContextClassLoader();
         try (C context = createContext(invokerRequest)) {
+            // Normalize user.home for Git Bash-style paths on Windows
+            if (isWindows()) {
+                String userHome = System.getProperty("user.home");
+                if (userHome != null && userHome.startsWith("/")) {
+                    final String normalizedUserHome = normalizeMsysPath(userHome, context);
+                    if (normalizedUserHome != null) {
+                        System.setProperty("user.home", normalizedUserHome);
+                        context.logger.debug("Normalized user.home '" + userHome + "' to '" + normalizedUserHome + "'");
+                    }
+                }
+            }
             if (contextConsumer != null) {
                 contextConsumer.accept(context);
             }
@@ -736,7 +747,9 @@ protected Path localRepositoryPath(C context) {
             }
         }
         if (userDefinedLocalRepo != null) {
-            return context.cwd.resolve(userDefinedLocalRepo);
+            // Normalize MSYS-style paths on Windows
+            final String normalizedPath = normalizeMsysPath(userDefinedLocalRepo, context);
+            return context.cwd.resolve(normalizedPath);
         }
         // settings
         userDefinedLocalRepo = context.effectiveSettings.getLocalRepository();
@@ -918,6 +931,29 @@ protected int calculateDegreeOfConcurrency(String threadConfiguration) {
                     + "'. Supported are int and float values ending with C.");
         }
     }
+    // Helper method to normalize MSYS-style paths on Windows
+    private String normalizeMsysPath(String path, C context) {
+        if (path != null && isWindows() && path.startsWith("/")) {
+            try {
+                // Convert /d/path to D:\path
+                final String drive = path.substring(1, 2).toUpperCase(Locale.ENGLISH);
+                final String rest = path.substring(2).replace("/", "\\");
+                final String normalized = drive + ":" + rest;
+                context.logger.debug("Normalized MSYS path '" + path + "' to '" + normalized + "'");
+                System.out.println("Normalized MSYS path '" + path + "' to '" + normalized + "'");
+                return normalized;
+            } catch (final Exception e) {
+                context.logger.warn("Failed to normalize MSYS path '" + path + "': " + e.getMessage());
+                return path;
+            }
+        }
+        return path;
+    }
+
+    // Helper method to check if running on Windows
+    private boolean isWindows() {
+        return System.getProperty("os.name").toLowerCase(Locale.ENGLISH).contains("win");
+    }
 
     protected abstract int execute(C context) throws Exception;
 }

impl/maven-cli/src/test/java/org/apache/maven/cling/invoker/mvn/MavenInvokerTest.java

@@ -34,6 +34,8 @@
 import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.Order;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.condition.EnabledOnOs;
+import org.junit.jupiter.api.condition.OS;
 import org.junit.jupiter.api.io.CleanupMode;
 import org.junit.jupiter.api.io.TempDir;
 
@@ -233,4 +235,63 @@ void jimFs() throws Exception {
             invoke(fs.getPath("/cwd"), fs.getPath("/home"), List.of("verify"), List.of());
         }
     }
+
+    @Test
+    @EnabledOnOs(OS.WINDOWS)
+    void msysRepoPathIsNormalised(@TempDir Path tmp) throws Exception {
+
+        final Path cwd = tmp.resolve("project");
+        final Path userHome = tmp.resolve("userHome");
+        Files.createDirectories(cwd);
+        Files.createDirectories(userHome.resolve(".m2"));
+
+        /* ---------- PATCH: write minimal, well-formed toolchains.xml ---------- */
+        Files.writeString(
+                userHome.resolve(".m2/toolchains.xml"),
+                """
+            <?xml version="1.0" encoding="UTF-8"?>
+            <toolchains xmlns="http://maven.apache.org/TOOLCHAINS/1.1.0"
+                        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+                        xsi:schemaLocation="http://maven.apache.org/TOOLCHAINS/1.1.0 https://maven.apache.org/xsd/toolchains-1.1.0.xsd">
+            </toolchains>
+            """);
+
+        /* minimal POM so Maven has something to parse */
+        Files.writeString(
+                cwd.resolve("pom.xml"),
+                """
+            <?xml version="1.0" encoding="UTF-8"?>
+            <project xmlns="http://maven.apache.org/POM/4.0.0"
+                     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+                     xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+                <modelVersion>4.0.0</modelVersion>
+                <groupId>org.apache.maven.samples</groupId>
+                <artifactId>sample</artifactId>
+                <version>1.0-SNAPSHOT</version>
+            </project>
+            """);
+
+        /* pretend we are on Windows so the normaliser runs */
+        final String origOs = System.getProperty("os.name");
+        System.setProperty("os.name", "Windows 10");
+        try {
+            final List<String> args = List.of("-Dmaven.repo.local=/c/projects/mmm/conf/.m2/repository");
+            final List<String> goals = List.of("validate");
+
+            final Map<String, String> logs = invoke(cwd, userHome, goals, args);
+            final String log = String.join("", logs.values());
+
+            /* no doubled-drive repository attempt */
+            assertFalse(
+                    log.contains("\\c\\projects") || log.contains("\\d\\projects"),
+                    "Maven still tried to use a doubled-drive path:\n" + log);
+
+        } finally {
+            if (origOs == null) {
+                System.clearProperty("os.name");
+            } else {
+                System.setProperty("os.name", origOs);
+            }
+        }
+    }
 }