Fix buildCodegenCLI on Windows

packages/gradle-plugin/react-native-gradle-plugin/src/main/kotlin/com/facebook/react/tasks/internal/BuildCodegenCLITask.kt

@@ -8,6 +8,7 @@
 package com.facebook.react.tasks.internal
 
 import com.facebook.react.utils.Os.unixifyPath
+import com.facebook.react.utils.findGitBashOnWindows
 import com.facebook.react.utils.windowsAwareBashCommandLine
 import java.io.FileOutputStream
 import org.gradle.api.file.DirectoryProperty
@@ -53,7 +54,7 @@ abstract class BuildCodegenCLITask : Exec() {
     commandLine(
         windowsAwareBashCommandLine(
             codegenDir.asFile.get().canonicalPath.unixifyPath().plus(BUILD_SCRIPT_PATH),
-            bashWindowsHome = bashWindowsHome.orNull,
+            bashWindowsHome = bashWindowsHome.orNull ?: findGitBashOnWindows(),
         ),
     )
     super.exec()

packages/gradle-plugin/shared/src/main/kotlin/com/facebook/react/utils/TaskUtils.kt

@@ -7,6 +7,8 @@
 
 package com.facebook.react.utils
 
+import java.io.File
+
 fun windowsAwareCommandLine(vararg args: Any): List<Any> = windowsAwareCommandLine(args.toList())
 
 fun windowsAwareCommandLine(args: List<Any>): List<Any> =
@@ -25,3 +27,27 @@ fun windowsAwareBashCommandLine(
     } else {
       args.toList()
     }
+
+/**
+ * Returns `<root>\bin\bash.exe` for the first `<root>\<folder>\git.exe` on the PATH that has one,
+ * or null. This is where Git for Windows keeps its bash.
+ *
+ * A bare `bash` is not reliable on Windows: the Git installer adds only `<git>\cmd` to the PATH by
+ * default, and when WSL is installed `bash` resolves to the WSL launcher in `System32`, which
+ * Windows searches before the PATH.
+ */
+fun findGitBashOnWindows(path: String? = System.getenv("PATH")): String? {
+  if (!Os.isWindows() || path == null) {
+    return null
+  }
+  return path
+      .split(File.pathSeparatorChar)
+      .asSequence()
+      .map { it.trim().removeSurrounding("\"") }
+      .filter { it.isNotEmpty() }
+      .map { File(it, "git.exe") }
+      .filter { it.isFile }
+      .mapNotNull { it.absoluteFile.parentFile?.parentFile?.resolve("bin/bash.exe") }
+      .firstOrNull { it.isFile }
+      ?.absolutePath
+}

packages/gradle-plugin/shared/src/test/kotlin/com/facebook/react/utils/TaskUtilsTest.kt

@@ -10,14 +10,18 @@ package com.facebook.react.utils
 import com.facebook.react.tests.OS
 import com.facebook.react.tests.OsRule
 import com.facebook.react.tests.WithOs
+import java.io.File
 import org.assertj.core.api.Assertions.assertThat
 import org.junit.Rule
 import org.junit.Test
+import org.junit.rules.TemporaryFolder
 
 class TaskUtilsTest {
 
   @get:Rule val osRule = OsRule()
 
+  @get:Rule val tempFolder = TemporaryFolder()
+
   @Test
   fun windowsAwareCommandLine_withEmptyInput_isEmpty() {
     assertThat(windowsAwareCommandLine().isEmpty()).isTrue()
@@ -73,4 +77,66 @@ class TaskUtilsTest {
     assertThat(listOf("/custom/bash", "-c", "a", "b", "c"))
         .isEqualTo(windowsAwareBashCommandLine("a", "b", "c", bashWindowsHome = "/custom/bash"))
   }
+
+  @Test
+  @WithOs(OS.WIN)
+  fun findGitBashOnWindows_withGitOnPath_returnsBashOfThatInstall() {
+    val gitRoot = createGitInstall("Git")
+
+    assertThat(findGitBashOnWindows(File(gitRoot, "cmd").absolutePath))
+        .isEqualTo(File(gitRoot, "bin/bash.exe").absolutePath)
+  }
+
+  @Test
+  @WithOs(OS.WIN)
+  fun findGitBashOnWindows_skipsGitWithoutBashNextToIt() {
+    val gitWithoutBash = tempFolder.newFolder("mingw64", "bin")
+    File(gitWithoutBash, "git.exe").createNewFile()
+    val gitRoot = createGitInstall("Git")
+    val path =
+        listOf(gitWithoutBash.absolutePath, File(gitRoot, "cmd").absolutePath)
+            .joinToString(File.pathSeparator)
+
+    assertThat(findGitBashOnWindows(path)).isEqualTo(File(gitRoot, "bin/bash.exe").absolutePath)
+  }
+
+  @Test
+  @WithOs(OS.WIN)
+  fun findGitBashOnWindows_withoutGitOnPath_returnsNull() {
+    assertThat(findGitBashOnWindows(tempFolder.newFolder("empty").absolutePath)).isNull()
+  }
+
+  @Test
+  @WithOs(OS.WIN)
+  fun findGitBashOnWindows_withBashButNoGitOnPath_returnsNull() {
+    val toolsRoot = tempFolder.newFolder("tools")
+    File(toolsRoot, "cmd").mkdirs()
+    File(toolsRoot, "bin").mkdirs()
+    File(toolsRoot, "bin/bash.exe").createNewFile()
+
+    assertThat(findGitBashOnWindows(File(toolsRoot, "cmd").absolutePath)).isNull()
+  }
+
+  @Test
+  @WithOs(OS.WIN)
+  fun findGitBashOnWindows_withNullPath_returnsNull() {
+    assertThat(findGitBashOnWindows(null)).isNull()
+  }
+
+  @Test
+  @WithOs(OS.LINUX)
+  fun findGitBashOnWindows_onLinux_returnsNull() {
+    val gitRoot = createGitInstall("Git")
+
+    assertThat(findGitBashOnWindows(File(gitRoot, "cmd").absolutePath)).isNull()
+  }
+
+  private fun createGitInstall(name: String): File {
+    val gitRoot = tempFolder.newFolder(name)
+    File(gitRoot, "cmd").mkdirs()
+    File(gitRoot, "cmd/git.exe").createNewFile()
+    File(gitRoot, "bin").mkdirs()
+    File(gitRoot, "bin/bash.exe").createNewFile()
+    return gitRoot
+  }
 }

packages/react-native-codegen/scripts/oss/build.sh

@@ -64,7 +64,7 @@ else
   # during recursive copying, and `rsync` is not installed by default in Git Bash.
   # As an added benefit, blob copy is faster.
   if [ "$OSTYPE" = "msys" ] || [ "$OSTYPE" = "cygwin" ]; then
-    tar cf - --exclude='*.lock' "$CODEGEN_DIR" | (cd "$TMP_DIR" && tar xvf - );
+    tar cf - --exclude='*.lock' -C "$CODEGEN_DIR" . | (cd "$TMP_DIR" && tar xvf - );
   else
     /bin/cp -R "$CODEGEN_DIR/." "$TMP_DIR";
   fi

packages/react-native/ReactAndroid/build.gradle.kts

@@ -484,7 +484,7 @@ val prepareKotlinBuildScriptModel by
 val buildCodegenCLI by
     tasks.registering(BuildCodegenCLITask::class) {
       codegenDir.set(file("$rootDir/node_modules/@react-native/codegen"))
-      bashWindowsHome.set(project.findProperty("react.internal.windowsBashPath").toString())
+      bashWindowsHome.set(project.findProperty("react.internal.windowsBashPath")?.toString())
       logFile.set(file("$buildDir/codegen.log"))
       inputFiles.set(fileTree(codegenDir) { include("src/**/*.js") })
       outputFiles.set(