Android: warn about too long build paths on Windows

If Gradle build fails on Windows, check for java files that exceed
the max length of 260 that Gradle can handle, then warn about the length
issue.

Pick-to: 5.15
Task-number: QTBUG-83875
Change-Id: Ia7462bc816b3efa4ba9fdd0f179fdc4c06e23248
Reviewed-by: Andy Shaw <andy.shaw@qt.io>

src/tools/androiddeployqt/main.cpp

@@ -44,6 +44,10 @@
 
 #include <algorithm>
 
+#if defined(Q_OS_WIN32)
+#include <qt_windows.h>
+#endif
+
 #ifdef Q_CC_MSVC
 #define popen _popen
 #define QT_POPEN_READ "rb"
@@ -2326,6 +2330,27 @@ static bool mergeGradleProperties(const QString &path, GradleProperties properti
     return true;
 }
 
+#if defined(Q_OS_WIN32)
+void checkAndWarnGradleLongPaths(const QString &outputDirectory)
+{
+    QStringList longFileNames;
+    QDirIterator it(outputDirectory, QStringList(QStringLiteral("*.java")), QDir::Files,
+                    QDirIterator::Subdirectories);
+    while (it.hasNext()) {
+        if (it.next().size() >= MAX_PATH)
+            longFileNames.append(it.next());
+    }
+
+    if (!longFileNames.isEmpty()) {
+        fprintf(stderr,
+                "The maximum path length that can be processed by Gradle on Windows is %d characters.\n"
+                "Consider moving your project to reduce its path length.\n"
+                "The following files have too long paths:\n%s.\n",
+                MAX_PATH, qPrintable(longFileNames.join(QLatin1Char('\n'))));
+    }
+}
+#endif
+
 bool buildAndroidProject(const Options &options)
 {
     GradleProperties localProperties;
@@ -2390,6 +2415,10 @@ bool buildAndroidProject(const Options &options)
         fprintf(stderr, "Building the android package failed!\n");
         if (!options.verbose)
             fprintf(stderr, "  -- For more information, run this command with --verbose.\n");
+
+#if defined(Q_OS_WIN32)
+        checkAndWarnGradleLongPaths(options.outputDirectory);
+#endif
         return false;
     }