qmltc: export generated classes

Add QMLTC_EXPORT_MACRO_NAME and QMLTC_EXPORT_FILE_NAME arguments to
qt_add_qml_module() that allows the user to export qmltc-generated code
from its library. The qmltc-generated code will include the header-file
specified in QMLTC_EXPORT_FILE_NAME and will be exported with the macro
specified by QMLTC_EXPORT_MACRO_NAME.
Leave both options unspecified to not export the code generated by
qmltc.

Describe the options in the documentation and write a test to see if the
class really has an export macro in the generated code:
1) tst_qmltc_qprocess will test if the macro and the header are correctly
inserted in the generated code.
2) tst_qmltc_{no,}diskcache will test if the generated code can still be
   used from a static library.

Fixes: QTBUG-106840
Task-number: QTBUG-96040
Change-Id: I554f03bcdf043e8114e42f51a7289a5c00de4f89
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

14 files changed, 160 insertions, 11 deletions

diff --git a/src/qml/Qt6QmlMacros.cmake b/src/qml/Qt6QmlMacros.cmake
index 6b3e8ffb08..70f33d0749 100644
--- a/src/qml/Qt6QmlMacros.cmake
+++ b/src/qml/Qt6QmlMacros.cmake
@@ -58,6 +58,8 @@ function(qt6_add_qml_module target)
         INSTALL_DIRECTORY
         INSTALL_LOCATION
         TYPE_COMPILER_NAMESPACE
+        QMLTC_EXPORT_DIRECTIVE
+        QMLTC_EXPORT_FILE_NAME
     )
 
     set(args_multi
@@ -147,11 +149,32 @@ function(qt6_add_qml_module target)
             )
     endif()
 
-    if (DEFINED arg_TYPE_COMPILER_NAMESPACE AND NOT arg_ENABLE_TYPE_COMPILER)
-        message(WARNING
-            "TYPE_COMPILER_NAMESPACE is set, but ENABLE_TYPE_COMPILER is not specified. "
-            "The TYPE_COMPILER_NAMESPACE value will be ignored."
-        )
+    if (NOT arg_ENABLE_TYPE_COMPILER)
+        if (DEFINED arg_TYPE_COMPILER_NAMESPACE)
+            message(WARNING
+                "TYPE_COMPILER_NAMESPACE is set, but ENABLE_TYPE_COMPILER is not specified. "
+                "The TYPE_COMPILER_NAMESPACE value will be ignored."
+            )
+        endif()
+
+        if (DEFINED arg_QMLTC_EXPORT_DIRECTIVE)
+            message(WARNING
+                "QMLTC_EXPORT_DIRECTIVE is set, but ENABLE_TYPE_COMPILER is not specified. "
+                "The QMLTC_EXPORT_DIRECTIVE value will be ignored."
+            )
+        endif()
+        if (DEFINED arg_QMLTC_EXPORT_FILE_NAME)
+            message(WARNING
+                "QMLTC_EXPORT_FILE_NAME is set, but ENABLE_TYPE_COMPILER is not specified. "
+                "The QMLTC_EXPORT_FILE_NAME will be ignored."
+            )
+        endif()
+    else()
+        if ((DEFINED arg_QMLTC_EXPORT_FILE_NAME) AND (NOT (DEFINED arg_QMLTC_EXPORT_DIRECTIVE)))
+            message(FATAL_ERROR
+                "Specifying a value for QMLTC_EXPORT_FILE_NAME also requires one for QMLTC_EXPORT_DIRECTIVE."
+            )
+        endif()
     endif()
 
     set(is_executable FALSE)
@@ -670,6 +693,8 @@ Check https://doc.qt.io/qt-6/qt-cmake-policy-qtp0001.html for policy details."
             QML_FILES ${arg_QML_FILES}
             IMPORT_PATHS ${arg_IMPORT_PATH}
             NAMESPACE ${qmltc_namespace}
+            EXPORT_MACRO_NAME ${arg_QMLTC_EXPORT_DIRECTIVE}
+            EXPORT_FILE_NAME ${arg_QMLTC_EXPORT_FILE_NAME}
         )
     endif()
 
@@ -1243,7 +1268,7 @@ endfunction()
 # Compile Qml files (.qml) to C++ source files with Qml Type Compiler (qmltc).
 function(_qt_internal_target_enable_qmltc target)
     set(args_option "")
-    set(args_single NAMESPACE)
+    set(args_single NAMESPACE EXPORT_MACRO_NAME EXPORT_FILE_NAME)
     set(args_multi QML_FILES IMPORT_PATHS)
 
     cmake_parse_arguments(PARSE_ARGV 1 arg
@@ -1276,6 +1301,10 @@ function(_qt_internal_target_enable_qmltc target)
     if(arg_NAMESPACE)
         list(APPEND common_args --namespace "${arg_NAMESPACE}")
     endif()
+    if(arg_EXPORT_MACRO_NAME)
+        list(APPEND common_args --export "${arg_EXPORT_MACRO_NAME}")
+        list(APPEND common_args --exportInclude "${arg_EXPORT_FILE_NAME}")
+    endif()
 
     get_target_property(output_dir ${target} QT_QML_MODULE_OUTPUT_DIRECTORY)
     set(qmldir_file ${output_dir}/qmldir)
diff --git a/src/qml/doc/src/cmake/qt_add_qml_module.qdoc b/src/qml/doc/src/cmake/qt_add_qml_module.qdoc
index 857779af2d..e7572163f0 100644
--- a/src/qml/doc/src/cmake/qt_add_qml_module.qdoc
+++ b/src/qml/doc/src/cmake/qt_add_qml_module.qdoc
@@ -50,6 +50,9 @@ qt_add_qml_module(
     [NO_IMPORT_SCAN]
     [ENABLE_TYPE_COMPILER]
     [TYPE_COMPILER_NAMESPACE namespace]
+    [QMLTC_EXPORT_DIRECTIVE export_macro]
+    [QMLTC_EXPORT_FILE_NAME header_defining_export_macro]
+
 )
 
 \endcode
@@ -691,4 +694,15 @@ can be put instead in a custom namespace, where different subnamespaces are to
 be separated by a "::", e.g. "MyNamespace::MySubnamespace" for the namespace MySubnamespace that
 is inside the MyNamespace. Apart from the "::", C++ namespace naming rules
 apply.
+
+\c QMLTC_QMLTC_EXPORT_DIRECTIVE should be used with \c QMLTC_EXPORT_FILE_NAME when
+the classes generated by \l{QML Type Compiler}{qmltc} should be exported from
+the qml library. By default, classes generated by qmltc are not exported from
+their library.
+The header defining the export macro for the current library
+can be specified as an optional argument to \c QMLTC_EXPORT_FILE_NAME while the
+exporting macro name should be specified as an argument to
+\c QMLTC_QMLTC_EXPORT_DIRECTIVE. If no additional include is required or wanted,
+e.g. when the header of the export macro is already indirectly included by a base
+class, then the \c QMLTC_EXPORT_FILE_NAME option can be left out.
 */
diff --git a/tests/auto/qml/qmltc/CMakeLists.txt b/tests/auto/qml/qmltc/CMakeLists.txt
index 4b86a6c018..1b7fbf6ee1 100644
--- a/tests/auto/qml/qmltc/CMakeLists.txt
+++ b/tests/auto/qml/qmltc/CMakeLists.txt
@@ -3,6 +3,7 @@
 
 add_subdirectory(QmltcTests)
 add_subdirectory(NamespaceTest/Subfolder)
+add_subdirectory(QmltcExportedTests)
 
 set(test_sources
     nameconflict.h nameconflict.cpp
@@ -18,6 +19,8 @@ set(qmltc_module_libs
     #   automatic type registration that comes from the plugin)
     qmltc_test_moduleplugin
     qmltc_namespace_test_module
+    qmltc_exported_tests_module
+    qmltc_exported_tests_moduleplugin
 )
 qt_internal_add_test(tst_qmltc_diskcache
     SOURCES ${test_sources}
diff --git a/tests/auto/qml/qmltc/QmltcExportedTests/CMakeLists.txt b/tests/auto/qml/qmltc/QmltcExportedTests/CMakeLists.txt
new file mode 100644
index 0000000000..1e1454baff
--- /dev/null
+++ b/tests/auto/qml/qmltc/QmltcExportedTests/CMakeLists.txt
@@ -0,0 +1,30 @@
+# Copyright (C) 2023 The Qt Company Ltd.
+# SPDX-License-Identifier: BSD-3-Clause
+
+qt_add_library(qmltc_exported_tests_module STATIC)
+qt_autogen_tools_initial_setup(qmltc_exported_tests_module)
+
+include(GenerateExportHeader)
+generate_export_header(qmltc_exported_tests_module)
+
+set(common_libraries
+    Qt::QuickPrivate
+)
+
+target_link_libraries(qmltc_exported_tests_module PUBLIC ${common_libraries})
+
+qt6_add_qml_module(qmltc_exported_tests_module
+    URI QmltcExportedTests
+    AUTO_RESOURCE_PREFIX
+    QML_FILES
+        HelloExportedWorld.qml
+    DEPENDENCIES
+        Qt::Quick
+    ENABLE_TYPE_COMPILER
+    QMLTC_EXPORT_DIRECTIVE "QMLTC_EXPORTED_TESTS_MODULE_EXPORT"
+    QMLTC_EXPORT_FILE_NAME "qmltc_exported_tests_module_export.h"
+)
+
+target_include_directories(qmltc_exported_tests_module PUBLIC ${CMAKE_CURRENT_BINARY_DIR} ${CMAKE_CURRENT_SOURCE_DIR})
+
+qt_autogen_tools_initial_setup(qmltc_exported_tests_moduleplugin)
diff --git a/tests/auto/qml/qmltc/QmltcExportedTests/HelloExportedWorld.qml b/tests/auto/qml/qmltc/QmltcExportedTests/HelloExportedWorld.qml
new file mode 100644
index 0000000000..5e6886bced
--- /dev/null
+++ b/tests/auto/qml/qmltc/QmltcExportedTests/HelloExportedWorld.qml
@@ -0,0 +1,5 @@
+import QtQuick
+
+Item {
+    property string myString: "Hello! I should be exported by qmltc"
+}
diff --git a/tests/auto/qml/qmltc/tst_qmltc.cpp b/tests/auto/qml/qmltc/tst_qmltc.cpp
index 1fa4030642..381701991e 100644
--- a/tests/auto/qml/qmltc/tst_qmltc.cpp
+++ b/tests/auto/qml/qmltc/tst_qmltc.cpp
@@ -77,6 +77,7 @@
 #include "repeatercrash.h"
 #include "aliases.h"
 #include "inlinecomponentsfromdifferentfiles.h"
+#include "helloexportedworld.h"
 
 #include "testprivateproperty.h"
 #include "singletons.h"
@@ -3208,4 +3209,11 @@ void tst_qmltc::namespacedName()
     Q_UNUSED(t);
 }
 
+void tst_qmltc::checkExportsAreCompiling()
+{
+    QQmlEngine e;
+    QmltcExportedTests::HelloExportedWorld w(&e);
+    QCOMPARE(w.myString(), u"Hello! I should be exported by qmltc"_s);
+}
+
 QTEST_MAIN(tst_qmltc)
diff --git a/tests/auto/qml/qmltc/tst_qmltc.h b/tests/auto/qml/qmltc/tst_qmltc.h
index af084dcc01..f00a172522 100644
--- a/tests/auto/qml/qmltc/tst_qmltc.h
+++ b/tests/auto/qml/qmltc/tst_qmltc.h
@@ -93,4 +93,5 @@ private slots:
     void constSignalParameters();
     void cppNamespaces();
     void namespacedName();
+    void checkExportsAreCompiling();
 };
diff --git a/tests/auto/qml/qmltc_qprocess/tst_qmltc_qprocess.cpp b/tests/auto/qml/qmltc_qprocess/tst_qmltc_qprocess.cpp
index 7f12f29342..f0b99fcdf0 100644
--- a/tests/auto/qml/qmltc_qprocess/tst_qmltc_qprocess.cpp
+++ b/tests/auto/qml/qmltc_qprocess/tst_qmltc_qprocess.cpp
@@ -51,6 +51,7 @@ private slots:
     void topLevelComponent();
     void dashesInFilename();
     void invalidSignalHandlers();
+    void exports();
 };
 
 #ifndef TST_QMLTC_QPROCESS_RESOURCES
@@ -261,5 +262,38 @@ void tst_qmltc_qprocess::invalidSignalHandlers()
     }
 }
 
+static QString fileToString(const QString &path)
+{
+    QFile f(path);
+    if (f.open(QIODevice::ReadOnly))
+        return QString::fromLatin1(f.readAll());
+    return QString();
+}
+
+void tst_qmltc_qprocess::exports()
+{
+    const QString fileName = u"dummy.qml"_s;
+    QStringList extraArgs;
+    extraArgs << "--export"
+              << "MYLIB_EXPORT_MACRO"
+              << "--exportInclude"
+              << "exportheader.h";
+    const auto errors = runQmltc(fileName, true, extraArgs);
+
+    const QString headerName = m_tmpPath + u"/"_s + QFileInfo(fileName).baseName() + u".h"_s;
+    const QString header = fileToString(headerName);
+    const QString implementationName =
+            m_tmpPath + u"/"_s + QFileInfo(fileName).baseName() + u".cpp"_s;
+    const QString implementation = fileToString(implementationName);
+
+    QCOMPARE(errors.size(), 0);
+
+    QVERIFY(header.contains(u"class MYLIB_EXPORT_MACRO dummy : public QObject\n"_s));
+    QVERIFY(!implementation.contains(u"MYLIB_EXPORT_MACRO"_s));
+
+    QVERIFY(header.contains(u"#include \"exportheader.h\"\n"_s));
+    QVERIFY(!implementation.contains(u"exportheader.h"_s));
+}
+
 QTEST_MAIN(tst_qmltc_qprocess)
 #include "tst_qmltc_qprocess.moc"
diff --git a/tools/qmltc/main.cpp b/tools/qmltc/main.cpp
index 6ef0afe105..65560c70e1 100644
--- a/tools/qmltc/main.cpp
+++ b/tools/qmltc/main.cpp
@@ -99,6 +99,18 @@ int main(int argc, char **argv)
         QCoreApplication::translate("main", "namespace")
     };
     parser.addOption(namespaceOption);
+    QCommandLineOption exportOption{ u"export"_s,
+                                     QCoreApplication::translate(
+                                             "main", "Export macro used in the generated C++ code"),
+                                     QCoreApplication::translate("main", "export") };
+    parser.addOption(exportOption);
+    QCommandLineOption exportIncludeOption{
+        u"exportInclude"_s,
+        QCoreApplication::translate(
+                "main", "Header defining the export macro to be used in the generated C++ code"),
+        QCoreApplication::translate("main", "exportInclude")
+    };
+    parser.addOption(exportIncludeOption);
 
     parser.process(app);
 
@@ -224,6 +236,8 @@ int main(int argc, char **argv)
     info.outputHFile = parser.value(outputHOption);
     info.resourcePath = firstQml(paths);
     info.outputNamespace = parser.value(namespaceOption);
+    info.exportMacro = parser.value(exportOption);
+    info.exportInclude = parser.value(exportIncludeOption);
 
     if (info.outputCppFile.isEmpty()) {
         fprintf(stderr, "An output C++ file is required. Pass one using --impl");
diff --git a/tools/qmltc/qmltccodewriter.cpp b/tools/qmltc/qmltccodewriter.cpp
index 8010f1066c..6996277473 100644
--- a/tools/qmltc/qmltccodewriter.cpp
+++ b/tools/qmltc/qmltccodewriter.cpp
@@ -209,7 +209,7 @@ void QmltcCodeWriter::write(QmltcOutputWrapper &code, const QmltcProgram &progra
         code.rawAppendToHeader(u"class " + type.cppType + u";");
     // write all the types and their content
     for (const QmltcType &type : std::as_const(program.compiledTypes))
-        write(code, type);
+        write(code, type, program.exportMacro);
 
     // add typeCount definitions. after all types have been written down (so
     // they are now complete types as per C++). practically, this only concerns
@@ -251,10 +251,14 @@ static void dumpFunctions(QmltcOutputWrapper &code, const QList<QmltcMethod> &fu
     }
 }
 
-void QmltcCodeWriter::write(QmltcOutputWrapper &code, const QmltcType &type)
+void QmltcCodeWriter::write(QmltcOutputWrapper &code, const QmltcType &type,
+                            const QString &exportMacro)
 {
     const auto constructClassString = [&]() {
-        QString str = u"class " + type.cppType;
+        QString str = u"class "_s;
+        if (!exportMacro.isEmpty())
+            str.append(exportMacro).append(u" "_s);
+        str.append(type.cppType);
         QStringList nonEmptyBaseClasses;
         nonEmptyBaseClasses.reserve(type.baseClasses.size());
         std::copy_if(type.baseClasses.cbegin(), type.baseClasses.cend(),
@@ -340,7 +344,7 @@ void QmltcCodeWriter::write(QmltcOutputWrapper &code, const QmltcType &type)
 
         // children
         for (const auto &child : std::as_const(type.children))
-            QmltcCodeWriter::write(code, child);
+            QmltcCodeWriter::write(code, child, exportMacro);
 
         // (non-visible) functions
         dumpFunctions(code, type.functions, std::not_fn(isUserVisibleFunction));
diff --git a/tools/qmltc/qmltccodewriter.h b/tools/qmltc/qmltccodewriter.h
index e95777998e..04446f4c4e 100644
--- a/tools/qmltc/qmltccodewriter.h
+++ b/tools/qmltc/qmltccodewriter.h
@@ -20,7 +20,7 @@ struct QmltcCodeWriter
     static void writeGlobalFooter(QmltcOutputWrapper &code, const QString &sourcePath,
                                   const QString &outNamespace);
     static void write(QmltcOutputWrapper &code, const QmltcProgram &program);
-    static void write(QmltcOutputWrapper &code, const QmltcType &type);
+    static void write(QmltcOutputWrapper &code, const QmltcType &type, const QString &exportMacro);
     static void write(QmltcOutputWrapper &code, const QmltcEnum &enumeration);
     static void write(QmltcOutputWrapper &code, const QmltcMethod &method);
     static void write(QmltcOutputWrapper &code, const QmltcCtor &ctor);
diff --git a/tools/qmltc/qmltccompiler.cpp b/tools/qmltc/qmltccompiler.cpp
index 4050136ef2..d97fc26ecf 100644
--- a/tools/qmltc/qmltccompiler.cpp
+++ b/tools/qmltc/qmltccompiler.cpp
@@ -142,8 +142,11 @@ void QmltcCompiler::compile(const QmltcCompilerInfo &info)
     program.cppPath = m_info.outputCppFile;
     program.hPath = m_info.outputHFile;
     program.outNamespace = m_info.outputNamespace;
+    program.exportMacro = m_info.exportMacro;
     program.compiledTypes = compiledTypes;
     program.includes = m_visitor->cppIncludeFiles();
+    if (!m_info.exportMacro.isEmpty() && !m_info.exportInclude.isEmpty())
+        program.includes += (m_info.exportInclude);
     program.urlMethod = urlMethod;
 
     QmltcOutput out;
diff --git a/tools/qmltc/qmltccompiler.h b/tools/qmltc/qmltccompiler.h
index d5f07aa3b0..baa5b23256 100644
--- a/tools/qmltc/qmltccompiler.h
+++ b/tools/qmltc/qmltccompiler.h
@@ -25,6 +25,8 @@ struct QmltcCompilerInfo
     QString outputHFile;
     QString outputNamespace;
     QString resourcePath;
+    QString exportMacro;
+    QString exportInclude;
 };
 
 class QmltcCompiler
diff --git a/tools/qmltc/qmltcoutputir.h b/tools/qmltc/qmltcoutputir.h
index 8884ddc3a3..cd094ee7b1 100644
--- a/tools/qmltc/qmltcoutputir.h
+++ b/tools/qmltc/qmltcoutputir.h
@@ -140,6 +140,8 @@ struct QmltcProgram
     QString cppPath; // C++ output .cpp path
     QString hPath; // C++ output .h path
     QString outNamespace;
+    QString exportMacro; // if not empty, the macro that should be used to export the generated
+                         // classes
     QSet<QString> includes; // non-default C++ include files
     QmltcMethod urlMethod; // returns QUrl of the QML document