Fix maximal literal string limitation in moc.

C++ standard advise to place 64k char limit for string literals, this
patch improves moc output so it is not affected anymore.

Task-number: QTBUG-36500
Change-Id: Iece630faaef45baebe8c7afe4fc51e0362c713de
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>

2 files changed, 95 insertions, 9 deletions

diff --git a/src/tools/moc/generator.cpp b/src/tools/moc/generator.cpp
index 912fa995fa..fcc43aca68 100644
--- a/src/tools/moc/generator.cpp
+++ b/src/tools/moc/generator.cpp
@@ -230,13 +230,23 @@ void Generator::generateCode()
 //
 // Build stringdata struct
 //
+    const int constCharArraySizeLimit = 65535;
     fprintf(out, "struct qt_meta_stringdata_%s_t {\n", qualifiedClassNameIdentifier.constData());
     fprintf(out, "    QByteArrayData data[%d];\n", strings.size());
     {
-        int len = 0;
-        for (int i = 0; i < strings.size(); ++i)
-            len += strings.at(i).length() + 1;
-        fprintf(out, "    char stringdata[%d];\n", len);
+        int stringDataLength = 0;
+        int stringDataCounter = 0;
+        for (int i = 0; i < strings.size(); ++i) {
+            int thisLength = strings.at(i).length() + 1;
+            stringDataLength += thisLength;
+            if (stringDataLength / constCharArraySizeLimit) {
+                // save previous stringdata and start computing the next one.
+                fprintf(out, "    char stringdata%d[%d];\n", stringDataCounter++, stringDataLength - thisLength);
+                stringDataLength = thisLength;
+            }
+        }
+        fprintf(out, "    char stringdata%d[%d];\n", stringDataCounter, stringDataLength);
+
     }
     fprintf(out, "};\n");
 
@@ -247,7 +257,7 @@ void Generator::generateCode()
     // QByteArrayData::data() implementation returning simply "this + offset".
     fprintf(out, "#define QT_MOC_LITERAL(idx, ofs, len) \\\n"
             "    Q_STATIC_BYTE_ARRAY_DATA_HEADER_INITIALIZER_WITH_OFFSET(len, \\\n"
-            "    qptrdiff(offsetof(qt_meta_stringdata_%s_t, stringdata) + ofs \\\n"
+            "    qptrdiff(offsetof(qt_meta_stringdata_%s_t, stringdata0) + ofs \\\n"
             "        - idx * sizeof(QByteArrayData)) \\\n"
             "    )\n",
             qualifiedClassNameIdentifier.constData());
@@ -282,9 +292,18 @@ void Generator::generateCode()
     fprintf(out, "    \"");
     int col = 0;
     int len = 0;
+    int stringDataLength = 0;
     for (int i = 0; i < strings.size(); ++i) {
         QByteArray s = strings.at(i);
         len = s.length();
+        stringDataLength += len + 1;
+        if (stringDataLength >= constCharArraySizeLimit) {
+            fprintf(out, "\",\n    \"");
+            stringDataLength = len + 1;
+            col = 0;
+        } else if (i)
+            fputs("\\0", out); // add \0 at the end of each string
+
         if (col && col + len >= 72) {
             fprintf(out, "\"\n    \"");
             col = 0;
@@ -309,9 +328,6 @@ void Generator::generateCode()
             idx += spanLen;
             col += spanLen;
         }
-
-        if (i != strings.size() - 1) // skip the last \0 the c++ will add it for us
-            fputs("\\0", out);
         col += len + 2;
     }
 
@@ -546,7 +562,7 @@ void Generator::generateCode()
 //
     fprintf(out, "\nvoid *%s::qt_metacast(const char *_clname)\n{\n", cdef->qualified.constData());
     fprintf(out, "    if (!_clname) return Q_NULLPTR;\n");
-    fprintf(out, "    if (!strcmp(_clname, qt_meta_stringdata_%s.stringdata))\n"
+    fprintf(out, "    if (!strcmp(_clname, qt_meta_stringdata_%s.stringdata0))\n"
                   "        return static_cast<void*>(const_cast< %s*>(this));\n",
             qualifiedClassNameIdentifier.constData(), cdef->classname.constData());
     for (int i = 1; i < cdef->superclassList.size(); ++i) { // for all superclasses but the first one
diff --git a/tests/auto/tools/moc/tst_moc.cpp b/tests/auto/tools/moc/tst_moc.cpp
index fe6ad6637a..6255082999 100644
--- a/tests/auto/tools/moc/tst_moc.cpp
+++ b/tests/auto/tools/moc/tst_moc.cpp
@@ -573,6 +573,7 @@ private slots:
     void relatedMetaObjectsNameConflict_data();
     void relatedMetaObjectsNameConflict();
     void strignLiteralsInMacroExtension();
+    void veryLongStringData();
 
 signals:
     void sigWithUnsignedArg(unsigned foo);
@@ -3309,6 +3310,75 @@ void tst_Moc::strignLiteralsInMacroExtension()
     QCOMPARE(mobj->classInfo(4).value(), "fooLiteral");
 }
 
+class VeryLongStringData : public QObject
+{
+    Q_OBJECT
+
+    #define repeat2(V) V V
+    #define repeat4(V) repeat2(V) repeat2(V)
+    #define repeat8(V) repeat4(V) repeat4(V)
+    #define repeat16(V) repeat8(V) repeat8(V)
+    #define repeat32(V) repeat16(V) repeat16(V)
+    #define repeat64(V) repeat32(V) repeat32(V)
+    #define repeat128(V) repeat64(V) repeat64(V)
+    #define repeat256(V) repeat128(V) repeat128(V)
+    #define repeat512(V) repeat256(V) repeat256(V)
+    #define repeat1024(V) repeat512(V) repeat512(V)
+    #define repeat2048(V) repeat1024(V) repeat1024(V)
+    #define repeat4096(V) repeat2048(V) repeat2048(V)
+    #define repeat8192(V) repeat4096(V) repeat4096(V)
+    #define repeat16384(V) repeat8192(V) repeat8192(V)
+    #define repeat32768(V) repeat16384(V) repeat16384(V)
+    #define repeat65534(V) repeat32768(V) repeat16384(V) repeat8192(V) repeat4096(V) repeat2048(V) repeat1024(V) repeat512(V) repeat256(V) repeat128(V) repeat64(V) repeat32(V) repeat16(V) repeat8(V) repeat4(V) repeat2(V)
+
+    Q_CLASSINFO(repeat65534("n"), repeat65534("i"))
+    Q_CLASSINFO(repeat65534("e"), repeat65534("r"))
+    Q_CLASSINFO(repeat32768("o"), repeat32768("b"))
+    Q_CLASSINFO(":", ")")
+
+    #undef repeat2
+    #undef repeat4
+    #undef repeat8
+    #undef repeat16
+    #undef repeat32
+    #undef repeat64
+    #undef repeat128
+    #undef repeat256
+    #undef repeat512
+    #undef repeat1024
+    #undef repeat2048
+    #undef repeat4096
+    #undef repeat8192
+    #undef repeat16384
+    #undef repeat32768
+    #undef repeat65534
+};
+
+void tst_Moc::veryLongStringData()
+{
+    const QMetaObject *mobj = &VeryLongStringData::staticMetaObject;
+    QCOMPARE(mobj->classInfoCount(), 4);
+
+    strlen(0);
+    QCOMPARE(mobj->classInfo(0).name()[0], 'n');
+    QCOMPARE(mobj->classInfo(0).value()[0], 'i');
+    QCOMPARE(mobj->classInfo(1).name()[0], 'e');
+    QCOMPARE(mobj->classInfo(1).value()[0], 'r');
+    QCOMPARE(mobj->classInfo(2).name()[0], 'o');
+    QCOMPARE(mobj->classInfo(2).value()[0], 'b');
+    QCOMPARE(mobj->classInfo(3).name()[0], ':');
+    QCOMPARE(mobj->classInfo(3).value()[0], ')');
+
+    QCOMPARE(strlen(mobj->classInfo(0).name()), static_cast<size_t>(65534));
+    QCOMPARE(strlen(mobj->classInfo(0).value()), static_cast<size_t>(65534));
+    QCOMPARE(strlen(mobj->classInfo(1).name()), static_cast<size_t>(65534));
+    QCOMPARE(strlen(mobj->classInfo(1).value()), static_cast<size_t>(65534));
+    QCOMPARE(strlen(mobj->classInfo(2).name()), static_cast<size_t>(32768));
+    QCOMPARE(strlen(mobj->classInfo(2).value()), static_cast<size_t>(32768));
+    QCOMPARE(strlen(mobj->classInfo(3).name()), static_cast<size_t>(1));
+    QCOMPARE(strlen(mobj->classInfo(3).value()), static_cast<size_t>(1));
+}
+
 QTEST_MAIN(tst_Moc)
 
 // the generated code must compile with QT_NO_KEYWORDS