tracegen: Add common prologue

Add common prologue and add error message when tracing is used in a
module that doesn't have Q_TRACEPOINT enabled, but tracing is enabled.

Change-Id: I64ca074942f6e89b4f5b5e3b6048b2b713c06df8
Reviewed-by: Tomi Korpipää <tomi.korpipaa@qt.io>
Reviewed-by: Janne Koskinen <janne.p.koskinen@qt.io>
(cherry picked from commit 257b3161c5c5e46cd040371da77cb6a06987cf50)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

src/tools/tracegen/ctf.cpp

@@ -15,6 +15,7 @@
 
 static void writePrologue(QTextStream &stream, const QString &fileName, const Provider &provider)
 {
+    writeCommonPrologue(stream);
     const QString guard = includeGuard(fileName);
 
     // include prefix text or qt headers only once

src/tools/tracegen/etw.cpp

@@ -104,6 +104,7 @@ static QString createGuid(const QUuid &uuid)
 
 static void writePrologue(QTextStream &stream, const QString &fileName, const Provider &provider)
 {
+    writeCommonPrologue(stream);
     QUuid uuid = QUuid::createUuidV5(QUuid(), provider.name.toLocal8Bit());
 
     const QString providerV = providerVar(provider.name);

src/tools/tracegen/helpers.cpp

@@ -6,6 +6,15 @@
 
 using namespace Qt::StringLiterals;
 
+void writeCommonPrologue(QTextStream &stream)
+{
+    stream << R"CPP(
+#ifndef Q_TRACEPOINT
+#error "Q_TRACEPOINT not set for the module, Q_TRACE not enabled."
+#endif
+)CPP";
+}
+
 QString typeToTypeName(const QString &name)
 {
     QString ret = name;

src/tools/tracegen/helpers.h

@@ -8,6 +8,7 @@
 
 #include <qlist.h>
 #include <qstring.h>
+#include <qtextstream.h>
 
 enum ParamType {
     LTTNG,
@@ -20,6 +21,8 @@ QString includeGuard(const QString &filename);
 QString formatFunctionSignature(const QList<Tracepoint::Argument> &args);
 QString formatParameterList(const Provider &provider, const QList<Tracepoint::Argument> &args, const QList<Tracepoint::Field> &fields, ParamType type);
 
+void writeCommonPrologue(QTextStream &stream);
+
 template <typename T>
 static QString aggregateListValues(int value, const QList<T> &list)
 {

src/tools/tracegen/lttng.cpp

@@ -101,6 +101,7 @@ static void writeCtfMacro(QTextStream &stream, const Provider &provider, const T
 
 static void writePrologue(QTextStream &stream, const QString &fileName, const Provider &provider)
 {
+    writeCommonPrologue(stream);
     const QString guard = includeGuard(fileName);
 
     stream << "#undef TRACEPOINT_PROVIDER\n";