Moc: simplify showing a warning

Instead of changing the "index" member then restoring it, add a
symbolAt() method to get the Symbol in question, and pass it to
new warning() overload.

Change-Id: Ie84a6cf4d837f4ed694f617100e9556c2fc2eea3
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

src/tools/moc/moc.cpp

@@ -1931,13 +1931,10 @@ void Moc::checkProperties(ClassDef *cdef)
         }
 
         if (p.read.isEmpty() && p.member.isEmpty() && p.bind.isEmpty()) {
-            const qsizetype rewind = index;
-            if (p.location >= 0)
-                index = p.location;
             QByteArray msg = "Property declaration " + p.name + " has neither an associated QProperty<> member"
                              ", nor a READ accessor function nor an associated MEMBER variable. The property will be invalid.";
-            warning(msg.constData());
-            index = rewind;
+            const auto &sym = p.location >= 0 ? symbolAt(p.location) : Symbol();
+            warning(sym, msg.constData());
             if (p.write.isEmpty()) {
                 cdef->propertyList.removeAt(i);
                 --i;

src/tools/moc/parser.cpp

@@ -73,9 +73,14 @@ void Parser::error(const char *msg)
     exit(EXIT_FAILURE);
 }
 
+void Parser::warning(const Symbol &sym, QByteArrayView msg)
+{
+    if (displayWarnings)
+        printMsg("warning: %s\n", msg, sym);
+}
+
 void Parser::warning(const char *msg) {
-    if (displayWarnings && msg)
-        printMsg("warning: %s\n", msg, index > 0 ? symbol() : Symbol{});
+    warning(index > 0 ? symbol() : Symbol{}, msg);
 }
 
 void Parser::note(const char *msg) {

src/tools/moc/parser.h

@@ -44,10 +44,12 @@ public:
     inline QByteArray lexem() { return symbols.at(index-1).lexem();}
     inline QByteArray unquotedLexem() { return symbols.at(index-1).unquotedLexem();}
     inline const Symbol &symbol() { return symbols.at(index-1);}
+    inline const Symbol &symbolAt(qsizetype idx) { return symbols.at(idx); }
 
     Q_NORETURN void error(const Symbol &symbol);
     Q_NORETURN void error(const char *msg = nullptr);
     void warning(const char * = nullptr);
+    void warning(const Symbol &sym, QByteArrayView msg);
     void note(const char * = nullptr);
     void defaultErrorMsg(const Symbol &sym);
     void printMsg(QByteArrayView formatStringSuffix, QByteArrayView msg, const Symbol &sym);