Avoid blocking read from stdin when collecting json files

Change the behavior of moc when collecting json files. If argument files
are specified, suppose moc received empty input and skip input from
standard input.

Pick-to: 6.1
Fixes: QTBUG-93504
Change-Id: I45ec790ed458f1fae543d069555bc8abc6560816
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>

3 files changed, 9 insertions, 6 deletions

diff --git a/src/tools/moc/collectjson.cpp b/src/tools/moc/collectjson.cpp
index ed65a9ed08..6577a3216b 100644
--- a/src/tools/moc/collectjson.cpp
+++ b/src/tools/moc/collectjson.cpp
@@ -51,7 +51,7 @@ static bool readFromDevice(QIODevice *device, QJsonArray *allMetaObjects)
     return true;
 }
 
-int collectJson(const QStringList &jsonFiles, const QString &outputFile)
+int collectJson(const QStringList &jsonFiles, const QString &outputFile, bool skipStdIn)
 {
     QHashSeed::setDeterministicGlobalSeed();
 
@@ -70,7 +70,7 @@ int collectJson(const QStringList &jsonFiles, const QString &outputFile)
     }
 
     QJsonArray allMetaObjects;
-    if (jsonFiles.isEmpty()) {
+    if (jsonFiles.isEmpty() && !skipStdIn) {
         QFile f;
         if (!f.open(stdin, QIODevice::ReadOnly)) {
             fprintf(stderr, "Error opening stdin for reading\n");
diff --git a/src/tools/moc/collectjson.h b/src/tools/moc/collectjson.h
index 9d329c96ca..3a33952a54 100644
--- a/src/tools/moc/collectjson.h
+++ b/src/tools/moc/collectjson.h
@@ -35,7 +35,7 @@
 
 QT_BEGIN_NAMESPACE
 
-int collectJson(const QStringList &jsonFiles, const QString &outputFile);
+int collectJson(const QStringList &jsonFiles, const QString &outputFile, bool skipStdIn);
 
 QT_END_NAMESPACE
 
diff --git a/src/tools/moc/main.cpp b/src/tools/moc/main.cpp
index 1cb383c92f..a2790fa1f7 100644
--- a/src/tools/moc/main.cpp
+++ b/src/tools/moc/main.cpp
@@ -145,9 +145,10 @@ QByteArray composePreprocessorOutput(const Symbols &symbols) {
     return output;
 }
 
-static QStringList argumentsFromCommandLineAndFile(const QStringList &arguments)
+static QStringList argumentsFromCommandLineAndFile(const QStringList &arguments, bool &hasOptionFiles)
 {
     QStringList allArguments;
+    hasOptionFiles = false;
     allArguments.reserve(arguments.size());
     for (const QString &argument : arguments) {
         // "@file" doesn't start with a '-' so we can't use QCommandLineParser for it
@@ -163,6 +164,7 @@ static QStringList argumentsFromCommandLineAndFile(const QStringList &arguments)
                 error("Cannot open options file specified with @");
                 return QStringList();
             }
+            hasOptionFiles = true;
             while (!f.atEnd()) {
                 QString line = QString::fromLocal8Bit(f.readLine().trimmed());
                 if (!line.isEmpty())
@@ -378,7 +380,8 @@ int runMoc(int argc, char **argv)
     parser.addPositionalArgument(QStringLiteral("[MOC generated json file]"),
                                  QStringLiteral("MOC generated json output"));
 
-    const QStringList arguments = argumentsFromCommandLineAndFile(app.arguments());
+    bool hasOptionFiles = false;
+    const QStringList arguments = argumentsFromCommandLineAndFile(app.arguments(), hasOptionFiles);
     if (arguments.isEmpty())
         return 1;
 
@@ -387,7 +390,7 @@ int runMoc(int argc, char **argv)
     const QStringList files = parser.positionalArguments();
     output = parser.value(outputOption);
     if (parser.isSet(collectOption))
-        return collectJson(files, output);
+        return collectJson(files, output, hasOptionFiles);
 
     if (files.count() > 1) {
         error(qPrintable(QLatin1String("Too many input files specified: '") + files.join(QLatin1String("' '")) + QLatin1Char('\'')));