1 files changed, 21 insertions, 9 deletions
diff --git a/src/tools/moc/main.cpp b/src/tools/moc/main.cpp
index 71b9757ebc..bb51352519 100644
--- a/src/tools/moc/main.cpp
+++ b/src/tools/moc/main.cpp
@@ -330,7 +330,7 @@ int runMoc(int argc, char **argv)
     if (parser.isSet(collectOption))
         return collectJson(files, output, hasOptionFiles);
 
-    if (files.count() > 1) {
+    if (files.size() > 1) {
         error(qPrintable("Too many input files specified: '"_L1 + files.join("' '"_L1) + u'\''));
         parser.showHelp(1);
     } else if (!files.isEmpty()) {
@@ -399,7 +399,7 @@ int runMoc(int argc, char **argv)
     for (const QString &arg : defines) {
         QByteArray name = arg.toLocal8Bit();
         QByteArray value("1");
-        int eq = name.indexOf('=');
+        const qsizetype eq = name.indexOf('=');
         if (eq >= 0) {
             value = name.mid(eq + 1);
             name = name.left(eq);
@@ -449,11 +449,14 @@ int runMoc(int argc, char **argv)
 
     if (filename.isEmpty()) {
         filename = QStringLiteral("standard input");
-        in.open(stdin, QIODevice::ReadOnly);
+        if (!in.open(stdin, QIODevice::ReadOnly)) {
+            fprintf(stderr, "moc: cannot open standard input: %s\n", qPrintable(in.errorString()));
+            return 1;
+        }
     } else {
         in.setFileName(filename);
         if (!in.open(QIODevice::ReadOnly)) {
-            fprintf(stderr, "moc: %s: No such file\n", qPrintable(filename));
+            fprintf(stderr, "moc: cannot open %s: %s\n", qPrintable(filename), qPrintable(in.errorString()));
             return 1;
         }
         moc.filename = filename.toLocal8Bit();
@@ -536,7 +539,10 @@ int runMoc(int argc, char **argv)
         if (!out)
 #endif
         {
-            fprintf(stderr, "moc: Cannot create %s\n", QFile::encodeName(output).constData());
+            const auto fopen_errno = errno;
+            fprintf(stderr, "moc: Cannot create %s. Error: %s\n",
+                    QFile::encodeName(output).constData(),
+                    strerror(fopen_errno));
             return 1;
         }
 
@@ -549,9 +555,12 @@ int runMoc(int argc, char **argv)
             f = fopen(QFile::encodeName(jsonOutputFileName).constData(), "w");
             if (!f)
 #endif
-                fprintf(stderr, "moc: Cannot create JSON output file %s. %s\n",
+            {
+                const auto fopen_errno = errno;
+                fprintf(stderr, "moc: Cannot create JSON output file %s. Error: %s\n",
                         QFile::encodeName(jsonOutputFileName).constData(),
-                        strerror(errno));
+                        strerror(fopen_errno));
+            }
             jsonOutput.reset(f);
         }
     } else { // use stdout
@@ -596,9 +605,12 @@ int runMoc(int argc, char **argv)
         depFileHandleRaw = fopen(QFile::encodeName(depOutputFileName).constData(), "w");
         if (!depFileHandleRaw)
 #endif
-            fprintf(stderr, "moc: Cannot create dep output file '%s'. %s\n",
+        {
+            const auto fopen_errno = errno;
+            fprintf(stderr, "moc: Cannot create dep output file '%s'. Error: %s\n",
                     QFile::encodeName(depOutputFileName).constData(),
-                    strerror(errno));
+                    strerror(fopen_errno));
+        }
         depFileHandle.reset(depFileHandleRaw);
 
         if (!depFileHandle.isNull()) {