2 files changed, 11 insertions, 7 deletions
diff --git a/src/plugins/cpptools/clangdiagnosticconfig.cpp b/src/plugins/cpptools/clangdiagnosticconfig.cpp
index 032d980316..51cf125366 100644
--- a/src/plugins/cpptools/clangdiagnosticconfig.cpp
+++ b/src/plugins/cpptools/clangdiagnosticconfig.cpp
@@ -190,10 +190,14 @@ ClangDiagnosticConfigs diagnosticConfigsFromSettings(QSettings *s)
         config.setId(Core::Id::fromSetting(s->value(diagnosticConfigIdKey)));
         config.setDisplayName(s->value(diagnosticConfigDisplayNameKey).toString());
         config.setClangOptions(s->value(diagnosticConfigWarningsKey).toStringList());
-        config.setClangTidyMode(static_cast<ClangDiagnosticConfig::TidyMode>(
-            s->value(diagnosticConfigsTidyModeKey).toInt()));
-        config.setClangTidyChecks(
-            s->value(diagnosticConfigsTidyChecksKey).toString());
+        const int tidyModeValue = s->value(diagnosticConfigsTidyModeKey).toInt();
+        if (tidyModeValue == 0) { // Convert from settings of <= Qt Creator 4.10
+            config.setClangTidyMode(ClangDiagnosticConfig::TidyMode::ChecksPrefixList);
+            config.setClangTidyChecks("-*");
+        } else {
+            config.setClangTidyMode(static_cast<ClangDiagnosticConfig::TidyMode>(tidyModeValue));
+            config.setClangTidyChecks(s->value(diagnosticConfigsTidyChecksKey).toString());
+        }
 
         config.setClazyMode(static_cast<ClangDiagnosticConfig::ClazyMode>(
             s->value(diagnosticConfigsClazyModeKey).toInt()));
diff --git a/src/plugins/cpptools/clangdiagnosticconfig.h b/src/plugins/cpptools/clangdiagnosticconfig.h
index ce7e25aa9e..da10a01c28 100644
--- a/src/plugins/cpptools/clangdiagnosticconfig.h
+++ b/src/plugins/cpptools/clangdiagnosticconfig.h
@@ -60,8 +60,8 @@ public:
     // Clang-Tidy
     enum class TidyMode
     {
-        Disabled,
-        ChecksPrefixList,
+        // Disabled, // Used by Qt Creator 4.10 and below.
+        ChecksPrefixList = 1,
         File,
         Default,
     };
@@ -90,7 +90,7 @@ private:
     Core::Id m_id;
     QString m_displayName;
     QStringList m_clangOptions;
-    TidyMode m_clangTidyMode = TidyMode::Disabled;
+    TidyMode m_clangTidyMode = TidyMode::Default;
     QString m_clangTidyChecks;
     QString m_clazyChecks;
     ClazyMode m_clazyMode = ClazyMode::Default;