BuildConfiguration: Add static helper to turn buildtype into a string

Use that helper in the projectexplorer instead of hardcoding a mapping
there.

Change-Id: I8720607a869c086569661fc9e9326ed6e0f85bb3
Reviewed-by: Ulf Hermann <ulf.hermann@theqtcompany.com>

src/plugins/projectexplorer/buildconfiguration.cpp

@@ -306,6 +306,21 @@ QString BuildConfiguration::disabledReason() const
     return QString();
 }
 
+QString BuildConfiguration::buildTypeName(BuildConfiguration::BuildType type)
+{
+    switch (type) {
+    case ProjectExplorer::BuildConfiguration::Debug:
+        return QLatin1String("debug");
+    case ProjectExplorer::BuildConfiguration::Profile:
+        return QLatin1String("profile");
+    case ProjectExplorer::BuildConfiguration::Release:
+        return QLatin1String("release");
+    case ProjectExplorer::BuildConfiguration::Unknown: // fallthrough
+    default:
+        return QLatin1String("unknown");
+    }
+}
+
 ///
 // IBuildConfigurationFactory
 ///

src/plugins/projectexplorer/buildconfiguration.h

@@ -91,6 +91,8 @@ public:
     };
     virtual BuildType buildType() const = 0;
 
+    static QString buildTypeName(BuildType type);
+
 signals:
     void environmentChanged();
     void buildDirectoryChanged();

src/plugins/projectexplorer/projectexplorer.cpp

@@ -1371,16 +1371,10 @@ bool ProjectExplorerPlugin::initialize(const QStringList &arguments, QString *er
     expander->registerVariable(Constants::VAR_CURRENTBUILD_TYPE,
         tr("The currently active build configuration's type."),
         [&]() -> QString {
-            if (BuildConfiguration *bc = activeBuildConfiguration()) {
+            BuildConfiguration *bc = activeBuildConfiguration();
-                BuildConfiguration::BuildType type = bc->buildType();
+            const BuildConfiguration::BuildType type
-                if (type == BuildConfiguration::Debug)
+                                   = bc ? bc->buildType() : BuildConfiguration::Unknown;
-                    return QLatin1String("debug");
+            return BuildConfiguration::buildTypeName(type);
-                if (type == BuildConfiguration::Release)
-                    return QLatin1String("release");
-                if (type == BuildConfiguration::Profile)
-                    return QLatin1String("profile");
-            }
-            return tr("unknown");
         });