[libcalamaresui] Fix up module dependency checking

- If a module exists, and has unmet dependencies, then
   that is only a problem if the module itself is *used*.
   Merely existing is ok.

This triggers on FreeBSD, where partition isn't built, but
bootloader depends on partition -- so you can never start
Calamares on FreeBSD, because bootloader depends on something
non-existent.

Relax the check: just warn, and only fail if a non-existent
module is used (all those with unmet dependencies are considered
non-existent).

src/libcalamaresui/modulesystem/ModuleManager.cpp

@@ -188,11 +188,15 @@ findCustomInstance( const Settings::InstanceDescriptionList& customInstances, co
 void
 ModuleManager::loadModules()
 {
-    QStringList failedModules = checkDependencies();
+    if (checkDependencies())
+    {
+        cWarning() << "Some installed modules have unmet dependencies.";
+    }
     Settings::InstanceDescriptionList customInstances = Settings::instance()->customModuleInstances();
 
+    QStringList failedModules;
     const auto modulesSequence
-        = failedModules.isEmpty() ? Settings::instance()->modulesSequence() : Settings::ModuleSequence();
+        = Settings::instance()->modulesSequence() ;
     for ( const auto& modulePhase : modulesSequence )
     {
         ModuleSystem::Action currentAction = modulePhase.first;
@@ -270,7 +274,7 @@ ModuleManager::loadModules()
                     continue;
                 }
 
-                if ( !checkDependencies( *thisModule ) )
+                if ( !checkModuleDependencies( *thisModule ) )
                 {
                     // Error message is already printed
                     failedModules.append( instanceKey.toString() );
@@ -351,10 +355,10 @@ missingRequiredModules( const QStringList& required, const QMap< QString, QVaria
     return l;
 }
 
-QStringList
+size_t
 ModuleManager::checkDependencies()
 {
-    QStringList failed;
+    size_t numberRemoved = 0;
     bool somethingWasRemovedBecauseOfUnmetDependencies = false;
 
     // This goes through the map of available modules, and deletes those whose
@@ -373,19 +377,18 @@ ModuleManager::checkDependencies()
                 QString moduleName = it->value( "name" ).toString();
                 somethingWasRemovedBecauseOfUnmetDependencies = true;
                 m_availableDescriptorsByModuleName.erase( it );
-                failed << moduleName;
-                cWarning() << "Module" << moduleName << "requires modules" << Logger::DebugList( unmet );
-                cWarning() << Logger::SubEntry << "but these are not available (listed in settings, or installed).";
+                numberRemoved++;
+                cWarning() << "Module" << moduleName << "requires missing modules" << Logger::DebugList( unmet );
                 break;
             }
         }
     } while ( somethingWasRemovedBecauseOfUnmetDependencies );
 
-    return failed;
+    return numberRemoved;
 }
 
 bool
-ModuleManager::checkDependencies( const Module& m )
+ModuleManager::checkModuleDependencies( const Module& m )
 {
     bool allRequirementsFound = true;
     QStringList requiredModules

src/libcalamaresui/modulesystem/ModuleManager.h

@@ -106,15 +106,17 @@ private slots:
 private:
     /**
      * Check in a general sense whether the dependencies between
-     * modules are valid. Returns a list of module names that
-     * do **not** have their requirements met.
+     * modules are valid. Returns the number of modules that
+     * have missing dependencies -- this is **not** a problem
+     * unless any of those modules are actually used.
      *
-     * Returns an empty list on success.
+     * Returns 0 on success.
      *
      * Also modifies m_availableDescriptorsByModuleName to remove
-     * all the entries that fail.
+     * all the entries that (so that later, when we try to look
+     * them up, they are not found).
      */
-    QStringList checkDependencies();
+    size_t checkDependencies();
 
     /**
      * Check for this specific module if its required modules have
@@ -122,7 +124,7 @@ private:
      *
      * Returns true if the requirements are met.
      */
-    bool checkDependencies( const Module& );
+    bool checkModuleDependencies( const Module& );
 
     QMap< QString, QVariantMap > m_availableDescriptorsByModuleName;
     QMap< QString, QString > m_moduleDirectoriesByModuleName;