[partition] Mark /boot or / as bootable

FIXES #1175

src/modules/partition/core/PartitionCoreModule.cpp

@@ -910,9 +910,23 @@ PartitionCoreModule::layoutApply( Device* dev,
     bool isEfi = PartUtils::isEfiSystem();
     QList< Partition* > partList = m_partLayout->execute( dev, firstSector, lastSector, luksPassphrase, parent, role );
 
-    foreach ( Partition* part, partList )
+    // Partition::mountPoint() tells us where it is mounted **now**, while
+    // PartitionInfo::mountPoint() says where it will be mounted in the target system.
+    // .. the latter is more interesting.
+    //
+    // If we have a separate /boot, mark that one as bootable, otherwise mark
+    // the root / as bootable.
+    //
+    // TODO: perhaps the partition that holds the bootloader?
+    const QString boot = QStringLiteral( "/boot" );
+    const QString root = QStringLiteral( "/" );
+    const auto is_boot = [&](Partition*p) -> bool {return PartitionInfo::mountPoint(p) == boot || p->mountPoint() == boot;};
+    const auto is_root = [&](Partition*p) -> bool {return PartitionInfo::mountPoint(p) == root || p->mountPoint() == root;};
+
+    const bool separate_boot_partition = std::find_if(partList.constBegin(), partList.constEnd(), is_boot) != partList.constEnd();
+    for( Partition* part : partList )
     {
-        if ( part->mountPoint() == "/" )
+        if (  ( separate_boot_partition && is_boot(part)) || (!separate_boot_partition && is_root(part)))
         {
             createPartition(
                 dev, part, part->activeFlags() | ( isEfi ? KPM_PARTITION_FLAG( None ) : KPM_PARTITION_FLAG( Boot ) ) );