[gparted] Use constant reference from btrfs::get_cache_entry() (!94)

[Curtis Gedak <gedakc src gnome org>]

commit 0a4761df46364e050d8d6426b2c067f800be535e
Author: Mike Fleetwood <mike fleetwood googlemail com>
Date:   Tue Nov 2 20:43:35 2021 +0000

    Use constant reference from btrfs::get_cache_entry() (!94)
    
    Method already returned a constant reference.  Change local variables to
    constant references to avoid copy constructing them.
    
    Closes !94 - Make more getter methods use return-by-constant-reference

 src/btrfs.cc | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)
---
diff --git a/src/btrfs.cc b/src/btrfs.cc
index 8d66fedf..b465908a 100644
--- a/src/btrfs.cc
+++ b/src/btrfs.cc
@@ -285,8 +285,8 @@ bool btrfs::resize( const Partition & partition_new, OperationDetail & operation
 {
        bool success = true ;
        const Glib::ustring& path = partition_new.get_path();
+       const BTRFS_Device& btrfs_dev = get_cache_entry(path);
 
-       BTRFS_Device btrfs_dev = get_cache_entry( path ) ;
        if ( btrfs_dev .devid == -1 )
        {
                operationdetail .add_child( OperationDetail(
@@ -400,7 +400,8 @@ void btrfs::clear_cache()
 //  Return empty string if not found (not mounted).
 Glib::ustring btrfs::get_mount_device( const Glib::ustring & path )
 {
-       BTRFS_Device btrfs_dev = get_cache_entry( path ) ;
+       const BTRFS_Device& btrfs_dev = get_cache_entry(path);
+
        if ( btrfs_dev .devid == -1 || btrfs_dev .members .empty() )
        {
                //WARNING:
@@ -421,7 +422,7 @@ Glib::ustring btrfs::get_mount_device( const Glib::ustring & path )
 
 std::vector<Glib::ustring> btrfs::get_members( const Glib::ustring & path )
 {
-       BTRFS_Device btrfs_dev = get_cache_entry( path ) ;
+       const BTRFS_Device& btrfs_dev = get_cache_entry(path);
        std::vector<Glib::ustring> membs;
        for ( unsigned int i = 0 ; i < btrfs_dev.members.size() ; i ++ )
                membs.push_back( btrfs_dev.members[i].m_name );