Git: Show error when pull fails due to unstaged changes

When git pull fails due to unstaged changes in the working directory,
show an informative error message instead of silently failing.

Fixes https://gitlab.com/kicad/code/kicad/-/issues/20363

common/git/libgit_backend.cpp

@@ -1018,13 +1018,61 @@ PullResult LIBGIT_BACKEND::handleFastForward( GIT_PULL_HANDLER* aHandler )
     return PullResult::FastForward;
 }
 
+bool LIBGIT_BACKEND::hasUnstagedChanges( git_repository* aRepo )
+{
+    if( !aRepo )
+        return false;
+
+    git_status_options opts;
+    git_status_init_options( &opts, GIT_STATUS_OPTIONS_VERSION );
+
+    // Only check workdir changes (unstaged), not index changes (staged)
+    opts.show = GIT_STATUS_SHOW_WORKDIR_ONLY;
+    opts.flags = GIT_STATUS_OPT_INCLUDE_UNTRACKED;
+
+    git_status_list* status_list = nullptr;
+
+    if( git_status_list_new( &status_list, aRepo, &opts ) != GIT_OK )
+    {
+        wxLogTrace( traceGit, "Failed to get status list: %s", KIGIT_COMMON::GetLastGitError() );
+        return false;
+    }
+
+    KIGIT::GitStatusListPtr status_list_ptr( status_list );
+    size_t count = git_status_list_entrycount( status_list );
+
+    // Check if any of the entries are actual modifications (not just untracked files)
+    for( size_t ii = 0; ii < count; ++ii )
+    {
+        const git_status_entry* entry = git_status_byindex( status_list, ii );
+
+        // Check for actual workdir modifications, not just untracked files
+        if( entry->status & ( GIT_STATUS_WT_MODIFIED | GIT_STATUS_WT_DELETED | GIT_STATUS_WT_TYPECHANGE ) )
+        {
+            return true;
+        }
+    }
+
+    return false;
+}
+
 PullResult LIBGIT_BACKEND::handleMerge( GIT_PULL_HANDLER* aHandler,
                                         const git_annotated_commit** aMergeHeads,
                                         size_t aMergeHeadsCount )
 {
+    // Check for unstaged changes before attempting merge
+    if( hasUnstagedChanges( aHandler->GetRepo() ) )
+    {
+        aHandler->AddErrorString(
+                _( "Cannot merge: you have unstaged changes. "
+                   "Please commit or stash them before pulling." ) );
+        return PullResult::DirtyWorkdir;
+    }
+
     if( git_merge( aHandler->GetRepo(), aMergeHeads, aMergeHeadsCount, nullptr, nullptr ) )
     {
-        aHandler->AddErrorString( _( "Merge failed" ) );
+        wxString errorMsg = KIGIT_COMMON::GetLastGitError();
+        aHandler->AddErrorString( wxString::Format( _( "Merge failed: %s" ), errorMsg ) );
         return PullResult::MergeFailed;
     }
 
@@ -1035,6 +1083,15 @@ PullResult LIBGIT_BACKEND::handleRebase( GIT_PULL_HANDLER* aHandler,
                                          const git_annotated_commit** aMergeHeads,
                                          size_t aMergeHeadsCount )
 {
+    // Check for unstaged changes before attempting rebase
+    if( hasUnstagedChanges( aHandler->GetRepo() ) )
+    {
+        aHandler->AddErrorString(
+                _( "Cannot pull with rebase: you have unstaged changes. "
+                   "Please commit or stash them before pulling." ) );
+        return PullResult::DirtyWorkdir;
+    }
+
     git_rebase_options rebase_opts;
     git_rebase_init_options( &rebase_opts, GIT_REBASE_OPTIONS_VERSION );
 
@@ -1042,7 +1099,8 @@ PullResult LIBGIT_BACKEND::handleRebase( GIT_PULL_HANDLER* aHandler,
 
     if( git_rebase_init( &rebase, aHandler->GetRepo(), nullptr, aMergeHeads[0], nullptr, &rebase_opts ) )
     {
-        aHandler->AddErrorString( _( "Rebase failed to start" ) );
+        wxString errorMsg = KIGIT_COMMON::GetLastGitError();
+        aHandler->AddErrorString( wxString::Format( _( "Rebase failed to start: %s" ), errorMsg ) );
         return PullResult::MergeFailed;
     }
 
@@ -1051,19 +1109,22 @@ PullResult LIBGIT_BACKEND::handleRebase( GIT_PULL_HANDLER* aHandler,
     while( true )
     {
         git_rebase_operation* op = nullptr;
+
         if( git_rebase_next( &op, rebase ) != 0 )
             break;
 
         if( git_rebase_commit( nullptr, rebase, nullptr, nullptr, nullptr, nullptr ) )
         {
-            aHandler->AddErrorString( _( "Rebase commit failed" ) );
+            wxString errorMsg = KIGIT_COMMON::GetLastGitError();
+            aHandler->AddErrorString( wxString::Format( _( "Rebase commit failed: %s" ), errorMsg ) );
             return PullResult::MergeFailed;
         }
     }
 
     if( git_rebase_finish( rebase, nullptr ) )
     {
-        aHandler->AddErrorString( _( "Rebase finish failed" ) );
+        wxString errorMsg = KIGIT_COMMON::GetLastGitError();
+        aHandler->AddErrorString( wxString::Format( _( "Rebase finish failed: %s" ), errorMsg ) );
         return PullResult::MergeFailed;
     }