Add DisabledReason for discarding from a multiselection of commits

pkg/gui/controllers/commits_files_controller.go

@@ -351,6 +351,13 @@ func (self *CommitFilesController) canDiscardFileChanges(nodes []*filetree.Commi
 		}
 	}
 
+	if self.c.Contexts().LocalCommits.AreMultipleItemsSelected() {
+		return &types.DisabledReason{
+			Text:             self.c.Tr.CannotDiscardFromMultipleCommits,
+			ShowErrorInPanel: true,
+		}
+	}
+
 	if self.c.Git().Status.WorkingTreeState().Any() {
 		return &types.DisabledReason{
 			Text:             self.c.Tr.CantPatchWhileRebasingError,

pkg/i18n/english.go

@@ -434,6 +434,7 @@ type TranslationSet struct {
 	CheckoutCommitFileTooltip             string
 	CannotCheckoutWithModifiedFilesErr    string
 	CanOnlyDiscardFromLocalCommits        string
+	CannotDiscardFromMultipleCommits      string
 	Remove                                string
 	DiscardOldFileChangeTooltip           string
 	DiscardFileChangesTitle               string
@@ -1543,6 +1544,7 @@ func EnglishTranslationSet() *TranslationSet {
 		CheckoutCommitFileTooltip:            "Checkout file. This replaces the file in your working tree with the version from the selected commit.",
 		CannotCheckoutWithModifiedFilesErr:   "You have local modifications for the file(s) you are trying to check out. You need to stash or discard these first.",
 		CanOnlyDiscardFromLocalCommits:       "Changes can only be discarded from local commits",
+		CannotDiscardFromMultipleCommits:     "Changes cannot be discarded from a multiselection of commits",
 		Remove:                               "Remove",
 		DiscardOldFileChangeTooltip:          "Discard this commit's changes to this file. This runs an interactive rebase in the background, so you may get a merge conflict if a later commit also changes this file.",
 		DiscardFileChangesTitle:              "Discard file changes",