From 9d1031771e4a30548d89efa49580e3d8b6dae119 Mon Sep 17 00:00:00 2001
From: Pavel Sanda <sanda@lyx.org>
Date: Sat, 3 Apr 2021 13:19:53 +0200
Subject: [PATCH] Fix #4658: showing diff between original and emergency files.

https://www.mail-archive.com/lyx-devel@lists.lyx.org/msg215796.html
---
 src/Buffer.cpp                  | 17 ++++++++++++++++-
 src/frontends/qt/GuiCompare.cpp | 16 +++++++++++++---
 2 files changed, 29 insertions(+), 4 deletions(-)

diff --git a/src/Buffer.cpp b/src/Buffer.cpp
index fdce444aef..e848b0f69b 100644
--- a/src/Buffer.cpp
+++ b/src/Buffer.cpp
@@ -4694,7 +4694,7 @@ Buffer::ReadStatus Buffer::loadEmergency()
 		"%1$s exists.\n\nRecover emergency save?"), file);
 
 	int const load_emerg = Alert::prompt(_("Load emergency save?"), text,
-		0, 2, _("&Recover"), _("&Load Original"), _("&Cancel"));
+		0, 3, _("&Recover"), _("&Load Original"), _("&Only show difference"), _("&Cancel"));
 
 	switch (load_emerg)
 	{
@@ -4769,6 +4769,21 @@ Buffer::ReadStatus Buffer::loadEmergency()
 		return ReadOriginal;
 	}
 
+	case 2: {
+		string f1 = d->filename.absFileName();
+		string f2 = emergencyFile.absFileName();
+		if (loadThisLyXFile(d->filename) != ReadSuccess)
+			return ReadCancel;
+		string par = "compare run-blocking " + quoteName(f1) + " " + quoteName(f2);
+		LYXERR(Debug::FILES, par << "\n");
+		lyx::dispatch(FuncRequest(LFUN_DIALOG_SHOW, par));
+
+		//release the emergency buffer loaded by compare
+		Buffer * emerBuffer = theBufferList().getBuffer(emergencyFile);
+		if (emerBuffer) theBufferList().release(emerBuffer);
+
+		return ReadCancel; //Release the buffer of Original immediatelly
+	}
 	default:
 		break;
 	}
diff --git a/src/frontends/qt/GuiCompare.cpp b/src/frontends/qt/GuiCompare.cpp
index e48be86f22..7f6b00f44a 100644
--- a/src/frontends/qt/GuiCompare.cpp
+++ b/src/frontends/qt/GuiCompare.cpp
@@ -318,7 +318,13 @@ int GuiCompare::run(bool blocking_mode)
 		return 0;
 
 	dest_buffer_->changed(true);
-	dest_buffer_->markDirty();
+	if (blocking_mode)
+		//blocking mode is infinitive and we don't want diff autosave
+		//if user decides to kill ther running lyx instance
+		dest_buffer_->markClean();
+	else
+		dest_buffer_->markDirty();
+
 
 	// get the options from the dialog
 	CompareOptions options;
@@ -364,10 +370,14 @@ bool GuiCompare::initialiseParams(std::string const &par)
 				return false;
 			}
 
-			// Wait for the Compare function to process in a thread (2 minute timeout)
-			compare_->wait(120000);
+			// Wait for the Compare function to process in a thread
+			compare_->wait();
 
 			finished(false);
+			//Hiding dialog does not work as intended through finished routine, because showView
+			//is triggered after initialiseParams returns true. So we return false, warning will
+			//show on the terminal though.
+			return false;
 		}
 	}
 
-- 
2.39.5