From 99c76a3ff5b1a094593b52b0e9b22b300bde77b4 Mon Sep 17 00:00:00 2001
From: Christoph Oelckers <coelckers@users.noreply.github.com>
Date: Fri, 16 Jun 2023 21:53:42 +0200
Subject: [PATCH] - BCOMPATF_NOSECTIONMERGE is not safe for the self
 referencing sector hacks in the Final doom IWADs.

---
 src/maploader/compatibility.cpp  |  3 +--
 wadsrc_extra/static/iwadinfo.txt | 22 +++++++++++-----------
 2 files changed, 12 insertions(+), 13 deletions(-)

diff --git a/src/maploader/compatibility.cpp b/src/maploader/compatibility.cpp
index 2a0fa07491..1d135132dd 100644
--- a/src/maploader/compatibility.cpp
+++ b/src/maploader/compatibility.cpp
@@ -292,12 +292,11 @@ FName MapLoader::CheckCompatibility(MapData *map)
 	Level->ib_compatflags = 0;
 
 	// When playing Doom IWAD levels force BCOMPATF_NOSECTIONMERGE, COMPAT_SHORTTEX and COMPATF_LIGHT.
-	// I'm not sure if the IWAD maps actually need COMPATF_LIGHT but it certainly does not hurt. BCOMPATF_NOSECTIONMERGE is mainly for MAP18's sector 0
+	// I'm not sure if the IWAD maps actually need COMPATF_LIGHT but it certainly does not hurt.
 	// TNT's MAP31 also needs COMPATF_STAIRINDEX but that only gets activated for TNT.WAD.
 	if (fileSystem.GetFileContainer(map->lumpnum) == fileSystem.GetIwadNum() && (gameinfo.flags & GI_COMPATSHORTTEX) && Level->maptype == MAPTYPE_DOOM)
 	{
 		Level->ii_compatflags = COMPATF_SHORTTEX|COMPATF_LIGHT;
-		Level->ib_compatflags = BCOMPATF_NOSECTIONMERGE;
 		if (gameinfo.flags & GI_COMPATSTAIRS) Level->ii_compatflags |= COMPATF_STAIRINDEX;
 	}
 
diff --git a/wadsrc_extra/static/iwadinfo.txt b/wadsrc_extra/static/iwadinfo.txt
index a1c419d4e0..11387e29c1 100644
--- a/wadsrc_extra/static/iwadinfo.txt
+++ b/wadsrc_extra/static/iwadinfo.txt
@@ -326,7 +326,7 @@ IWad
 	Config = "Doom"
 	IWADName = "doom.wad", 2
 	Mapinfo = "mapinfo/ultdoom.txt"
-	Compatibility = "Shorttex"
+	Compatibility = "Shorttex", "nosectionmerge"
 	MustContain = "E1M1","E2M1","E2M2","E2M3","E2M4","E2M5","E2M6","E2M7","E2M8","E2M9",
 		          "E3M1","E3M2","E3M3","E3M4","E3M5","E3M6","E3M7","E3M8","E3M9",
 		          "DPHOOF","BFGGA0","HEADA1","CYBRA1","SPIDA1D1", "E4M2",
@@ -343,7 +343,7 @@ IWad
 	Config = "Doom"
 	IWADName = "doomunity.wad", 2
 	Mapinfo = "mapinfo/ultdoom.txt"
-	Compatibility = "Shorttex"
+	Compatibility = "Shorttex", "nosectionmerge"
 	MustContain = "E1M1","E2M1","E2M2","E2M3","E2M4","E2M5","E2M6","E2M7","E2M8","E2M9",
 		          "E3M1","E3M2","E3M3","E3M4","E3M5","E3M6","E3M7","E3M8","E3M9",
 		          "DPHOOF","BFGGA0","HEADA1","CYBRA1","SPIDA1D1", "E4M2",
@@ -375,7 +375,7 @@ IWad
 	Config = "Doom"
 	IWADName = "doom.wad"
 	Mapinfo = "mapinfo/doomxbox.txt"
-	Compatibility = "Shorttex"
+	Compatibility = "Shorttex", "nosectionmerge"
 	MustContain = "E1M1","E2M1","E2M2","E2M3","E2M4","E2M5","E2M6","E2M7","E2M8","E2M9",
 		          "E3M1","E3M2","E3M3","E3M4","E3M5","E3M6","E3M7","E3M8","E3M9",
 		          "DPHOOF","BFGGA0","HEADA1","CYBRA1","SPIDA1D1", "E4M2", "E1M10", "SEWERS"
@@ -391,7 +391,7 @@ IWad
 	Config = "Doom"
 	IWADName = "doom.wad"
 	Mapinfo = "mapinfo/ultdoom.txt"
-	Compatibility = "Shorttex"
+	Compatibility = "Shorttex", "nosectionmerge"
 	MustContain = "E1M1","E2M1","E2M2","E2M3","E2M4","E2M5","E2M6","E2M7","E2M8","E2M9",
 		          "E3M1","E3M2","E3M3","E3M4","E3M5","E3M6","E3M7","E3M8","E3M9",
 		          "DPHOOF","BFGGA0","HEADA1","CYBRA1","SPIDA1D1", "E4M2"
@@ -407,7 +407,7 @@ IWad
 	Config = "Doom"
 	IWADName = "doom.wad", 1
 	Mapinfo = "mapinfo/doom1.txt"
-	Compatibility = "Shorttex"
+	Compatibility = "Shorttex", "nosectionmerge"
 	MustContain = "E1M1","E2M1","E2M2","E2M3","E2M4","E2M5","E2M6","E2M7","E2M8","E2M9",
 		          "E3M1","E3M2","E3M3","E3M4","E3M5","E3M6","E3M7","E3M8","E3M9",
 		          "DPHOOF","BFGGA0","HEADA1","CYBRA1","SPIDA1D1"
@@ -422,7 +422,7 @@ IWad
 	Game = "Doom"
 	Config = "Doom"
 	Mapinfo = "mapinfo/doom1.txt"
-	Compatibility = "Shareware", "Shorttex"
+	Compatibility = "Shareware", "Shorttex", "nosectionmerge"
 	MustContain = "E1M1"
 	BannerColors = "54 54 54", "a8 a8 a8"
 	IgnoreTitlePatches = 1
@@ -492,7 +492,7 @@ IWad
 	Config = "Doom"
 	IWADName = "doom2.wad"
 	Mapinfo = "mapinfo/doom2bfg.txt"
-	Compatibility = "Shorttex"
+	Compatibility = "Shorttex", "nosectionmerge"
 	MustContain = "MAP01", "DMENUPIC", "M_ACPT", "M_CAN", "M_EXITO", "M_CHG"
 	BannerColors = "a8 00 00", "a8 a8 a8"
 	Load = "nerve.wad"
@@ -507,7 +507,7 @@ IWad
 	Config = "Doom"
 	IWADName = "doom2unity.wad"
 	Mapinfo = "mapinfo/doom2unity.txt"
-	Compatibility = "Shorttex"
+	Compatibility = "Shorttex", "nosectionmerge"
 	MustContain = "MAP01", "DMENUPIC"
 	BannerColors = "00 7c 00", "a8 a8 a8"
 	IgnoreTitlePatches = 1
@@ -522,7 +522,7 @@ IWad
 	Config = "Doom"
 	IWADName = "doom2.wad", 1
 	Mapinfo = "mapinfo/doom2xbox.txt"
-	Compatibility = "Shorttex"
+	Compatibility = "Shorttex", "nosectionmerge"
 	MustContain = "MAP01", "MAP33", "CWILV32"
 	BannerColors = "18 18 18", "a8 a8 a8"
 	IgnoreTitlePatches = 1
@@ -538,7 +538,7 @@ IWad
 	Config = "Doom"
 	IWADName = "doom2f.wad", 1
 	Mapinfo = "mapinfo/doom2.txt"
-	Compatibility = "Shorttex"
+	Compatibility = "Shorttex", "nosectionmerge"
 	MustContain = "MAP01", "WIOBJ"
 	BannerColors = "ff ff ff", "a8 00 00"
 }
@@ -552,7 +552,7 @@ IWad
 	Config = "Doom"
 	IWADName = "doom2.wad", 1
 	Mapinfo = "mapinfo/doom2.txt"
-	Compatibility = "Shorttex"
+	Compatibility = "Shorttex", "nosectionmerge"
 	MustContain = "MAP01"
 	BannerColors = "a8 00 00", "a8 a8 a8"
 	IgnoreTitlePatches = 1