From 2977d737de15239fa4ec08eb3176e8af46fc6609 Mon Sep 17 00:00:00 2001
From: Sam Estep <sam@samestep.com>
Date: Fri, 22 May 2026 23:54:37 -0400
Subject: [PATCH] applgrid: fix build after root update

Assisted-by: Claude:opus-4.7
---
 pkgs/by-name/ap/applgrid/TFileStringLinkDef.h    |  6 ++++++
 pkgs/by-name/ap/applgrid/TFileVectorLinkDef.h    |  6 ++++++
 pkgs/by-name/ap/applgrid/package.nix             | 11 +++++++++++
 pkgs/by-name/ap/applgrid/rootcling-linkdef.patch | 11 +++++++++++
 4 files changed, 34 insertions(+)
 create mode 100644 pkgs/by-name/ap/applgrid/TFileStringLinkDef.h
 create mode 100644 pkgs/by-name/ap/applgrid/TFileVectorLinkDef.h
 create mode 100644 pkgs/by-name/ap/applgrid/rootcling-linkdef.patch

diff --git a/pkgs/by-name/ap/applgrid/TFileStringLinkDef.h b/pkgs/by-name/ap/applgrid/TFileStringLinkDef.h
new file mode 100644
index 000000000000..ce59a4a65321
--- /dev/null
+++ b/pkgs/by-name/ap/applgrid/TFileStringLinkDef.h
@@ -0,0 +1,6 @@
+#ifdef __CLING__
+#pragma link off all globals;
+#pragma link off all classes;
+#pragma link off all functions;
+#pragma link C++ class TFileString+;
+#endif
diff --git a/pkgs/by-name/ap/applgrid/TFileVectorLinkDef.h b/pkgs/by-name/ap/applgrid/TFileVectorLinkDef.h
new file mode 100644
index 000000000000..07ba83655d5e
--- /dev/null
+++ b/pkgs/by-name/ap/applgrid/TFileVectorLinkDef.h
@@ -0,0 +1,6 @@
+#ifdef __CLING__
+#pragma link off all globals;
+#pragma link off all classes;
+#pragma link off all functions;
+#pragma link C++ class TFileVector+;
+#endif
diff --git a/pkgs/by-name/ap/applgrid/package.nix b/pkgs/by-name/ap/applgrid/package.nix
index c578ade96705..136ab20b5656 100644
--- a/pkgs/by-name/ap/applgrid/package.nix
+++ b/pkgs/by-name/ap/applgrid/package.nix
@@ -18,7 +18,18 @@ stdenv.mkDerivation (finalAttrs: {
     hash = "sha256-h+ZNGj33FIwg4fOCyfGJrUKM2vDDQl76JcLhtboAOtc=";
   };
 
+  patches = [
+    # ROOT 6.40 made rootcling fail when no selection rules are provided
+    # (https://root.cern/doc/v640/release-notes.html#core-libraries). The patch
+    # appends $*LinkDef.h to the dictionary pattern rule so rootcint picks up
+    # the LinkDef.h files we drop into src/ in postPatch.
+    ./rootcling-linkdef.patch
+  ];
+
   postPatch = ''
+    cp ${./TFileStringLinkDef.h} src/TFileStringLinkDef.h
+    cp ${./TFileVectorLinkDef.h} src/TFileVectorLinkDef.h
+
     sed -i appl_grid/serialise_base.h -e '1i#include <cstdint>'
   '';
 
diff --git a/pkgs/by-name/ap/applgrid/rootcling-linkdef.patch b/pkgs/by-name/ap/applgrid/rootcling-linkdef.patch
new file mode 100644
index 000000000000..e969dc7f25c7
--- /dev/null
+++ b/pkgs/by-name/ap/applgrid/rootcling-linkdef.patch
@@ -0,0 +1,11 @@
+--- a/src/Makefile.in
++++ b/src/Makefile.in
+@@ -1027,7 +1027,7 @@
+ 	$(CC) $(AM_CFLAGS) -c $<
+ 
+ @USE_ROOT_TRUE@%Dict.cxx : %.h %.cxx
+-@USE_ROOT_TRUE@	$(CINT) -f $@ -c $< -I.. 
++@USE_ROOT_TRUE@	$(CINT) -f $@ -c $< -I.. $*LinkDef.h
+ 
+ #../appl_grid/$*LinkDef.h
+