From 9486a64b85cbf18c6b0cf84c7994add518c50124 Mon Sep 17 00:00:00 2001
From: Matti Kortelainen <matti.kortelainen@cern.ch>
Date: Wed, 10 Dec 2025 15:54:49 +0100
Subject: [PATCH 1/2] Fix LHEEventProduct auto_ptr<PdfInfo> read rule to cover
 all previous versions

---
 SimDataFormats/GeneratorProducts/src/classes_def.xml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/SimDataFormats/GeneratorProducts/src/classes_def.xml b/SimDataFormats/GeneratorProducts/src/classes_def.xml
index f2e9d93f012f6..77750c2578b82 100644
--- a/SimDataFormats/GeneratorProducts/src/classes_def.xml
+++ b/SimDataFormats/GeneratorProducts/src/classes_def.xml
@@ -241,7 +241,7 @@
   <version ClassVersion="14" checksum="905719452"/>
   <version ClassVersion="15" checksum="898288635"/>
  </class>
- <ioread sourceClass = "LHEEventProduct" version="[13]" targetClass="LHEEventProduct" source = "std::auto_ptr<gen::PdfInfo> pdf_;" target="pdf_">
+ <ioread sourceClass = "LHEEventProduct" version="[-13]" targetClass="LHEEventProduct" source = "std::auto_ptr<gen::PdfInfo> pdf_;" target="pdf_">
    <![CDATA[pdf_.reset(onfile.pdf_.get()); onfile.pdf_.release();]]>
  </ioread> 
  <ioread sourceClass = "LHEEventProduct" version="[-12]" targetClass="LHEEventProduct" source = "" target="npLO_">

From 54bdaa5b9dbbceaa3b815b2b86ca5b619dc593e8 Mon Sep 17 00:00:00 2001
From: Matti Kortelainen <matti.kortelainen@cern.ch>
Date: Wed, 10 Dec 2025 16:16:25 +0100
Subject: [PATCH 2/2] Evolve auto_ptr<PdfInfo>-to-unique_ptr read rules to
 avoid std::auto_ptr

std::auto_ptr was removed in C++17, and while kept in libstd++,
presently generates deprecation warnings in our builds. This pattern,
tested in IOPool/Input schema evoluytion tests allows the schema
evolution from auto_ptr in input file to unique_ptr in memory (and
output file) without using std::auto_ptr. The read rule depends on
ROOT 6.36.
---
 SimDataFormats/GeneratorProducts/src/classes.h   | 16 ++++++++++++++++
 .../GeneratorProducts/src/classes_def.xml        | 11 ++++++-----
 2 files changed, 22 insertions(+), 5 deletions(-)

diff --git a/SimDataFormats/GeneratorProducts/src/classes.h b/SimDataFormats/GeneratorProducts/src/classes.h
index 63a8fcc3b0af5..1d39debbf6ea8 100644
--- a/SimDataFormats/GeneratorProducts/src/classes.h
+++ b/SimDataFormats/GeneratorProducts/src/classes.h
@@ -39,3 +39,19 @@ namespace hepmc_rootio {
     }
   }
 }  // namespace hepmc_rootio
+
+// needed for backwards compatibility for auto_ptr<gen::PdfInfo>
+namespace pdfinfo_autoptr_rootio {
+  // Following the pattern in DataFormats/TestObjects/src/classes.h
+  template <typename T>
+  struct deprecated_auto_ptr {
+    // We use compat_auto_ptr only to assign the wrapped raw pointer
+    // to a unique pointer in an I/O customization rule.
+    // Therefore, we don't delete on destruction (because ownership
+    // gets transferred to the unique pointer).
+
+    // ~deprecated_auto_ptr() { delete _M_ptr; }
+
+    T* _M_ptr = nullptr;
+  };
+}  // namespace pdfinfo_autoptr_rootio
diff --git a/SimDataFormats/GeneratorProducts/src/classes_def.xml b/SimDataFormats/GeneratorProducts/src/classes_def.xml
index 77750c2578b82..80dce92c1be88 100644
--- a/SimDataFormats/GeneratorProducts/src/classes_def.xml
+++ b/SimDataFormats/GeneratorProducts/src/classes_def.xml
@@ -121,7 +121,8 @@
         <class name="gen::PdfInfo" ClassVersion="10">
   <version ClassVersion="10" checksum="876888052"/>
  </class>
-        <class name="std::auto_ptr&lt;gen::PdfInfo&gt;"/>
+        <class name="pdfinfo_autoptr_rootio::deprecated_auto_ptr<gen::PdfInfo>"/>
+        <ioread sourceClass="std::auto_ptr<gen::PdfInfo>" targetClass="pdfinfo_autoptr_rootio::deprecated_auto_ptr<gen::PdfInfo>"/>
 
 	<!-- GenRunInfoProduct -->
 
@@ -193,8 +194,8 @@
   <version ClassVersion="11" checksum="4154339631"/>
   <version ClassVersion="10" checksum="2479857328"/>
  </class>
- <ioread sourceClass = "GenEventInfoProduct" version="[-11]" targetClass="GenEventInfoProduct" source = "std::auto_ptr<gen::PdfInfo> pdf_;" target="pdf_">
-   <![CDATA[pdf_.reset(onfile.pdf_.get()); onfile.pdf_.release();]]>
+ <ioread sourceClass = "GenEventInfoProduct" version="[-11]" targetClass="GenEventInfoProduct" source = "pdfinfo_autoptr_rootio::deprecated_auto_ptr<gen::PdfInfo> pdf_;" target="pdf_">
+   <![CDATA[pdf_.reset(onfile.pdf_._M_ptr); onfile.pdf_._M_ptr = nullptr;]]>
  </ioread>
  <ioread sourceClass = "GenEventInfoProduct" version="[-10]" targetClass="GenEventInfoProduct" source = "" target="nMEPartons_">
     <![CDATA[nMEPartons_ = -1;]]>
@@ -241,8 +242,8 @@
   <version ClassVersion="14" checksum="905719452"/>
   <version ClassVersion="15" checksum="898288635"/>
  </class>
- <ioread sourceClass = "LHEEventProduct" version="[-13]" targetClass="LHEEventProduct" source = "std::auto_ptr<gen::PdfInfo> pdf_;" target="pdf_">
-   <![CDATA[pdf_.reset(onfile.pdf_.get()); onfile.pdf_.release();]]>
+ <ioread sourceClass = "LHEEventProduct" version="[-13]" targetClass="LHEEventProduct" source = "pdfinfo_autoptr_rootio::deprecated_auto_ptr<gen::PdfInfo> pdf_;" target="pdf_">
+   <![CDATA[pdf_.reset(onfile.pdf_._M_ptr); onfile.pdf_._M_ptr = nullptr;]]>
  </ioread> 
  <ioread sourceClass = "LHEEventProduct" version="[-12]" targetClass="LHEEventProduct" source = "" target="npLO_">
     <![CDATA[npLO_ = -99;]]>