From 19e38fbae692cecfee661969b4d9f4aa38260f46 Mon Sep 17 00:00:00 2001
From: Jonas Hahnfeld <jonas.hahnfeld@cern.ch>
Date: Mon, 12 Jan 2026 15:11:05 +0100
Subject: [PATCH 1/2] [hist] Add RBinIndex conversion overloads

This avoids sign conversion warnings for signed integers, for example
from literals. We then need all overloads to guarantee one unambiguous
constructor candidate following integer promotion.
---
 hist/histv7/inc/ROOT/RBinIndex.hxx | 31 +++++++++++++++++++++++++++++-
 hist/histv7/test/hist_index.cxx    | 18 +++++++++++++++++
 2 files changed, 48 insertions(+), 1 deletion(-)

diff --git a/hist/histv7/inc/ROOT/RBinIndex.hxx b/hist/histv7/inc/ROOT/RBinIndex.hxx
index d7954f56a7f34..475cc4d62263f 100644
--- a/hist/histv7/inc/ROOT/RBinIndex.hxx
+++ b/hist/histv7/inc/ROOT/RBinIndex.hxx
@@ -28,6 +28,9 @@ class RBinIndex final {
    // We use std::uint64_t instead of std::size_t for the index because for sparse histograms, not all bins have to be
    // allocated in memory. However, we require that the index has at least that size.
    static_assert(sizeof(std::uint64_t) >= sizeof(std::size_t), "index type not large enough to address all bins");
+   // During construction, we expect that any standard integer fits in std::uint64_t.
+   static_assert(sizeof(std::uint64_t) >= sizeof(unsigned long long),
+                 "index type not large enough to store any standard integer");
 
    std::uint64_t fIndex = kInvalidIndex;
 
@@ -36,7 +39,33 @@ public:
    RBinIndex() = default;
 
    /// Construct a bin index for a normal bin.
-   RBinIndex(std::uint64_t index) : fIndex(index) { assert(IsNormal()); }
+   RBinIndex(unsigned int index) : RBinIndex(static_cast<unsigned long long>(index)) {}
+
+   /// Construct a bin index for a normal bin.
+   RBinIndex(unsigned long index) : RBinIndex(static_cast<unsigned long long>(index)) {}
+
+   /// Construct a bin index for a normal bin.
+   RBinIndex(unsigned long long index) : fIndex(index) { assert(IsNormal()); }
+
+   /// Construct a bin index for a normal bin.
+   ///
+   /// \param[in] index signed integer that must not be negative
+   RBinIndex(int index) : RBinIndex(static_cast<long long>(index)) {}
+
+   /// Construct a bin index for a normal bin.
+   ///
+   /// \param[in] index signed integer that must not be negative
+   RBinIndex(long index) : RBinIndex(static_cast<long long>(index)) {}
+
+   /// Construct a bin index for a normal bin.
+   ///
+   /// \param[in] index signed integer that must not be negative
+   RBinIndex(long long index)
+   {
+      assert(index >= 0);
+      fIndex = static_cast<std::uint64_t>(index);
+      assert(IsNormal());
+   }
 
    /// Return the index for a normal bin.
    std::uint64_t GetIndex() const
diff --git a/hist/histv7/test/hist_index.cxx b/hist/histv7/test/hist_index.cxx
index 93976a2532a3a..19591b7896350 100644
--- a/hist/histv7/test/hist_index.cxx
+++ b/hist/histv7/test/hist_index.cxx
@@ -4,6 +4,10 @@
 #include <iterator>
 #include <vector>
 
+#ifndef TYPED_TEST_SUITE
+#define TYPED_TEST_SUITE TYPED_TEST_CASE
+#endif
+
 TEST(RBinIndex, Constructor)
 {
    const RBinIndex invalid;
@@ -152,6 +156,20 @@ TEST(RBinIndex, Relation)
    EXPECT_FALSE(underflow >= overflow);
 }
 
+template <typename T>
+class RBinIndexConversion : public testing::Test {};
+
+using IntegerTypes = testing::Types<signed char, unsigned char, short, unsigned short, int, unsigned int, long,
+                                    unsigned long, long long, unsigned long long>;
+TYPED_TEST_SUITE(RBinIndexConversion, IntegerTypes);
+
+TYPED_TEST(RBinIndexConversion, Constructor)
+{
+   const TypeParam input = 1;
+   const RBinIndex index(input);
+   EXPECT_EQ(index.GetIndex(), 1);
+}
+
 using ROOT::Experimental::Internal::CreateBinIndexRange;
 
 TEST(RBinIndexRange, ConstructorCreate)

From 1f3840eaebafa17cd8f017f9ee6556d463947173 Mon Sep 17 00:00:00 2001
From: Jonas Hahnfeld <jonas.hahnfeld@cern.ch>
Date: Wed, 14 Jan 2026 09:14:03 +0100
Subject: [PATCH 2/2] [ci] Enable compiler warnings in standalone histv7

---
 .github/workflows/histv7.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/histv7.yml b/.github/workflows/histv7.yml
index a3b152dbed370..365889d679e4a 100644
--- a/.github/workflows/histv7.yml
+++ b/.github/workflows/histv7.yml
@@ -16,7 +16,7 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v4
       - name: Configure
-        run: cmake -B build -DCMAKE_BUILD_TYPE=RelWithDebInfo -DCMAKE_INSTALL_PREFIX=install -Dhistv7_benchmark=ON hist/histv7
+        run: cmake -B build -DCMAKE_BUILD_TYPE=RelWithDebInfo -DCMAKE_CXX_FLAGS="-Werror -Wall -Wextra -Wpedantic -Wsign-conversion" -DCMAKE_INSTALL_PREFIX=install -Dhistv7_benchmark=ON hist/histv7
       - name: Build
         run: cmake --build build
       - name: Install