From 4ac941a003acadfa027eb883700dff3018414267 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Erik=20Fr=C3=B6jdh?= <erik.frojdh@psi.ch>
Date: Mon, 5 Oct 2026 19:13:43 +0200
Subject: [PATCH] Add aare::ssize_t alias for MSVC (#398)

- MSVC has no ssize_t, which made every translation unit fail on
Windows.
- Define aare::ssize_t in defs.hpp: the platform ssize_t on POSIX (so
nothing changes there) and std::ptrdiff_t on MSVC.
- Code inside the namespace picks it up unchanged; the few files that
use ssize_t outside the namespace get a using-declaration. FilePtr.hpp
now includes defs.hpp since it had no aare include.

Closing #393

Co-authored-by: Claude Fable 5.1 <noreply@anthropic.com>
---
 benchmarks/fit_benchmark.cpp                    |  2 ++
 benchmarks/ndarray_benchmark.cpp                |  1 +
 include/aare/FilePtr.hpp                        |  1 +
 include/aare/defs.hpp                           | 17 +++++++++++++++++
 python/src/bind_MultiThreadedFileReader.hpp     |  1 +
 python/src/bind_calibration.hpp                 |  1 +
 python/src/fit.hpp                              |  1 +
 src/ClusterVector.test.cpp                      |  1 +
 src/MultiThreadedFileReader.test.cpp            |  1 +
 src/NDArray.test.cpp                            |  1 +
 src/NDView.test.cpp                             |  1 +
 src/algorithm.test.cpp                          |  2 ++
 src/decode.test.cpp                             |  1 +
 src/fit/Fit.test.cpp                            |  1 +
 .../PedestalTrackingPixelHistogram.test.cpp     |  1 +
 src/hist/PixelHistogram.test.cpp                |  1 +
 16 files changed, 34 insertions(+)

diff --git a/benchmarks/fit_benchmark.cpp b/benchmarks/fit_benchmark.cpp
index 8e522f80..2a307002 100644
--- a/benchmarks/fit_benchmark.cpp
+++ b/benchmarks/fit_benchmark.cpp
@@ -10,6 +10,8 @@
 #include <string>
 #include <vector>
 
+using aare::ssize_t;
+
 struct TestCase {
     std::string name;
     double true_A;
diff --git a/benchmarks/ndarray_benchmark.cpp b/benchmarks/ndarray_benchmark.cpp
index b3a3f610..46e7138e 100644
--- a/benchmarks/ndarray_benchmark.cpp
+++ b/benchmarks/ndarray_benchmark.cpp
@@ -3,6 +3,7 @@
 #include <benchmark/benchmark.h>
 
 using aare::NDArray;
+using aare::ssize_t;
 
 constexpr ssize_t size = 1024;
 class TwoArrays : public benchmark::Fixture {
diff --git a/include/aare/FilePtr.hpp b/include/aare/FilePtr.hpp
index 2e84b87c..d9753006 100644
--- a/include/aare/FilePtr.hpp
+++ b/include/aare/FilePtr.hpp
@@ -1,5 +1,6 @@
 // SPDX-License-Identifier: MPL-2.0
 #pragma once
+#include "aare/defs.hpp"
 #include <cstdio>
 #include <filesystem>
 
diff --git a/include/aare/defs.hpp b/include/aare/defs.hpp
index 174bfb6b..43cae3cb 100644
--- a/include/aare/defs.hpp
+++ b/include/aare/defs.hpp
@@ -5,6 +5,7 @@
 
 #include <array>
 #include <cassert>
+#include <cstddef>
 #include <cstdint>
 #include <cstring>
 #include <stdexcept>
@@ -13,6 +14,10 @@
 #include <variant>
 #include <vector>
 
+#if !defined(_MSC_VER)
+#include <sys/types.h> // ::ssize_t
+#endif
+
 /**
  * @brief LOCATION macro to get the current location in the code
  */
@@ -54,6 +59,18 @@
 
 namespace aare {
 
+/**
+ * Signed size and index type used throughout the library (shapes, strides,
+ * frame indices, ROI coordinates). On POSIX this is the platform's ssize_t,
+ * so nothing changes for existing code. MSVC has no ssize_t, so there it is
+ * std::ptrdiff_t, which is the same type as Py_ssize_t and NumPy's npy_intp.
+ */
+#if defined(_MSC_VER)
+using ssize_t = std::ptrdiff_t;
+#else
+using ssize_t = ::ssize_t;
+#endif
+
 inline constexpr size_t bits_per_byte = 8;
 
 void assert_failed(const std::string &msg);
diff --git a/python/src/bind_MultiThreadedFileReader.hpp b/python/src/bind_MultiThreadedFileReader.hpp
index f63f79c8..0f39cb6c 100644
--- a/python/src/bind_MultiThreadedFileReader.hpp
+++ b/python/src/bind_MultiThreadedFileReader.hpp
@@ -16,6 +16,7 @@
 #include <pybind11/stl/filesystem.h>
 
 namespace py = pybind11;
+using aare::ssize_t;
 
 inline py::dtype multi_threaded_reader_numpy_dtype(const aare::Dtype &dtype) {
     using aare::Dtype;
diff --git a/python/src/bind_calibration.hpp b/python/src/bind_calibration.hpp
index 6efa87bc..cdb16b86 100644
--- a/python/src/bind_calibration.hpp
+++ b/python/src/bind_calibration.hpp
@@ -9,6 +9,7 @@
 #include <pybind11/stl_bind.h>
 
 namespace py = pybind11;
+using aare::ssize_t;
 
 template <typename DataType>
 py::array_t<DataType>
diff --git a/python/src/fit.hpp b/python/src/fit.hpp
index f26cc20c..b41b1596 100644
--- a/python/src/fit.hpp
+++ b/python/src/fit.hpp
@@ -11,6 +11,7 @@
 
 namespace py = pybind11;
 using namespace pybind11::literals;
+using aare::ssize_t;
 
 template <typename Model>
 py::object
diff --git a/src/ClusterVector.test.cpp b/src/ClusterVector.test.cpp
index 135719c1..7d5b3910 100644
--- a/src/ClusterVector.test.cpp
+++ b/src/ClusterVector.test.cpp
@@ -12,6 +12,7 @@
 
 using aare::Cluster;
 using aare::ClusterVector;
+using aare::ssize_t;
 using C1 = Cluster<int32_t, 2, 2>;
 
 TEST_CASE("A newly created ClusterVector is empty") {
diff --git a/src/MultiThreadedFileReader.test.cpp b/src/MultiThreadedFileReader.test.cpp
index 4896d788..c6fdcd90 100644
--- a/src/MultiThreadedFileReader.test.cpp
+++ b/src/MultiThreadedFileReader.test.cpp
@@ -22,6 +22,7 @@ using aare::File;
 using aare::FileConfig;
 using aare::Frame;
 using aare::NumpyFile;
+using aare::ssize_t;
 using aare::experimental::MultiThreadedFileReader;
 
 namespace {
diff --git a/src/NDArray.test.cpp b/src/NDArray.test.cpp
index 872f22cd..56514102 100644
--- a/src/NDArray.test.cpp
+++ b/src/NDArray.test.cpp
@@ -9,6 +9,7 @@
 using aare::NDArray;
 using aare::NDView;
 using aare::Shape;
+using aare::ssize_t;
 
 TEST_CASE("Initial size is zero if no size is specified") {
     NDArray<double> a;
diff --git a/src/NDView.test.cpp b/src/NDView.test.cpp
index 1a8c6a2b..59d231b3 100644
--- a/src/NDView.test.cpp
+++ b/src/NDView.test.cpp
@@ -11,6 +11,7 @@
 using aare::NDView;
 using aare::num_elements;
 using aare::Shape;
+using aare::ssize_t;
 
 static_assert(std::is_convertible_v<NDView<int, 2>, NDView<const int, 2>>);
 static_assert(!std::is_convertible_v<NDView<const int, 2>, NDView<int, 2>>);
diff --git a/src/algorithm.test.cpp b/src/algorithm.test.cpp
index e498c3b2..026fcacb 100644
--- a/src/algorithm.test.cpp
+++ b/src/algorithm.test.cpp
@@ -3,6 +3,8 @@
 #include <aare/algorithm.hpp>
 #include <catch2/catch_test_macros.hpp>
 
+using aare::ssize_t;
+
 TEST_CASE("Find the closed index in a 1D array", "[algorithm]") {
     aare::NDArray<double, 1> arr({5});
     for (ssize_t i = 0; i < arr.size(); i++) {
diff --git a/src/decode.test.cpp b/src/decode.test.cpp
index 09d6c61c..dec59e08 100644
--- a/src/decode.test.cpp
+++ b/src/decode.test.cpp
@@ -10,6 +10,7 @@ using Catch::Matchers::WithinAbs;
 #include <vector>
 
 using aare::BitOffset;
+using aare::ssize_t;
 
 TEST_CASE("test_adc_sar_05_decode64to16") {
     uint64_t input = 0;
diff --git a/src/fit/Fit.test.cpp b/src/fit/Fit.test.cpp
index 992500e8..9c1c7311 100644
--- a/src/fit/Fit.test.cpp
+++ b/src/fit/Fit.test.cpp
@@ -17,6 +17,7 @@
 using aare::Minimizer;
 using aare::NDArray;
 using aare::NDView;
+using aare::ssize_t;
 using Catch::Approx;
 
 namespace {
diff --git a/src/hist/PedestalTrackingPixelHistogram.test.cpp b/src/hist/PedestalTrackingPixelHistogram.test.cpp
index 2c9f1590..b8d81df4 100644
--- a/src/hist/PedestalTrackingPixelHistogram.test.cpp
+++ b/src/hist/PedestalTrackingPixelHistogram.test.cpp
@@ -20,6 +20,7 @@ using aare::FileConfig;
 using aare::Frame;
 using aare::NumpyFile;
 using aare::PedestalTrackingPixelHistogram;
+using aare::ssize_t;
 
 namespace {
 
diff --git a/src/hist/PixelHistogram.test.cpp b/src/hist/PixelHistogram.test.cpp
index 50b1fcec..25767257 100644
--- a/src/hist/PixelHistogram.test.cpp
+++ b/src/hist/PixelHistogram.test.cpp
@@ -18,6 +18,7 @@
 using aare::NDArray;
 using aare::NDView;
 using aare::PixelHistogram;
+using aare::ssize_t;
 
 namespace {
 // The synchronous fill() has been removed; fill_async() is the only entry