From 029b157540f18b81bad38c92d666b6414b3ef547 Mon Sep 17 00:00:00 2001
From: "Ralf W. Grosse-Kunstleve" <rwgk@google.com>
Date: Thu, 18 May 2023 23:28:53 -0700
Subject: [PATCH] Add `buffer_info::compare<T>` to make
 `detail::compare_buffer_info<T>::compare` more visible & accessible.

---
 include/pybind11/buffer_info.h | 10 +++++++++-
 tests/test_buffers.cpp         |  4 ++--
 tests/test_buffers.py          |  4 ++--
 3 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/include/pybind11/buffer_info.h b/include/pybind11/buffer_info.h
index 06120d5563..f8689babf3 100644
--- a/include/pybind11/buffer_info.h
+++ b/include/pybind11/buffer_info.h
@@ -37,6 +37,9 @@ inline std::vector<ssize_t> f_strides(const std::vector<ssize_t> &shape, ssize_t
     return strides;
 }
 
+template <typename T, typename SFINAE = void>
+struct compare_buffer_info;
+
 PYBIND11_NAMESPACE_END(detail)
 
 /// Information record describing a Python buffer object
@@ -150,6 +153,11 @@ struct buffer_info {
     Py_buffer *view() const { return m_view; }
     Py_buffer *&view() { return m_view; }
 
+    template <typename T>
+    static bool compare(const buffer_info &b) {
+        return detail::compare_buffer_info<T>::compare(b);
+    }
+
 private:
     struct private_ctr_tag {};
 
@@ -170,7 +178,7 @@ struct buffer_info {
 
 PYBIND11_NAMESPACE_BEGIN(detail)
 
-template <typename T, typename SFINAE = void>
+template <typename T, typename SFINAE>
 struct compare_buffer_info {
     static bool compare(const buffer_info &b) {
         return b.format == format_descriptor<T>::format() && b.itemsize == (ssize_t) sizeof(T);
diff --git a/tests/test_buffers.cpp b/tests/test_buffers.cpp
index ed9013ae7b..ab727552f4 100644
--- a/tests/test_buffers.cpp
+++ b/tests/test_buffers.cpp
@@ -16,7 +16,7 @@
 TEST_SUBMODULE(buffers, m) {
     m.attr("std_is_same_double_long_double") = std::is_same<double, long double>::value;
 
-    m.def("format_descriptor_format_compare",
+    m.def("format_descriptor_format_buffer_info_compare",
           [](const std::string &cpp_name, const py::buffer &buffer) {
               // https://google.github.io/styleguide/cppguide.html#Static_and_Global_Variables
               static auto *format_table = new std::map<std::string, std::string>;
@@ -25,7 +25,7 @@ TEST_SUBMODULE(buffers, m) {
               if (format_table->empty()) {
 #define PYBIND11_ASSIGN_HELPER(...)                                                               \
     (*format_table)[#__VA_ARGS__] = py::format_descriptor<__VA_ARGS__>::format();                 \
-    (*compare_table)[#__VA_ARGS__] = py::detail::compare_buffer_info<__VA_ARGS__>::compare;
+    (*compare_table)[#__VA_ARGS__] = py::buffer_info::compare<__VA_ARGS__>;
                   PYBIND11_ASSIGN_HELPER(PyObject *)
                   PYBIND11_ASSIGN_HELPER(bool)
                   PYBIND11_ASSIGN_HELPER(std::int8_t)
diff --git a/tests/test_buffers.py b/tests/test_buffers.py
index 108154231a..4a60ea4261 100644
--- a/tests/test_buffers.py
+++ b/tests/test_buffers.py
@@ -48,10 +48,10 @@
 
 
 @pytest.mark.parametrize(("cpp_name", "np_dtype"), CPP_NAME_NP_DTYPE_TABLE)
-def test_format_descriptor_format_compare(cpp_name, np_dtype):
+def test_format_descriptor_format_buffer_info_compare(cpp_name, np_dtype):
     np_array = np.array([], dtype=np_dtype)
     for other_cpp_name, expected_format in CPP_NAME_FORMAT_TABLE:
-        format, np_array_is_matching = m.format_descriptor_format_compare(
+        format, np_array_is_matching = m.format_descriptor_format_buffer_info_compare(
             other_cpp_name, np_array
         )
         assert format == expected_format