From 9b6511cd55b74f42ba1c8db4a9cf15a5211550b7 Mon Sep 17 00:00:00 2001
From: "Ralf W. Grosse-Kunstleve" <rwgk@google.com>
Date: Wed, 6 Jul 2022 15:49:09 -0700
Subject: [PATCH 1/2] Report `C++ Info:` from `pytest_configure()`

---
 include/pybind11/detail/common.h |  1 +
 tests/conftest.py                | 12 +++++++++++-
 tests/pybind11_tests.cpp         | 25 +++++++++++++++++++++++++
 3 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/include/pybind11/detail/common.h b/include/pybind11/detail/common.h
index 9355ecfda0..e52507a9e8 100644
--- a/include/pybind11/detail/common.h
+++ b/include/pybind11/detail/common.h
@@ -38,6 +38,7 @@
 #            define PYBIND11_CPP17
 #            if __cplusplus >= 202002L
 #                define PYBIND11_CPP20
+// Please update tests/pybind11_tests.cpp `cpp_std()` when adding a macro here.
 #            endif
 #        endif
 #    endif
diff --git a/tests/conftest.py b/tests/conftest.py
index e72ec0ef81..d648997345 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -13,7 +13,7 @@
 import pytest
 
 # Early diagnostic for failed imports
-import pybind11_tests  # noqa: F401
+import pybind11_tests
 
 _long_marker = re.compile(r"([0-9])L")
 _hexadecimal = re.compile(r"0x[0-9a-fA-F]+")
@@ -196,5 +196,15 @@ def gc_collect():
 
 
 def pytest_configure():
+    print(
+        "C++ Info:",
+        pybind11_tests.compiler_info,
+        pybind11_tests.cpp_std,
+        pybind11_tests.PYBIND11_INTERNALS_ID,
+        flush=True,
+    )
+    assert (
+        pybind11_tests.compiler_info is not None
+    ), "Please update pybind11_tests.cpp if this assert fails."
     pytest.suppress = suppress
     pytest.gc_collect = gc_collect
diff --git a/tests/pybind11_tests.cpp b/tests/pybind11_tests.cpp
index 3c04699157..aa3095594b 100644
--- a/tests/pybind11_tests.cpp
+++ b/tests/pybind11_tests.cpp
@@ -62,9 +62,34 @@ void bind_ConstructorStats(py::module_ &m) {
         });
 }
 
+const char *cpp_std() {
+    return
+#if defined(PYBIND11_CPP20)
+        "C++20";
+#elif defined(PYBIND11_CPP17)
+        "C++17";
+#elif defined(PYBIND11_CPP14)
+        "C++14";
+#else
+        "C++11";
+#endif
+}
+
 PYBIND11_MODULE(pybind11_tests, m) {
     m.doc() = "pybind11 test module";
 
+    // Intentionally kept minimal to not create a maintenance chore
+    // ("just enough" to be conclusive).
+#if defined(_MSC_FULL_VER)
+    m.attr("compiler_info") = "MSVC " PYBIND11_TOSTRING(_MSC_FULL_VER);
+#elif defined(__VERSION__)
+    m.attr("compiler_info") = __VERSION__;
+#else
+    m.attr("compiler_info") = py::none();
+#endif
+    m.attr("cpp_std") = cpp_std();
+    m.attr("PYBIND11_INTERNALS_ID") = PYBIND11_INTERNALS_ID;
+
     bind_ConstructorStats(m);
 
 #if defined(PYBIND11_DETAILED_ERROR_MESSAGES)

From a934f8e5ddbce0d944ddb08329e8edae137b43e0 Mon Sep 17 00:00:00 2001
From: "Ralf W. Grosse-Kunstleve" <rwgk@google.com>
Date: Thu, 7 Jul 2022 11:11:15 -0700
Subject: [PATCH 2/2] Use pytest_report_header() as suggested by @skylion007

---
 tests/conftest.py | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/tests/conftest.py b/tests/conftest.py
index d648997345..02ce263afc 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -196,15 +196,18 @@ def gc_collect():
 
 
 def pytest_configure():
-    print(
-        "C++ Info:",
-        pybind11_tests.compiler_info,
-        pybind11_tests.cpp_std,
-        pybind11_tests.PYBIND11_INTERNALS_ID,
-        flush=True,
-    )
+    pytest.suppress = suppress
+    pytest.gc_collect = gc_collect
+
+
+def pytest_report_header(config):
+    del config  # Unused.
     assert (
         pybind11_tests.compiler_info is not None
     ), "Please update pybind11_tests.cpp if this assert fails."
-    pytest.suppress = suppress
-    pytest.gc_collect = gc_collect
+    return (
+        "C++ Info:"
+        f" {pybind11_tests.compiler_info}"
+        f" {pybind11_tests.cpp_std}"
+        f" {pybind11_tests.PYBIND11_INTERNALS_ID}"
+    )