Introducing PYBIND11_VERSION_HEX (#3120)

* Introducing PYBIND11_VERSION_HEX (better late than never!)

* PYBIND11_VERSION_HEX consistency check in setup.py

include/pybind11/detail/common.h

@@ -13,6 +13,10 @@
 #define PYBIND11_VERSION_MINOR 6
 #define PYBIND11_VERSION_PATCH 3.dev1
 
+// Similar to Python's convention: https://docs.python.org/3/c-api/apiabiversion.html
+// Additional convention: 0xD = dev
+#define PYBIND11_VERSION_HEX 0x020603D1
+
 #define PYBIND11_NAMESPACE_BEGIN(name) namespace name {
 #define PYBIND11_NAMESPACE_END(name) }
 

setup.py

@@ -19,6 +19,36 @@ VERSION_REGEX = re.compile(
     r"^\s*#\s*define\s+PYBIND11_VERSION_([A-Z]+)\s+(.*)$", re.MULTILINE
 )
 
+
+def build_expected_version_hex(matches):
+    patch_level_serial = matches["PATCH"]
+    serial = None
+    try:
+        major = int(matches["MAJOR"])
+        minor = int(matches["MINOR"])
+        flds = patch_level_serial.split(".")
+        if flds:
+            patch = int(flds[0])
+            level = None
+            if len(flds) == 1:
+                level = "0"
+                serial = 0
+            elif len(flds) == 2:
+                level_serial = flds[1]
+                for level in ("a", "b", "c", "dev"):
+                    if level_serial.startswith(level):
+                        serial = int(level_serial[len(level) :])
+                        break
+    except ValueError:
+        pass
+    if serial is None:
+        msg = 'Invalid PYBIND11_VERSION_PATCH: "{}"'.format(patch_level_serial)
+        raise RuntimeError(msg)
+    return "0x{:02x}{:02x}{:02x}{}{:x}".format(
+        major, minor, patch, level[:1].upper(), serial
+    )
+
+
 # PYBIND11_GLOBAL_SDIST will build a different sdist, with the python-headers
 # files, and the sys.prefix files (CMake and headers).
 
@@ -49,6 +79,15 @@ if version != cpp_version:
     )
     raise RuntimeError(msg)
 
+version_hex = matches.get("HEX", "MISSING")
+expected_version_hex = build_expected_version_hex(matches)
+if version_hex != expected_version_hex:
+    msg = "PYBIND11_VERSION_HEX {} does not match expected value {}!".format(
+        version_hex,
+        expected_version_hex,
+    )
+    raise RuntimeError(msg)
+
 
 def get_and_replace(filename, binary=False, **opts):
     with open(filename, "rb" if binary else "r") as f: