in pep517 build default compatibility to off instead of always specifying

Changelog.md

@@ -1,5 +1,9 @@
 # Changelog
 
+## [Unreleased]
+
+* Fix usage of `--compatibility` when run as a PEP517 backend in [#1992](https://github.com/PyO3/maturin/pull/1992)
+
 ## [1.5.0] - 2024-03-05
 
 * Bump metadata version from 2.1 to 2.3 in [#1965](https://github.com/PyO3/maturin/pull/1965). Source distributions created by maturin now have reliable metadata, meaning tool such as pip, uv and poetry could skip building them for version resolution.

maturin/__init__.py

@@ -62,22 +62,26 @@ def _build_wheel(
 ) -> str:
     # PEP 517 specifies that only `sys.executable` points to the correct
     # python interpreter
-    command = [
+    base_command = [
         "maturin",
         "pep517",
         "build-wheel",
         "-i",
         sys.executable,
-        "--compatibility",
-        "off",
     ]
-    command.extend(_additional_pep517_args())
+    options = _additional_pep517_args()
     if editable:
-        command.append("--editable")
+        options.append("--editable")
 
     pep517_args = get_maturin_pep517_args(config_settings)
     if pep517_args:
-        command.extend(pep517_args)
+        options.extend(pep517_args)
+
+    if "--compatibility" not in options and "--manylinux" not in options:
+        # default to off if not otherwise specified
+        options = ["--compatibility", "off", *options]
+
+    command = [*base_command, *options]
 
     print("Running `{}`".format(" ".join(command)))
     sys.stdout.flush()