Merge #2926

2926: Warn about unknown config keys in `PYO3_CONFIG_FILE` r=davidhewitt a=messense

`maturin` also read from `PYO3_CONFIG_FILE` to get `ext_suffix` config, `pyo3-build-config` currently denies unknown config keys makes it inconvenient.

See PyO3/maturin#1430

Co-authored-by: messense <[email protected]>

newsfragments/2926.changed.md

@@ -0,0 +1 @@
+Warn about unknown config keys in `PYO3_CONFIG_FILE` instead of denying.

pyo3-build-config/src/errors.rs

@@ -19,6 +19,9 @@ macro_rules! warn {
     ($msg: literal) => {
         println!(concat!("cargo:warning=", $msg))
     };
+    ($fmt: expr, $($args: tt)+) => {
+        println!("cargo:warning={}", format_args!($fmt, $($args)+))
+    };
 }
 
 /// A simple error implementation which allows chaining of errors, inspired somewhat by anyhow.

pyo3-build-config/src/impl_.rs

@@ -433,7 +433,7 @@ print("mingw", get_platform().startswith("mingw"))
                 "extra_build_script_line" => {
                     extra_build_script_lines.push(value.to_string());
                 }
-                unknown => bail!("unknown config key `{}`", unknown),
+                unknown => warn!("unknown config key `{}`", unknown),
             }
         }
 
@@ -1865,6 +1865,28 @@ mod tests {
         )
     }
 
+    #[test]
+    fn test_config_file_unknown_keys() {
+        // ext_suffix is unknown to pyo3-build-config, but it shouldn't error
+        assert_eq!(
+            InterpreterConfig::from_reader("version=3.7\next_suffix=.python37.so".as_bytes())
+                .unwrap(),
+            InterpreterConfig {
+                version: PythonVersion { major: 3, minor: 7 },
+                implementation: PythonImplementation::CPython,
+                shared: true,
+                abi3: false,
+                lib_name: None,
+                lib_dir: None,
+                executable: None,
+                pointer_width: None,
+                build_flags: BuildFlags::default(),
+                suppress_build_script_link_lines: false,
+                extra_build_script_lines: vec![],
+            }
+        )
+    }
+
     #[test]
     fn build_flags_default() {
         assert_eq!(BuildFlags::default(), BuildFlags::new());