Merge pull request #2727 from messense/pyo3-rebuild

`pyo3-build-config`: rebuild when `PYO3_ENVIRONMENT_SIGNATURE` value changed

guide/src/building_and_distribution.md

@@ -45,6 +45,8 @@ Caused by:
   suppress_build_script_link_lines=false
 ```
 
+The `PYO3_ENVIRONMENT_SIGNATURE` environment variable can be used to trigger rebuilds when its value changes, it has no other effect.
+
 ### Advanced: config files
 
 If you save the above output config from `PYO3_PRINT_CONFIG` to a file, it is possible to manually override the contents and feed it back into PyO3 using the `PYO3_CONFIG_FILE` env var.

newsfragments/2727.added.md

@@ -0,0 +1 @@
+`pyo3-build-config`: rebuild when `PYO3_ENVIRONMENT_SIGNATURE` environment variable value changed

pyo3-build-config/src/impl_.rs

@@ -1684,6 +1684,10 @@ fn get_env_interpreter() -> Option<PathBuf> {
 ///   3. `python`, if this is functional a Python 3.x interpreter
 ///   4. `python3`, as above
 pub fn find_interpreter() -> Result<PathBuf> {
+    // Trigger rebuilds when `PYO3_ENVIRONMENT_SIGNATURE` env var value changes
+    // See https://github.com/PyO3/pyo3/issues/2724
+    println!("cargo:rerun-if-env-changed=PYO3_ENVIRONMENT_SIGNATURE");
+
     if let Some(exe) = env_var("PYO3_PYTHON") {
         Ok(exe.into())
     } else if let Some(env_interpreter) = get_env_interpreter() {