Fix the pydebug with trace refs and count_allocs for python > 3.7

CHANGELOG.md

@@ -5,6 +5,10 @@ PyO3 versions, please see the [migration guide](https://pyo3.rs/master/migration
 The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
 and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+### Fixed
+- Stop including `Py_TRACE_REFS` config setting automatically if `Py_DEBUG` is set on Python 3.8 and up. [#1334](https://github.com/PyO3/pyo3/pull/1334)
+
 ## [0.13.0] - 2020-12-22
 ### Packaging
 - Drop support for Python 3.5 (as it is now end-of-life). [#1250](https://github.com/PyO3/pyo3/pull/1250)

build.rs

@@ -230,13 +230,17 @@ fn parse_header_defines(header_path: impl AsRef<Path>) -> Result<HashMap<String,
     Ok(definitions)
 }
 
-fn fix_config_map(mut config_map: HashMap<String, String>) -> HashMap<String, String> {
+fn fix_config_map(
+    mut config_map: HashMap<String, String>,
+    version_minor: Option<u8>,
+) -> HashMap<String, String> {
     if let Some("1") = config_map.get("Py_DEBUG").as_ref().map(|s| s.as_str()) {
         config_map.insert("Py_REF_DEBUG".to_owned(), "1".to_owned());
-        config_map.insert("Py_TRACE_REFS".to_owned(), "1".to_owned());
-        config_map.insert("COUNT_ALLOCS".to_owned(), "1".to_owned());
+        if version_minor.map_or(false, |minor| minor <= 7) {
+            // Py_DEBUG only implies Py_TRACE_REFS until Python 3.7
+            config_map.insert("Py_TRACE_REFS".to_owned(), "1".to_owned());
+        }
     }
-
     config_map
 }
 
@@ -414,7 +418,7 @@ fn load_cross_compile_from_sysconfigdata(
         calcsize_pointer,
     };
 
-    Ok((interpreter_config, fix_config_map(config_map)))
+    Ok((interpreter_config, config_map))
 }
 
 fn load_cross_compile_from_headers(
@@ -446,7 +450,7 @@ fn load_cross_compile_from_headers(
         calcsize_pointer: None,
     };
 
-    Ok((interpreter_config, fix_config_map(config_map)))
+    Ok((interpreter_config, config_map))
 }
 
 fn load_cross_compile_info(
@@ -501,7 +505,7 @@ fn get_config_vars(python_path: &Path) -> Result<HashMap<String, String>> {
             memo
         });
 
-    Ok(fix_config_map(all_vars))
+    Ok(all_vars)
 }
 
 fn get_config_vars_windows(_: &Path) -> Result<HashMap<String, String>> {
@@ -529,7 +533,7 @@ fn get_config_vars_windows(_: &Path) -> Result<HashMap<String, String>> {
     // map.insert("Py_REF_DEBUG", "1");
     // map.insert("Py_TRACE_REFS", "1");
     // map.insert("COUNT_ALLOCS", 1");
-    Ok(fix_config_map(map))
+    Ok(map)
 }
 
 fn is_value(key: &str) -> bool {
@@ -889,6 +893,7 @@ fn main() -> Result<()> {
         find_interpreter_and_get_config()?
     };
 
+    config_map = fix_config_map(config_map, interpreter_config.version.minor);
     let flags = configure(&interpreter_config)?;
 
     // These flags need to be enabled manually for PyPy, because it does not expose