gh-150907: Fix dynamic_annotations.h when built with C++ and Valgrind (#150914)

Add extern "C++" scope for the C++ template.

Fix test_cppext when Python is built with --with-valgrind.

diff --git a/Include/dynamic_annotations.h b/Include/dynamic_annotations.h
index 4d4def9bf8983e21209b598fc7cba728ca8c1d4c..5290319dd762c55c75c6ac595464cc4515632b41 100644 (file)
--- a/Include/dynamic_annotations.h
+++ b/Include/dynamic_annotations.h
@@ -461,6 +461,7 @@ int RunningOnValgrind(void);
 
 #if DYNAMIC_ANNOTATIONS_ENABLED != 0 && defined(__cplusplus)
 
+extern "C++" {
   /* _Py_ANNOTATE_UNPROTECTED_READ is the preferred way to annotate racey reads.
 
      Instead of doing
@@ -476,6 +477,8 @@ int RunningOnValgrind(void);
     _Py_ANNOTATE_IGNORE_READS_END();
     return res;
   }
+}
+
   /* Apply _Py_ANNOTATE_BENIGN_RACE_SIZED to a static variable. */
 #define _Py_ANNOTATE_BENIGN_RACE_STATIC(static_var, description)        \
     namespace {                                                       \

diff --git a/Misc/NEWS.d/next/C_API/2026-06-04-14-26-17.gh-issue-150907.CA91_B.rst b/Misc/NEWS.d/next/C_API/2026-06-04-14-26-17.gh-issue-150907.CA91_B.rst
new file mode 100644 (file)
index 0000000..f58b248
--- /dev/null
+++ b/Misc/NEWS.d/next/C_API/2026-06-04-14-26-17.gh-issue-150907.CA91_B.rst
@@ -0,0 +1,2 @@
+Fix ``dynamic_annotations.h`` header file when built with C++ and Valgrind:
+add ``extern "C++" scope`` for the C++ template. Patch by Victor Stinner.