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pythongh-121617: Include <string.h> for Py_CLEAR() macro
If the _Py_TYPEOF macro is not available, include <string.h> to get memcpy() for the Py_CLEAR() macro. The limited C API version 3.11 and newer doesn't include <string.h> anymore. Add a Py_CLEAR() test in test_cext. Modify also _Py_TYPEOF to use C23 typeof() if available.
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Lines changed: 15 additions & 2 deletions

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‎Include/pyport.h‎

Lines changed: 5 additions & 2 deletions
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@@ -567,8 +567,11 @@ extern "C" {
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//
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// Example: _Py_TYPEOF(x) x_copy = (x);
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//
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// The macro is only defined if GCC or clang compiler is used.
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#if defined(__GNUC__) || defined(__clang__)
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// On C23, use typeof(). Otherwise, the macro is only defined
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// if GCC or clang compiler is used.
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#if defined (__STDC_VERSION__) && __STDC_VERSION__ >= 202311L
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# define _Py_TYPEOF(expr) typeof(expr)
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#elif defined(__GNUC__) || defined(__clang__)
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# define _Py_TYPEOF(expr) __typeof__(expr)
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#endif
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‎Include/refcount.h‎

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@@ -471,6 +471,9 @@ static inline Py_ALWAYS_INLINE void Py_DECREF(PyObject *op)
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* and so avoid type punning. Otherwise, use memcpy() which causes type erasure
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* and so prevents the compiler to reuse an old cached 'op' value after
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* Py_CLEAR().
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*
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* Include <string.h> if _Py_TYPEOF() is not available, since the limited C API
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* version 3.11 and newer doesn't include it.
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*/
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#ifdef _Py_TYPEOF
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#define Py_CLEAR(op) \
@@ -483,6 +486,7 @@ static inline Py_ALWAYS_INLINE void Py_DECREF(PyObject *op)
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} \
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} while (0)
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#else
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#include <string.h> // memcpy()
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#define Py_CLEAR(op) \
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do { \
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PyObject **_tmp_op_ptr = _Py_CAST(PyObject**, &(op)); \

‎Lib/test/test_cext/extension.c‎

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Original file line numberDiff line numberDiff line change
@@ -65,6 +65,8 @@ _testcext_exec(
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#endif
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)
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{
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PyObject *obj;
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#ifdef __STDC_VERSION__
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if (PyModule_AddIntMacro(module, __STDC_VERSION__) < 0) {
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return -1;
@@ -75,6 +77,10 @@ _testcext_exec(
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Py_BUILD_ASSERT(sizeof(int) == sizeof(unsigned int));
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assert(Py_BUILD_ASSERT_EXPR(sizeof(int) == sizeof(unsigned int)) == 0);
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// Test Py_CLEAR()
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obj = NULL;
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Py_CLEAR(obj);
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return 0;
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}
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