esp_macro: Fix CHOOSE_MACRO_VA_ARG() for C++20

Closes https://github.com/espressif/esp-idf/pull/8372
Closes https://github.com/espressif/esp-idf/issues/8371

[darian@espressif.com: Updated macro description and commit message]
Signed-off-by: Darian Leung <darian@espressif.com>

components/esp_common/include/esp_macro.h

@@ -22,24 +22,53 @@ extern "C" {
  *
  * "CHOOSE_MACRO_VA_ARG" make use of the fact that "##__VA_ARGS__," will eliminate the trailing comma if there are no
  * arguments, thus allows subsequent arguments in "CHOOSE_MACRO_VA_ARG" to be left shifted in the parameter list.
- * Therefore, if we call "CHOOSE_MACRO_VA_ARG(_0, ##__VA_ARGS__, MACRO1, MACRO2)(__VA_ARGS__)", the result will be:
  *
- * - MACRO1(__VA_ARGS__) if __VA_ARGS__ was not empty
- * - MACRO2() if __VA_ARGS__ was empty
+ * Therefore, if we call the following:
+ * - CHOOSE_MACRO_VA_ARG(MACRO_ARGS, MACRO_NO_ARGS, ##__VA_ARGS__)(__VA_ARGS__)
+ *
+ * The result will be:
+ * - MACRO_ARGS(__VA_ARGS__) if __VA_ARGS__ was not empty
+ * - MACRO_NO_ARGS() if __VA_ARGS__ was empty
  *
  * @note In the future, we want to switch to C++20. We also want to become compatible with clang. Hence, we provide two
- * versions of the following macros which are using variadic arguments. The first one is using the GNU extension
- * ##__VA_ARGS__. The second one is using the C++20 feature __VA_OPT__(,). This allows users to compile their code with
- * standard C++20 enabled instead of the GNU extension. Below C++20, we haven't found any good alternative to using
- * ##__VA_ARGS__.
+ * versions of the following macros which are using variadic arguments. One is using the GNU extension ##__VA_ARGS__.
+ * The other is using the C++20 feature __VA_OPT__(,). This allows users to compile their code with standard C++20
+ * enabled instead of the GNU extension. Below C++20, we haven't found any good alternative to using ##__VA_ARGS__.
  */
 #if defined(__cplusplus) && (__cplusplus >  201703L)
-#define CHOOSE_MACRO_VA_ARG(_0 __VA_OPT__(,) __VA_ARGS__, MACRO, ...) MACRO
+#define CHOOSE_MACRO_VA_ARG_INN_IMPL(...) __VA_OPT__(0)
+#define CHOOSE_MACRO_VA_ARG_INN(one, MACRO1, MACRO2, ...) MACRO1
+#define CHOOSE_MACRO_VA_ARG(MACRO_WITH_ARGS, MACRO_WITH_NO_ARGS, ...) CHOOSE_MACRO_VA_ARG_INN(CHOOSE_MACRO_VA_ARG_INN_IMPL(__VA_ARGS__) __VA_OPT__(,) MACRO_WITH_ARGS, MACRO_WITH_NO_ARGS, 0)
+#else
+#define CHOOSE_MACRO_VA_ARG_INN(one, two, MACRO1, MACRO2, ...) MACRO1
+#define CHOOSE_MACRO_VA_ARG(MACRO_WITH_ARGS, MACRO_WITH_NO_ARGS, ...) CHOOSE_MACRO_VA_ARG_INN(0, ##__VA_ARGS__, MACRO_WITH_ARGS, MACRO_WITH_NO_ARGS, 0)
+#endif
+
+/* test macros */
+#define foo_args(...) 1
+#define foo_no_args() 2
+#if defined(__cplusplus) && (__cplusplus >  201703L)
+#define foo(...) CHOOSE_MACRO_VA_ARG(foo_args, foo_no_args __VA_OPT__(,) __VA_ARGS__)(__VA_ARGS__)
+#else
+#define foo(...) CHOOSE_MACRO_VA_ARG(foo_args, foo_no_args, ##__VA_ARGS__)(__VA_ARGS__)
+#endif
+
+#if defined(__cplusplus)
+#define MY_STATIC_ASSERT static_assert
 #else
-#define CHOOSE_MACRO_VA_ARG(_0, _1, MACRO, ...) MACRO
+#define MY_STATIC_ASSERT _Static_assert
+#endif
+
+MY_STATIC_ASSERT(foo() == 2, "CHOOSE_MACRO_VA_ARG() result does not match for 0 arguments");
+MY_STATIC_ASSERT(foo(42) == 1, "CHOOSE_MACRO_VA_ARG() result does not match for 1 argument");
+#if defined(__cplusplus) && (__cplusplus >  201703L)
+static_assert(foo(42, 87) == 1, "CHOOSE_MACRO_VA_ARG() result does not match for n arguments");
 #endif
-_Static_assert(CHOOSE_MACRO_VA_ARG(_0, x, 0, 1) == 0, "CHOOSE_MACRO_VA_ARG() result does not match for 0 arguments");
-_Static_assert(CHOOSE_MACRO_VA_ARG(_0, 0, 1) == 1, "CHOOSE_MACRO_VA_ARG() result does not match for 1 argument");
+
+#undef MY_STATIC_ASSERT
+#undef foo
+#undef foo_args
+#undef foo_no_args
 
 #ifdef __cplusplus
 }

components/freertos/FreeRTOS-Kernel-SMP/portable/xtensa/include/freertos/portmacro.h

@@ -170,8 +170,13 @@ extern void vTaskExitCritical( void );
 #define portENTER_CRITICAL_SMP()                    vTaskEnterCritical();
 #define portEXIT_CRITICAL_SMP()                     vTaskExitCritical();
 
-#define portENTER_CRITICAL(...)                     CHOOSE_MACRO_VA_ARG(_0, ##__VA_ARGS__, portENTER_CRITICAL_IDF, portENTER_CRITICAL_SMP)(__VA_ARGS__)
-#define portEXIT_CRITICAL(...)                      CHOOSE_MACRO_VA_ARG(_0, ##__VA_ARGS__, portEXIT_CRITICAL_IDF, portEXIT_CRITICAL_SMP)(__VA_ARGS__)
+#if defined(__cplusplus) && (__cplusplus >  201703L)
+#define portENTER_CRITICAL(...)                     CHOOSE_MACRO_VA_ARG(portENTER_CRITICAL_IDF, portENTER_CRITICAL_SMP __VA_OPT__(,) __VA_ARGS__)(__VA_ARGS__)
+#define portEXIT_CRITICAL(...)                      CHOOSE_MACRO_VA_ARG(portEXIT_CRITICAL_IDF, portEXIT_CRITICAL_SMP __VA_OPT__(,) __VA_ARGS__)(__VA_ARGS__)
+#else
+#define portENTER_CRITICAL(...)                     CHOOSE_MACRO_VA_ARG(portENTER_CRITICAL_IDF, portENTER_CRITICAL_SMP, ##__VA_ARGS__)(__VA_ARGS__)
+#define portEXIT_CRITICAL(...)                      CHOOSE_MACRO_VA_ARG(portEXIT_CRITICAL_IDF, portEXIT_CRITICAL_SMP, ##__VA_ARGS__)(__VA_ARGS__)
+#endif
 
 #define portSET_INTERRUPT_MASK_FROM_ISR() ({ \
     unsigned int cur_level; \
@@ -188,7 +193,11 @@ extern void vTaskExitCritical( void );
 // ---------------------- Yielding -------------------------
 
 #define portYIELD()                                 vPortYield()
-#define portYIELD_FROM_ISR(...)                     CHOOSE_MACRO_VA_ARG(_0, ##__VA_ARGS__, portYIELD_FROM_ISR_CHECK, portYIELD_FROM_ISR_NO_CHECK)(__VA_ARGS__)
+#if defined(__cplusplus) && (__cplusplus >  201703L)
+#define portYIELD_FROM_ISR(...)                     CHOOSE_MACRO_VA_ARG(portYIELD_FROM_ISR_CHECK, portYIELD_FROM_ISR_NO_CHECK __VA_OPT__(,) __VA_ARGS__)(__VA_ARGS__)
+#else
+#define portYIELD_FROM_ISR(...)                     CHOOSE_MACRO_VA_ARG(portYIELD_FROM_ISR_CHECK, portYIELD_FROM_ISR_NO_CHECK, ##__VA_ARGS__)(__VA_ARGS__)
+#endif
 #define portYIELD_CORE(x)                           vPortYieldCore(x)
 
 // ----------------------- System --------------------------

components/freertos/FreeRTOS-Kernel/portable/riscv/include/freertos/portmacro.h

@@ -391,9 +391,9 @@ static inline BaseType_t IRAM_ATTR xPortGetCoreID(void)
  *          might result in undesired behavior
  */
 #if defined(__cplusplus) && (__cplusplus >  201703L)
-#define portYIELD_FROM_ISR(...) CHOOSE_MACRO_VA_ARG(_0 __VA_OPT__(,) ##__VA_ARGS__, portYIELD_FROM_ISR_ARG, portYIELD_FROM_ISR_NO_ARG)(__VA_ARGS__)
+#define portYIELD_FROM_ISR(...) CHOOSE_MACRO_VA_ARG(portYIELD_FROM_ISR_ARG, portYIELD_FROM_ISR_NO_ARG __VA_OPT__(,) __VA_ARGS__)(__VA_ARGS__)
 #else
-#define portYIELD_FROM_ISR(...) CHOOSE_MACRO_VA_ARG(_0, ##__VA_ARGS__, portYIELD_FROM_ISR_ARG, portYIELD_FROM_ISR_NO_ARG)(__VA_ARGS__)
+#define portYIELD_FROM_ISR(...) CHOOSE_MACRO_VA_ARG(portYIELD_FROM_ISR_ARG, portYIELD_FROM_ISR_NO_ARG, ##__VA_ARGS__)(__VA_ARGS__)
 #endif
 
 

components/freertos/FreeRTOS-Kernel/portable/xtensa/include/freertos/portmacro.h

@@ -524,9 +524,9 @@ extern void _frxt_setup_switch( void );     //Defined in portasm.S
  *          might result in undesired behavior
  */
 #if defined(__cplusplus) && (__cplusplus >  201703L)
-#define portYIELD_FROM_ISR(...) CHOOSE_MACRO_VA_ARG(_0 __VA_OPT__(,) ##__VA_ARGS__, portYIELD_FROM_ISR_ARG, portYIELD_FROM_ISR_NO_ARG)(__VA_ARGS__)
+#define portYIELD_FROM_ISR(...) CHOOSE_MACRO_VA_ARG(portYIELD_FROM_ISR_ARG, portYIELD_FROM_ISR_NO_ARG __VA_OPT__(,) __VA_ARGS__)(__VA_ARGS__)
 #else
-#define portYIELD_FROM_ISR(...) CHOOSE_MACRO_VA_ARG(_0, ##__VA_ARGS__, portYIELD_FROM_ISR_ARG, portYIELD_FROM_ISR_NO_ARG)(__VA_ARGS__)
+#define portYIELD_FROM_ISR(...) CHOOSE_MACRO_VA_ARG(portYIELD_FROM_ISR_ARG, portYIELD_FROM_ISR_NO_ARG, ##__VA_ARGS__)(__VA_ARGS__)
 #endif
 
 /* Yielding within an API call (when interrupts are off), means the yield should be delayed