unix: Enable exit code handling for sys.exit().

Enable `MICROPY_PYEXEC_ENABLE_EXIT_CODE_HANDLING` to propagate `sys.exit()`
exit codes properly. Update `convert_pyexec_result()` to handle return
values where pyexec returns the exit code with `PYEXEC_FORCED_EXIT` flag
set for `SystemExit`. Extract the exit code from the lower 8 bits when the
flag is set, otherwise return as-is (0 for success, 1 for exception).

Signed-off-by: Andrew Leech <andrew.leech@planetinnovation.com.au>

Author: pi-anl

ports/unix/main.c

@@ -242,6 +242,17 @@ static int do_repl(void) {
 }
 
 static inline int convert_pyexec_result(int ret) {
+    #if MICROPY_PYEXEC_ENABLE_EXIT_CODE_HANDLING
+    // With exit code handling enabled:
+    // pyexec returns exit code with PYEXEC_FORCED_EXIT flag set for SystemExit
+    // Unix port expects: 0 for success, non-zero for error/exit
+    if (ret & PYEXEC_FORCED_EXIT) {
+        // SystemExit: extract exit code from lower bits
+        return ret & 0xFF;
+    }
+    // Normal execution or exception: return as-is (0 for success, 1 for exception)
+    return ret;
+    #else
     // pyexec returns 1 for success, 0 for exception, PYEXEC_FORCED_EXIT for SystemExit
     // Convert to unix port's expected codes: 0 for success, 1 for exception, FORCED_EXIT|val for SystemExit
     if (ret == 1) {
@@ -251,6 +262,7 @@ static inline int convert_pyexec_result(int ret) {
     } else {
         return 1; // exception
     }
+    #endif
 }
 
 static int do_file(const char *file) {

ports/unix/mpconfigport.h

@@ -154,6 +154,9 @@ typedef long mp_off_t;
 // Enable support for compile-only mode.
 #define MICROPY_PYEXEC_COMPILE_ONLY (1)
 
+// Enable handling of sys.exit() exit codes.
+#define MICROPY_PYEXEC_ENABLE_EXIT_CODE_HANDLING (1)
+
 #define MICROPY_PY_SOCKET_LISTEN_BACKLOG_DEFAULT (SOMAXCONN < 128 ? SOMAXCONN : 128)
 
 // Bare-metal ports don't have stderr. Printing debug to stderr may give tests

ports/windows/mpconfigport.h

@@ -164,6 +164,9 @@
 // Enable support for compile-only mode.
 #define MICROPY_PYEXEC_COMPILE_ONLY (1)
 
+// Enable handling of sys.exit() exit codes.
+#define MICROPY_PYEXEC_ENABLE_EXIT_CODE_HANDLING (1)
+
 #define MICROPY_ERROR_REPORTING     (MICROPY_ERROR_REPORTING_DETAILED)
 #define MICROPY_ERROR_PRINTER       (&mp_stderr_print)
 #define MICROPY_WARNINGS            (1)

shared/runtime/pyexec.c

@@ -165,6 +165,7 @@ static int parse_compile_execute(const void *source, mp_parse_input_kind_t input
         #endif
         if (mp_obj_is_subclass_fast(MP_OBJ_FROM_PTR(((mp_obj_base_t *)nlr.ret_val)->type), MP_OBJ_FROM_PTR(&mp_type_SystemExit))) { // system exit
             #if MICROPY_PYEXEC_ENABLE_EXIT_CODE_HANDLING
+            // None is an exit value of 0; an int is its value; anything else is 1
             mp_obj_t val = mp_obj_exception_get_value(MP_OBJ_FROM_PTR(nlr.ret_val));
             if (val != mp_const_none) {
                 if (mp_obj_is_int(val)) {