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 <[email protected]>

Author: pi-anl

ports/unix/main.c

@@ -236,6 +236,17 @@ 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) {
@@ -245,6 +256,7 @@ 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