erlang: exit/1 + process termination (+9 tests)

lib/erlang/runtime.sx

@@ -231,6 +231,22 @@
   er-proc-mailbox-size
   (fn (pid) (er-q-len (er-proc-field pid :mailbox))))
 
+;; Main process is always pid 0 (scheduler starts with next-pid 0 and
+;; erlang-eval-ast calls er-proc-new! first). Returns nil if no eval
+;; has run.
+(define
+  er-main-pid
+  (fn () (er-mk-pid 0)))
+
+(define
+  er-last-main-exit-reason
+  (fn
+    ()
+    (if
+      (er-proc-exists? (er-main-pid))
+      (er-proc-field (er-main-pid) :exit-reason)
+      nil)))
+
 ;; ── process BIFs ────────────────────────────────────────────────
 (define
   er-bif-is-pid
@@ -272,6 +288,20 @@
         (dict-set! proc :initial-fun fv)
         (get proc :pid)))))
 
+(define
+  er-bif-exit
+  (fn
+    (vs)
+    (cond
+      (= (len vs) 1)
+      (let
+        ((reason (nth vs 0)))
+        (shift k (er-mk-exit-marker reason)))
+      (= (len vs) 2)
+      (error
+        "Erlang: exit/2 (signal another process) deferred to Phase 4 (links)")
+      :else (error "Erlang: exit: wrong arity"))))
+
 ;; ── scheduler loop ──────────────────────────────────────────────
 ;; Each process's entry runs inside a `reset`; `receive` uses `shift`
 ;; to suspend (saving a continuation on the proc record). When a `!`
@@ -288,6 +318,18 @@
       (= (type-of v) "dict")
       (= (get v :tag) "er-suspend-marker"))))
 
+(define
+  er-exited?
+  (fn
+    (v)
+    (and
+      (= (type-of v) "dict")
+      (= (get v :tag) "er-exit-marker"))))
+
+(define
+  er-mk-exit-marker
+  (fn (reason) {:tag "er-exit-marker" :reason reason}))
+
 (define
   er-sched-run-all!
   (fn
@@ -351,6 +393,12 @@
         ((r (nth result-ref 0)))
         (cond
           (er-suspended? r) nil
+          (er-exited? r)
+          (do
+            (er-proc-set! pid :state "dead")
+            (er-proc-set! pid :exit-reason (get r :reason))
+            (er-proc-set! pid :exit-result nil)
+            (er-proc-set! pid :continuation nil))
           :else (do
             (er-proc-set! pid :state "dead")
             (er-proc-set! pid :exit-reason (er-mk-atom "normal"))

lib/erlang/tests/eval.sx

@@ -400,6 +400,38 @@
   (ev "Me = self(), Me ! first, Me ! second, X = receive second -> got_second after 0 -> to end, Y = receive first -> got_first after 0 -> to end, {X, Y}")
   (er-mk-tuple (list (er-mk-atom "got_second") (er-mk-atom "got_first"))))
 
+;; ── exit/1 + process termination ─────────────────────────────────
+(er-eval-test "exit normal returns nil" (ev "exit(normal)") nil)
+(er-eval-test "exit normal reason"
+  (do (ev "exit(normal)") (nm (er-last-main-exit-reason))) "normal")
+(er-eval-test "exit bye reason"
+  (do (ev "exit(bye)") (nm (er-last-main-exit-reason))) "bye")
+(er-eval-test "exit tuple reason"
+  (do (ev "exit({shutdown, crash})")
+    (get (er-last-main-exit-reason) :tag))
+  "tuple")
+(er-eval-test "normal completion reason"
+  (do (ev "42") (nm (er-last-main-exit-reason))) "normal")
+(er-eval-test "exit aborts subsequent"
+  (do (er-io-flush!) (ev "io:format(\"a~n\"), exit(bye), io:format(\"b~n\")") (er-io-buffer-content))
+  "a\n")
+(er-eval-test "child exit doesn't kill parent"
+  (do
+    (er-io-flush!)
+    (ev "spawn(fun () -> io:format(\"before~n\"), exit(quit), io:format(\"after~n\") end), io:format(\"main~n\")")
+    (er-io-buffer-content))
+  "main\nbefore\n")
+(er-eval-test "child exit reason recorded on child"
+  (do
+    (er-io-flush!)
+    (ev "P = spawn(fun () -> exit(child_bye) end), io:format(\"~p\", [is_pid(P)])")
+    (er-io-buffer-content))
+  "true")
+(er-eval-test "exit inside fn chain"
+  (do (ev "F = fun () -> exit(from_fn) end, F()")
+    (nm (er-last-main-exit-reason)))
+  "from_fn")
+
 (define
   er-eval-test-summary
   (str "eval " er-eval-test-pass "/" er-eval-test-count))

lib/erlang/transpile.sx

@@ -564,6 +564,7 @@
       (= name "is_pid") (er-bif-is-pid vs)
       (= name "self") (er-bif-self vs)
       (= name "spawn") (er-bif-spawn vs)
+      (= name "exit") (er-bif-exit vs)
       :else (error
         (str "Erlang: undefined function '" name "/" (len vs) "'")))))