From b1a0b36582a0daab85325bbc8ed98d42cce13c03 Mon Sep 17 00:00:00 2001
From: Wanda <wanda@phinode.net>
Date: Tue, 6 Feb 2024 19:43:47 +0100
Subject: [PATCH] sim: fix simulation loop when process catches an injected
 exception.

---
 amaranth/sim/_pycoro.py | 21 ++++++++++++++-------
 tests/test_sim.py       |  1 -
 2 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/amaranth/sim/_pycoro.py b/amaranth/sim/_pycoro.py
index e9500c47f..6a0487e6b 100644
--- a/amaranth/sim/_pycoro.py
+++ b/amaranth/sim/_pycoro.py
@@ -59,12 +59,23 @@ def run(self):
         self.clear_triggers()
 
         response = None
+        exception = None
         while True:
             try:
-                command = self.coroutine.send(response)
+                if exception is None:
+                    command = self.coroutine.send(response)
+                else:
+                    command = self.coroutine.throw(exception)
+            except StopIteration:
+                self.passive = True
+                self.coroutine = None
+                return
+
+            try:
                 if command is None:
                     command = self.default_cmd
                 response = None
+                exception = None
 
                 if isinstance(command, ValueCastable):
                     command = Value.cast(command)
@@ -118,10 +129,6 @@ def run(self):
                     raise TypeError("Received unsupported command {!r} from process {!r}"
                                     .format(command, self.src_loc()))
 
-            except StopIteration:
-                self.passive = True
-                self.coroutine = None
-                return
-
             except Exception as exn:
-                self.coroutine.throw(exn)
+                response = None
+                exception = exn
diff --git a/tests/test_sim.py b/tests/test_sim.py
index 5614259dd..5eaf6df35 100644
--- a/tests/test_sim.py
+++ b/tests/test_sim.py
@@ -685,7 +685,6 @@ def process():
                 with self.assertRaisesRegex(TypeError,
                         r"Received unsupported command 1 from process .+?"):
                     yield 1
-                yield Settle()
                 survived = True
             sim.add_process(process)
         self.assertTrue(survived)