From 60c2a1b4b86fe20601dd910a9699f1718838e7f0 Mon Sep 17 00:00:00 2001
From: Charlotte <charlotte@hrzn.ee>
Date: Thu, 29 Jun 2023 11:15:31 +1000
Subject: [PATCH] sim._pyrtl: don't blow parser stack on older Pythons.

Python pre-3.9 can't handle parentheses nested this deeply.

* https://github.com/amaranth-lang/amaranth/pull/681 -- motivating
  example.
* https://github.com/amaranth-lang/amaranth/pull/827 -- what added
  enough extra parentheses to make this only break now.
* https://peps.python.org/pep-0617/ -- new parser as of 3.9.
---
 amaranth/sim/_pyrtl.py | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/amaranth/sim/_pyrtl.py b/amaranth/sim/_pyrtl.py
index d9787ff..0fa23af 100644
--- a/amaranth/sim/_pyrtl.py
+++ b/amaranth/sim/_pyrtl.py
@@ -83,7 +83,11 @@ class _ValueCompiler(ValueVisitor, _Compiler):
                                 "simulate in reasonable time"
                                 .format(src, len(value)))
 
-        return super().on_value(value)
+        v = super().on_value(value)
+        if isinstance(v, str) and len(v) > 1000:
+            # Avoid parser stack overflow on older Pythons.
+            return self.emitter.def_var("intermediate", v)
+        return v
 
     def on_ClockSignal(self, value):
         raise NotImplementedError # :nocov: