From f60cd8a21e5e4354c1ee5059eab3823425c789d9 Mon Sep 17 00:00:00 2001
From: blueloveTH <blueloveTH@foxmail.com>
Date: Wed, 3 May 2023 16:09:37 +0800
Subject: [PATCH] fix a bug

---
 src/compiler.h   | 10 +++++-----
 tests/99_bugs.py |  9 ++++++++-
 2 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/compiler.h b/src/compiler.h
index f1928a6b..8a98486b 100644
--- a/src/compiler.h
+++ b/src/compiler.h
@@ -62,11 +62,11 @@ class Compiler {
         if(!ctx()->s_expr.empty()){
             throw std::runtime_error("!ctx()->s_expr.empty()\n" + ctx()->_log_s_expr());
         }
-        // if the last op does not return, add a default return None
-        if(ctx()->co->codes.empty() || ctx()->co->codes.back().op != OP_RETURN_VALUE){
-            ctx()->emit(OP_LOAD_NONE, BC_NOARG, BC_KEEPLINE);
-            ctx()->emit(OP_RETURN_VALUE, BC_NOARG, BC_KEEPLINE);
-        }
+        // add a `return None` in the end as a guard
+        // previously, we only do this if the last opcode is not a return
+        // however, this is buggy...since there may be a jump to the end (out of bound) even if the last opcode is a return
+        ctx()->emit(OP_LOAD_NONE, BC_NOARG, BC_KEEPLINE);
+        ctx()->emit(OP_RETURN_VALUE, BC_NOARG, BC_KEEPLINE);
         ctx()->co->optimize(vm);
         if(ctx()->co->varnames.size() > PK_MAX_CO_VARNAMES){
             SyntaxError("maximum number of local variables exceeded");
diff --git a/tests/99_bugs.py b/tests/99_bugs.py
index 9332374c..4c1eda34 100644
--- a/tests/99_bugs.py
+++ b/tests/99_bugs.py
@@ -4,4 +4,11 @@ mp = map(lambda x:  x**2, [1, 2, 3, 4, 5]  )
 assert list(mp) == [1, 4, 9, 16, 25]
 
 
-assert not 3>4
\ No newline at end of file
+assert not 3>4
+
+def f(x):
+    if x>1:
+        return 1
+
+assert f(2) == 1
+assert f(0) == None
\ No newline at end of file