From 30ab196fdc73390a3cd6d8d81c0e7638fac5b75a Mon Sep 17 00:00:00 2001
From: joshua1b <joshua1b2823@gmail.com>
Date: Sat, 2 Nov 2019 23:47:44 +0900
Subject: [PATCH] Set docstring of function as None if not declared

In cpython, if there is no docstring declared in function definition,
the `__doc__` attribute of the function is None.
So this implements the behavior.

Fix #1523
---
 src/compile.rs | 27 ++++++++++++++-------------
 1 file changed, 14 insertions(+), 13 deletions(-)

diff --git a/src/compile.rs b/src/compile.rs
index ca185e6..ac4f00a 100644
--- a/src/compile.rs
+++ b/src/compile.rs
@@ -1015,22 +1015,23 @@ impl<O: OutputStream> Compiler<O> {
     }
 
     fn store_docstring(&mut self, doc_str: Option<String>) {
-        if let Some(doc_string) = doc_str {
-            // Duplicate top of stack (the function or class object)
-            self.emit(Instruction::Duplicate);
+        // Duplicate top of stack (the function or class object)
+        self.emit(Instruction::Duplicate);
 
-            // Doc string value:
-            self.emit(Instruction::LoadConst {
-                value: bytecode::Constant::String {
-                    value: doc_string.to_string(),
+        // Doc string value:
+        self.emit(Instruction::LoadConst {
+            value: match doc_str {
+                Some(doc) => bytecode::Constant::String {
+                    value: doc.to_string(),
                 },
-            });
+                None => bytecode::Constant::None, // set docstring None if not declared
+            },
+        });
 
-            self.emit(Instruction::Rotate { amount: 2 });
-            self.emit(Instruction::StoreAttr {
-                name: "__doc__".to_string(),
-            });
-        }
+        self.emit(Instruction::Rotate { amount: 2 });
+        self.emit(Instruction::StoreAttr {
+            name: "__doc__".to_string(),
+        });
     }
 
     fn compile_while(