From df03765560272c79065dce167c1124a9a3b0865e Mon Sep 17 00:00:00 2001
From: andgrew <grumandrew@gmail.com>
Date: Tue, 4 Dec 2018 08:56:57 +0300
Subject: [PATCH 1/3] add c variant for old str formatting

---
 grumpy-runtime-src/runtime/str.go | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/grumpy-runtime-src/runtime/str.go b/grumpy-runtime-src/runtime/str.go
index 9b56ed18..78809b38 100644
--- a/grumpy-runtime-src/runtime/str.go
+++ b/grumpy-runtime-src/runtime/str.go
@@ -1181,6 +1181,13 @@ func strMod(f *Frame, v, args *Object) (*Object, *BaseException) {
 				val = strLeftPad(val, fieldWidth, fillchar)
 			}
 			buf.WriteString(val)
+		case "c":
+		    if value.isInstance(IntType) {
+		        val = string(toIntUnsafe(value).Value())
+		    } else {
+		        val = toStrUnsafe(value).Value()
+		    }
+		    buf.WriteString(val)
 		case "%":
 			val = "%"
 			if fieldWidth > 0 {

From 14ae8d50524d5d5c549e08c12c4f44c547a8ac2e Mon Sep 17 00:00:00 2001
From: wind <aa.veter@gmail.com>
Date: Tue, 4 Dec 2018 23:26:47 +0300
Subject: [PATCH 2/3] fix gofmt for str.go

---
 grumpy-runtime-src/runtime/str.go | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/grumpy-runtime-src/runtime/str.go b/grumpy-runtime-src/runtime/str.go
index 78809b38..571e708d 100644
--- a/grumpy-runtime-src/runtime/str.go
+++ b/grumpy-runtime-src/runtime/str.go
@@ -1182,12 +1182,12 @@ func strMod(f *Frame, v, args *Object) (*Object, *BaseException) {
 			}
 			buf.WriteString(val)
 		case "c":
-		    if value.isInstance(IntType) {
-		        val = string(toIntUnsafe(value).Value())
-		    } else {
-		        val = toStrUnsafe(value).Value()
-		    }
-		    buf.WriteString(val)
+			if value.isInstance(IntType) {
+				val = string(toIntUnsafe(value).Value())
+			} else {
+				val = toStrUnsafe(value).Value()
+			}
+			buf.WriteString(val)
 		case "%":
 			val = "%"
 			if fieldWidth > 0 {

From b97ac546648297b8584c8c2f81ced00f2cc5748f Mon Sep 17 00:00:00 2001
From: wind <aa.veter@gmail.com>
Date: Wed, 5 Dec 2018 11:56:30 +0300
Subject: [PATCH 3/3] test for c variant

---
 grumpy-runtime-src/testing/str_test.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/grumpy-runtime-src/testing/str_test.py b/grumpy-runtime-src/testing/str_test.py
index 92e7236f..0d47b032 100644
--- a/grumpy-runtime-src/testing/str_test.py
+++ b/grumpy-runtime-src/testing/str_test.py
@@ -369,3 +369,6 @@ def __int__(self):
 assert '%o' % 8 == '10'
 assert '%o' % -8 == '-10'
 assert '%o %o' % (8, -8) == '10 -10'
+
+assert '%c' % 107 == 'k'
+assert '%c' % 'k' == 'k'