From b5fda1c90d94aeaf96081477c9bfe13789c00e03 Mon Sep 17 00:00:00 2001
From: vitaut <victor.zverovich@gmail.com>
Date: Wed, 11 Nov 2015 07:57:19 -0800
Subject: [PATCH] Format null pointer as (nil) and null string as (null) in
 printf (#226)

---
 format.cc           | 14 ++++++++++++++
 test/printf-test.cc |  4 ++++
 2 files changed, 18 insertions(+)

diff --git a/format.cc b/format.cc
index 2168ce6f..336d91b9 100644
--- a/format.cc
+++ b/format.cc
@@ -540,6 +540,20 @@ class PrintfArgFormatter :
     *out = static_cast<Char>(value);
   }
 
+  void visit_cstring(const char *value) {
+    if (value)
+      BasicArgFormatter<PrintfArgFormatter<Char>, Char>::visit_cstring(value);
+    else
+      this->writer() << "(null)";
+  }
+
+  void visit_pointer(const void *value) {
+    if (value)
+      BasicArgFormatter<PrintfArgFormatter<Char>, Char>::visit_pointer(value);
+    else
+      this->writer() << "(nil)";
+  }
+
   void visit_custom(Arg::CustomValue c) {
     BasicFormatter<Char> formatter(ArgList(), this->writer());
     const Char format_str[] = {'}', 0};
diff --git a/test/printf-test.cc b/test/printf-test.cc
index 8f8647f0..f4faaf1c 100644
--- a/test/printf-test.cc
+++ b/test/printf-test.cc
@@ -418,6 +418,8 @@ TEST(PrintfTest, Char) {
 
 TEST(PrintfTest, String) {
   EXPECT_PRINTF("abc", "%s", "abc");
+  const char *null_str = 0;
+  EXPECT_PRINTF("(null)", "%s", null_str);
   // TODO: wide string
 }
 
@@ -425,6 +427,8 @@ TEST(PrintfTest, Pointer) {
   int n;
   void *p = &n;
   EXPECT_PRINTF(fmt::format("{}", p), "%p", p);
+  p = 0;
+  EXPECT_PRINTF("(nil)", "%p", p);
   const char *s = "test";
   EXPECT_PRINTF(fmt::format("{:p}", s), "%p", s);
 }