Allow formatting C strings as pointers (#223)

test/format-test.cc

@@ -1336,7 +1336,7 @@ TEST(FormatterTest, FormatWChar) {
 }
 
 TEST(FormatterTest, FormatCString) {
-  check_unknown_types("test", "s", "string");
+  check_unknown_types("test", "sp", "string");
   EXPECT_EQ("test", format("{0}", "test"));
   EXPECT_EQ("test", format("{0:s}", "test"));
   char nonconst[] = "nonconst";

test/printf-test.cc

@@ -425,6 +425,8 @@ TEST(PrintfTest, Pointer) {
   int n;
   void *p = &n;
   EXPECT_PRINTF(fmt::format("{}", p), "%p", p);
+  const char *s = "test";
+  EXPECT_PRINTF(fmt::format("{:p}", s), "%p", s);
 }
 
 TEST(PrintfTest, Custom) {

test/util-test.cc

@@ -593,6 +593,7 @@ struct TestVisitor : fmt::internal::ArgVisitor<TestVisitor, Result> {
   Result visit_double(double value) { return value; }
   Result visit_long_double(long double value) { return value; }
   Result visit_char(int value) { return static_cast<char>(value); }
+  Result visit_cstring(const char *s) { return s; }
   Result visit_string(Arg::StringValue<char> s) { return s.value; }
   Result visit_wstring(Arg::StringValue<wchar_t> s) { return s.value; }
   Result visit_pointer(const void *p) { return p; }