Implement pad for wide strings.

format.h

@@ -504,9 +504,15 @@ DEFINE_INT_FORMATTERS(unsigned long long)
 
   \endrst
  */
-inline StrFormatSpec<char> pad(
-    const char *str, unsigned width, wchar_t fill = ' ') {
-  return StrFormatSpec<char>(str, AlignSpec(width, fill));
+template <typename Char>
+inline StrFormatSpec<Char> pad(
+    const Char *str, unsigned width, Char fill = ' ') {
+  return StrFormatSpec<Char>(str, AlignSpec(width, fill));
+}
+
+inline StrFormatSpec<wchar_t> pad(
+    const wchar_t *str, unsigned width, char fill = ' ') {
+  return StrFormatSpec<wchar_t>(str, AlignSpec(width, fill));
 }
 
 template <typename Char>
@@ -712,10 +718,10 @@ class BasicWriter {
   template <typename T, typename Spec>
   BasicWriter &operator<<(const IntFormatSpec<T, Spec> &spec);
 
-  template <typename T>
-  BasicWriter &operator<<(const StrFormatSpec<T> &spec) {
-    const char *s = spec.str();
-    FormatString(s, std::strlen(s), spec);
+  template <typename StringChar>
+  BasicWriter &operator<<(const StrFormatSpec<StringChar> &spec) {
+    const StringChar *s = spec.str();
+    FormatString(s, std::char_traits<Char>::length(s), spec);
     return *this;
   }
 

format_test.cc

@@ -56,6 +56,7 @@ using fmt::Format;
 using fmt::FormatError;
 using fmt::StringRef;
 using fmt::Writer;
+using fmt::WWriter;
 using fmt::pad;
 
 #define FORMAT_TEST_THROW_(statement, expected_exception, message, fail) \
@@ -447,6 +448,12 @@ TEST(WriterTest, PadString) {
   EXPECT_EQ("test******", str(Writer() << pad("test", 10, '*')));
 }
 
+TEST(WriterTest, PadWString) {
+  EXPECT_EQ(L"test    ", str(WWriter() << pad(L"test", 8)));
+  EXPECT_EQ(L"test******", str(WWriter() << pad(L"test", 10, '*')));
+  EXPECT_EQ(L"test******", str(WWriter() << pad(L"test", 10, L'*')));
+}
+
 TEST(WriterTest, NoConflictWithIOManip) {
   using namespace std;
   using namespace fmt;