Improve error reporting (#357)

test/format-test.cc

@@ -1366,7 +1366,7 @@ TEST(FormatterTest, FormatCStringRef) {
   EXPECT_EQ("test", format("{0}", CStringRef("test")));
 }
 
-void format(fmt::BasicFormatter<char> &f, const char *, const Date &d) {
+void format_arg(fmt::BasicFormatter<char> &f, const char *, const Date &d) {
   f.writer() << d.year() << '-' << d.month() << '-' << d.day();
 }
 
@@ -1379,7 +1379,7 @@ TEST(FormatterTest, FormatCustom) {
 class Answer {};
 
 template <typename Char>
-void format(fmt::BasicFormatter<Char> &f, const Char *, Answer) {
+void format_arg(fmt::BasicFormatter<Char> &f, const Char *, Answer) {
   f.writer() << "42";
 }
 

test/util-test.cc

@@ -64,7 +64,7 @@ namespace {
 struct Test {};
 
 template <typename Char>
-void format(fmt::BasicFormatter<Char> &f, const Char *, Test) {
+void format_arg(fmt::BasicFormatter<Char> &f, const Char *, Test) {
   f.writer() << "test";
 }
 
@@ -581,7 +581,7 @@ struct CustomFormatter {
   typedef char Char;
 };
 
-void format(CustomFormatter &, const char *&s, const Test &) {
+void format_arg(CustomFormatter &, const char *&s, const Test &) {
   s = "custom_format";
 }