Make error_code formatter debug-enabled

Author: vitaut

include/fmt/std.h

@@ -513,6 +513,8 @@ template <> struct formatter<std::error_code> {
   bool debug_ = false;
 
  public:
+  FMT_CONSTEXPR void set_debug_format(bool set = true) { debug_ = set; }
+  
   FMT_CONSTEXPR auto parse(parse_context<>& ctx) -> const char* {
     auto it = ctx.begin(), end = ctx.end();
     if (it == end) return it;

test/std-test.cc

@@ -13,6 +13,7 @@
 #include <vector>
 
 #include "fmt/os.h"       // fmt::system_category
+#include "fmt/ranges.h"
 #include "gtest-extra.h"  // StartsWith
 
 #ifdef __cpp_lib_filesystem
@@ -335,6 +336,10 @@ TEST(std_test, error_code) {
   EXPECT_EQ(fmt::format("{:s}", ec), ec.message());
   EXPECT_EQ(fmt::format("{:?}", std::error_code(42, generic)),
             "\"generic:42\"");
+  EXPECT_EQ(fmt::format("{}",
+                        std::map<std::error_code, int>{
+                            {std::error_code(42, generic), 0}}),
+            "{\"generic:42\": 0}");
 }
 
 template <typename Catch> void exception_test() {