From 78c67157c1c74b366f92287b84969b2817955962 Mon Sep 17 00:00:00 2001
From: Alexey Ochapov <alexez@alexez.com>
Date: Tue, 16 Feb 2021 07:04:52 +0300
Subject: [PATCH] prepare tests, fix incorrect handling of named args with
 simple `{}` replacement fields

---
 include/fmt/compile.h | 22 +++++++++++++++++-----
 test/compile-test.cc  | 39 ++++++++++++++++++++++++++++-----------
 2 files changed, 45 insertions(+), 16 deletions(-)

diff --git a/include/fmt/compile.h b/include/fmt/compile.h
index 2f613db0..30ee85df 100644
--- a/include/fmt/compile.h
+++ b/include/fmt/compile.h
@@ -454,9 +454,14 @@ template <typename Char, typename T, int N> struct field {
 
   template <typename OutputIt, typename... Args>
   constexpr OutputIt format(OutputIt out, const Args&... args) const {
-    // This ensures that the argument type is convertile to `const T&`.
-    const T& arg = get<N>(args...);
-    return write<Char>(out, arg);
+    if constexpr (is_named_arg<typename std::remove_cv<T>::type>::value) {
+      decltype(T::value) arg = get<N>(args...).value;
+      return write<Char>(out, arg);
+    } else {
+      // This ensures that the argument type is convertile to `const T&`.
+      const T& arg = get<N>(args...);
+      return write<Char>(out, arg);
+    }
   }
 };
 
@@ -775,8 +780,15 @@ FMT_INLINE std::basic_string<typename S::char_type> format(const S&,
 #ifdef __cpp_if_constexpr
   if constexpr (std::is_same<typename S::char_type, char>::value) {
     constexpr basic_string_view<typename S::char_type> str = S();
-    if constexpr (str.size() == 2 && str[0] == '{' && str[1] == '}')
-      return fmt::to_string(detail::first(args...));
+    if constexpr (str.size() == 2 && str[0] == '{' && str[1] == '}') {
+      auto first = detail::first(args...);
+      if constexpr (detail::is_named_arg<typename std::remove_cv<
+                        decltype(first)>::type>::value) {
+        return fmt::to_string(first.value);
+      } else {
+        return fmt::to_string(first);
+      }
+    }
   }
 #endif
   constexpr auto compiled = detail::compile<Args...>(S());
diff --git a/test/compile-test.cc b/test/compile-test.cc
index cab2e8b4..ce23c2f5 100644
--- a/test/compile-test.cc
+++ b/test/compile-test.cc
@@ -255,17 +255,34 @@ TEST(CompileTest, ManualOrdering) {
 }
 
 TEST(CompileTest, Named) {
-  EXPECT_EQ("41 43", fmt::format(FMT_COMPILE("{name1} {name2}"),
-                                 fmt::arg("name1", 41), fmt::arg("name2", 43)));
-  EXPECT_EQ("41 43",
-            fmt::format(FMT_COMPILE("{} {name2}"), 41, fmt::arg("name2", 43)));
-  EXPECT_EQ("41 43",
-            fmt::format(FMT_COMPILE("{name1} {}"), fmt::arg("name1", 41), 43));
-  EXPECT_EQ("41 43",
-            fmt::format(FMT_COMPILE("{name1} {name2}"), fmt::arg("name1", 41),
-                        fmt::arg("name2", 43), fmt::arg("name3", 42)));
-  EXPECT_EQ("41 43", fmt::format(FMT_COMPILE("{name2} {name1}"),
-                                 fmt::arg("name1", 43), fmt::arg("name2", 41)));
+  EXPECT_EQ("42", fmt::format(FMT_COMPILE("{}"), fmt::arg("arg", 42)));
+  EXPECT_EQ("41 43", fmt::format(FMT_COMPILE("{} {}"), fmt::arg("arg", 41),
+                                 fmt::arg("arg", 43)));
+
+  EXPECT_EQ("foobar",
+            fmt::format(FMT_COMPILE("{a0}{a1}"), fmt::arg("a0", "foo"),
+                        fmt::arg("a1", "bar")));
+  EXPECT_EQ("foobar",
+            fmt::format(/*FMT_COMPILE(*/ "{}{a1}" /*)*/, fmt::arg("a0", "foo"),
+                        fmt::arg("a1", "bar")));
+  EXPECT_EQ("foofoo",
+            fmt::format(/*FMT_COMPILE(*/ "{a0}{}" /*)*/, fmt::arg("a0", "foo"),
+                        fmt::arg("a1", "bar")));
+  EXPECT_EQ("foobar",
+            fmt::format(/*FMT_COMPILE(*/ "{a0}{1}" /*)*/, fmt::arg("a0", "foo"),
+                        fmt::arg("a1", "bar")));
+  EXPECT_EQ("foobar",
+            fmt::format(/*FMT_COMPILE(*/ "{0}{a1}" /*)*/, fmt::arg("a0", "foo"),
+                        fmt::arg("a1", "bar")));
+
+  EXPECT_EQ("foobar",
+            fmt::format(FMT_COMPILE("{}{a1}"), "foo", fmt::arg("a1", "bar")));
+  EXPECT_EQ("foobar",
+            fmt::format(FMT_COMPILE("{a0}{a1}"), fmt::arg("a1", "bar"),
+                        fmt::arg("a2", "baz"), fmt::arg("a0", "foo")));
+  EXPECT_EQ(" bar foo ",
+            fmt::format(FMT_COMPILE(" {foo} {bar} "), fmt::arg("foo", "bar"),
+                        fmt::arg("bar", "foo")));
 
   EXPECT_THROW(fmt::format(FMT_COMPILE("{invalid}"), fmt::arg("valid", 42)),
                fmt::format_error);