From 1741e90dec69ba8004530e837b35caa1e75af690 Mon Sep 17 00:00:00 2001
From: Victor Zverovich <viz@fb.com>
Date: Sat, 18 Feb 2023 09:39:58 -0800
Subject: [PATCH] Always call parse in range formatter

---
 include/fmt/ranges.h | 24 ++++++++++++------------
 test/ranges-test.cc  | 17 ++++++++++-------
 2 files changed, 22 insertions(+), 19 deletions(-)

diff --git a/include/fmt/ranges.h b/include/fmt/ranges.h
index 8912fe93..755f49df 100644
--- a/include/fmt/ranges.h
+++ b/include/fmt/ranges.h
@@ -235,7 +235,7 @@ void for_each(index_sequence<Is...>, Tuple&& tup, F&& f) noexcept {
 }
 
 template <class T>
-FMT_CONSTEXPR auto get_indexes(T const&)
+FMT_CONSTEXPR auto get_indexes(const T&)
     -> make_index_sequence<std::tuple_size<T>::value> {
   return {};
 }
@@ -361,7 +361,7 @@ struct formatter<Tuple, Char,
     return ctx.begin();
   }
 
-  template <typename FormatContext = format_context>
+  template <typename FormatContext>
   auto format(const Tuple& value, FormatContext& ctx) const
       -> decltype(ctx.out()) {
     auto out = detail::copy_str<Char>(opening_bracket_, ctx.out());
@@ -437,13 +437,13 @@ struct range_formatter<
   basic_string_view<Char> closing_bracket_ =
       detail::string_literal<Char, ']'>{};
 
-  template <class U>
+  template <typename U>
   FMT_CONSTEXPR static auto maybe_set_debug_format(U& u, bool set)
       -> decltype(u.set_debug_format(set)) {
     u.set_debug_format(set);
   }
 
-  template <class U>
+  template <typename U>
   FMT_CONSTEXPR static void maybe_set_debug_format(U&, ...) {}
 
   FMT_CONSTEXPR void maybe_set_debug_format(bool set) {
@@ -451,7 +451,7 @@ struct range_formatter<
   }
 
  public:
-  FMT_CONSTEXPR range_formatter() { maybe_set_debug_format(true); }
+  FMT_CONSTEXPR range_formatter() {}
 
   FMT_CONSTEXPR auto underlying() -> detail::range_formatter_type<Char, T>& {
     return underlying_;
@@ -477,14 +477,14 @@ struct range_formatter<
       ++it;
     }
 
-    if (it == end || *it == '}') return it;
+    if (it != end && *it != '}') {
+      if (*it != ':') FMT_THROW(format_error("invalid format specifier"));
+      custom_specs_ = true;
+      ++it;
+    } else {
+      maybe_set_debug_format(true);
+    }
 
-    if (*it != ':')
-      FMT_THROW(format_error("no other top-level range formatters supported"));
-
-    maybe_set_debug_format(false);
-    custom_specs_ = true;
-    ++it;
     ctx.advance_to(it);
     return underlying_.parse(ctx);
   }
diff --git a/test/ranges-test.cc b/test/ranges-test.cc
index 26e3362a..29ec401a 100644
--- a/test/ranges-test.cc
+++ b/test/ranges-test.cc
@@ -366,7 +366,7 @@ TEST(ranges_test, is_printable) {
   EXPECT_FALSE(is_printable(0x110000));
 }
 
-TEST(ranges_test, escape_string) {
+TEST(ranges_test, escape) {
   using vec = std::vector<std::string>;
   EXPECT_EQ(fmt::format("{}", vec{"\n\r\t\"\\"}), "[\"\\n\\r\\t\\\"\\\\\"]");
   EXPECT_EQ(fmt::format("{}", vec{"\x07"}), "[\"\\x07\"]");
@@ -386,8 +386,11 @@ TEST(ranges_test, escape_string) {
               "[\"\\xf0(\\x00\\x00anything\"]");
 
     // Correct utf-8.
-    EXPECT_EQ(fmt::format("{}", vec{"понедельник"}), "[\"понедельник\"]");
+    EXPECT_EQ(fmt::format("{}", vec{"🦄"}), "[\"🦄\"]");
   }
+
+  EXPECT_EQ(fmt::format("{}", std::vector<std::vector<char>>{{'x'}}),
+            "[['x']]");
 }
 
 template <typename R> struct fmt_ref_view {
@@ -420,7 +423,7 @@ TEST(ranges_test, container_adaptor) {
   }
 
   {
-    std::stack<int> s;
+    auto s = std::stack<int>();
     s.push(1);
     s.push(2);
     EXPECT_EQ(fmt::format("{}", s), "[1, 2]");
@@ -428,14 +431,14 @@ TEST(ranges_test, container_adaptor) {
   }
 
   {
-    std::queue<int> q;
+    auto q = std::queue<int>();
     q.push(1);
     q.push(2);
     EXPECT_EQ(fmt::format("{}", q), "[1, 2]");
   }
 
   {
-    std::priority_queue<int> q;
+    auto q = std::priority_queue<int>();
     q.push(3);
     q.push(1);
     q.push(2);
@@ -444,7 +447,7 @@ TEST(ranges_test, container_adaptor) {
   }
 
   {
-    std::stack<char, std::string> s;
+    auto s = std::stack<char, std::string>();
     s.push('a');
     s.push('b');
     // See https://cplusplus.github.io/LWG/issue3881.
@@ -461,7 +464,7 @@ TEST(ranges_test, container_adaptor) {
       container_type c;
     };
 
-    my_container_adaptor m;
+    auto m = my_container_adaptor();
     m.push(1);
     m.push(2);
     EXPECT_EQ(fmt::format("{}", m), "[1, 2]");