From 21c8b5c1421ae04df00a97e4c396ffb7b26916bc Mon Sep 17 00:00:00 2001
From: Victor Zverovich <viz@fb.com>
Date: Thu, 30 Jul 2020 07:16:15 -0700
Subject: [PATCH] Report error on missing named argument (#1796)

---
 include/fmt/core.h  | 2 +-
 test/format-test.cc | 3 ++-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/include/fmt/core.h b/include/fmt/core.h
index 4f662964..a9d07de5 100644
--- a/include/fmt/core.h
+++ b/include/fmt/core.h
@@ -1913,7 +1913,7 @@ template <typename Context> class basic_format_args {
   }
 
   template <typename Char> int get_id(basic_string_view<Char> name) const {
-    if (!has_named_args()) return {};
+    if (!has_named_args()) return -1;
     const auto& named_args =
         (is_packed() ? values_[-1] : args_[-1].value_).named_args;
     for (size_t i = 0; i < named_args.size; ++i) {
diff --git a/test/format-test.cc b/test/format-test.cc
index 31f8595f..6e6b6af9 100644
--- a/test/format-test.cc
+++ b/test/format-test.cc
@@ -543,7 +543,6 @@ TEST(FormatterTest, ManyArgs) {
 TEST(FormatterTest, NamedArg) {
   EXPECT_EQ("1/a/A", format("{_1}/{a_}/{A_}", fmt::arg("a_", 'a'),
                             fmt::arg("A_", "A"), fmt::arg("_1", 1)));
-  EXPECT_THROW_MSG(format("{a}"), format_error, "argument not found");
   EXPECT_EQ(" -42", format("{0:{width}}", -42, fmt::arg("width", 4)));
   EXPECT_EQ("st", format("{0:.{precision}}", "str", fmt::arg("precision", 2)));
   EXPECT_EQ("1 2", format("{} {two}", 1, fmt::arg("two", 2)));
@@ -553,6 +552,8 @@ TEST(FormatterTest, NamedArg) {
                          fmt::arg("i", 0), fmt::arg("j", 0), fmt::arg("k", 0),
                          fmt::arg("l", 0), fmt::arg("m", 0), fmt::arg("n", 0),
                          fmt::arg("o", 0), fmt::arg("p", 0)));
+  EXPECT_THROW_MSG(format("{a}"), format_error, "argument not found");
+  EXPECT_THROW_MSG(format("{a}", 42), format_error, "argument not found");
 }
 
 TEST(FormatterTest, AutoArgIndex) {