Add formatter for std::exception

Co-authored-by: fekir <[email protected]> Co-authored-by: Alexey Ochapov <[email protected]>
fmtlib · Aug 27, 2022 · f40db2f · f40db2f
1 parent a337011
commit f40db2f
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Showing 2 changed files with 35 additions and 2 deletions.
diff --git a/include/fmt/std.h b/include/fmt/std.h
@@ -8,6 +8,7 @@
 #ifndef FMT_STD_H_
 #define FMT_STD_H_
 
+#include <exception>
 #include <thread>
 #include <type_traits>
 #include <utility>
@@ -166,6 +167,22 @@ struct formatter<
   }
 };
 FMT_END_NAMESPACE
-#endif
+
+#endif  // __cpp_lib_variant
+
+FMT_BEGIN_NAMESPACE
+template <typename Char, typename T>
+struct formatter<T, Char,
+                 std::enable_if_t<std::is_base_of_v<std::exception, T>>>
+    : formatter<basic_string_view<Char>> {
+  template <typename FormatContext>
+  auto format(const std::exception& ex, FormatContext& ctx) const ->
+      typename FormatContext::iterator {
+    auto out = ctx.out();
+    detail::write(out, ex.what());
+    return out;
+  }
+};
+FMT_END_NAMESPACE
 
 #endif  // FMT_STD_H_
diff --git a/test/std-test.cc b/test/std-test.cc
@@ -6,11 +6,11 @@
 // For the license information refer to format.h.
 
 #include "fmt/std.h"
-#include "fmt/ranges.h"
 
 #include <string>
 #include <vector>
 
+#include "fmt/ranges.h"
 #include "gtest/gtest.h"
 
 TEST(std_test, path) {
@@ -77,3 +77,19 @@ TEST(std_test, variant) {
   EXPECT_EQ(fmt::format("{}", v5), "variant(\"yes, this is variant\")");
 #endif
 }
+
+TEST(std_test, exception) {
+  try {
+    std::vector<int> vec;
+    std::ignore = vec.at(42);
+  } catch (const std::exception& ex) {
+    EXPECT_EQ(fmt::format("{}", ex), "invalid vector subscript");
+  }
+
+  try {
+    std::vector<int> vec;
+    std::ignore = vec.at(42);
+  } catch (const std::out_of_range& ex) {
+    EXPECT_EQ(fmt::format("{}", ex), "invalid vector subscript");
+  }
+}