Handle Clang on Windows in pretty_name

Summary: [Folly] Handle Clang on Windows in `pretty_name`.

Reviewed By: Orvid

Differential Revision: D14844690

fbshipit-source-id: 1f995604d5be0cd571caa344e5b18f877188390d

folly/lang/Pretty.h

@@ -17,6 +17,7 @@
 #pragma once
 
 #include <cstddef>
+#include <type_traits>
 
 #include <folly/Portability.h>
 
@@ -72,41 +73,54 @@ static constexpr std::size_t pretty_rfind(
   return ~std::size_t(0);
 }
 
+struct pretty_tag_msc {};
+struct pretty_tag_gcc {};
+
+using pretty_default_tag = std::conditional_t< //
+    kMscVer && !kIsClang,
+    pretty_tag_msc,
+    pretty_tag_gcc>;
+
 template <typename T>
-static constexpr auto pretty_raw() {
+static constexpr auto pretty_raw(pretty_tag_msc) {
 #if _MSC_VER
   return pretty_carray_from(__FUNCSIG__);
-#else
+#endif
+}
+
+template <typename T>
+static constexpr auto pretty_raw(pretty_tag_gcc) {
+#if __GNUC__ || __clang__
   return pretty_carray_from(__PRETTY_FUNCTION__);
 #endif
 }
 
 template <std::size_t S>
-static constexpr pretty_info pretty_parse_msc(char const (&name)[S]) {
-  //  void __cdecl folly::detail::pretty_raw<{...}>(void)
+static constexpr pretty_info pretty_parse(
+    pretty_tag_msc,
+    char const (&name)[S]) {
+  //  void __cdecl folly::detail::pretty_raw<{...}>(
+  //      folly::detail::pretty_tag_msc)
   auto const la = pretty_lfind(name, '<');
   auto const rp = pretty_rfind(name, '>');
   return pretty_info{la + 1, rp};
 }
 
 template <std::size_t S>
-static constexpr pretty_info pretty_parse_gcc(char const (&name)[S]) {
-  //  void folly::detail::pretty_raw() [T = {...}]
+static constexpr pretty_info pretty_parse(
+    pretty_tag_gcc,
+    char const (&name)[S]) {
+  //  void folly::detail::pretty_raw(
+  //      folly::detail::pretty_tag_gcc) [T = {...}]
   auto const eq = pretty_lfind(name, '=');
   auto const br = pretty_rfind(name, ']');
   return pretty_info{eq + 2, br};
 }
 
-template <std::size_t S>
-static constexpr pretty_info pretty_parse(char const (&name)[S]) {
-  return kMscVer ? detail::pretty_parse_msc(name)
-                 : detail::pretty_parse_gcc(name);
-}
-
-template <typename T>
+template <typename T, typename Tag>
 struct pretty_name_zarray {
-  static constexpr auto raw = pretty_raw<T>();
-  static constexpr auto info = pretty_parse(raw.data);
+  static constexpr auto raw = pretty_raw<T>(Tag{});
+  static constexpr auto info = pretty_parse(Tag{}, raw.data);
   static constexpr auto size = info.e - info.b;
   static constexpr auto zarray_() {
     pretty_carray<size + 1> data{};
@@ -119,9 +133,9 @@ struct pretty_name_zarray {
   static constexpr pretty_carray<size + 1> zarray = zarray_();
 };
 
-template <typename T>
-constexpr pretty_carray<pretty_name_zarray<T>::size + 1>
-    pretty_name_zarray<T>::zarray;
+template <typename T, typename Tag>
+constexpr pretty_carray<pretty_name_zarray<T, Tag>::size + 1>
+    pretty_name_zarray<T, Tag>::zarray;
 
 } // namespace detail
 
@@ -135,7 +149,7 @@ constexpr pretty_carray<pretty_name_zarray<T>::size + 1>
 //  present in the type name as it would be symbolized.
 template <typename T>
 constexpr char const* pretty_name() {
-  return detail::pretty_name_zarray<T>::zarray.data;
+  return detail::pretty_name_zarray<T, detail::pretty_default_tag>::zarray.data;
 }
 
 } // namespace folly

folly/lang/test/PrettyTest.cpp

@@ -28,14 +28,16 @@ TEST_F(PrettyTest, example) {
 }
 
 TEST_F(PrettyTest, example_msc) {
+  constexpr auto const tag = detail::pretty_tag_msc{};
   constexpr auto const& name = "void __cdecl foo<int>(void)";
-  constexpr auto const info = detail::pretty_parse_msc(name);
+  constexpr auto const info = detail::pretty_parse(tag, name);
   EXPECT_EQ("int", detail::pretty_info_to<std::string>(info, name));
 }
 
 TEST_F(PrettyTest, example_gcc) {
+  constexpr auto const tag = detail::pretty_tag_gcc{};
   constexpr auto const& name = "void foo() [T = int]";
-  constexpr auto const info = detail::pretty_parse_gcc(name);
+  constexpr auto const info = detail::pretty_parse(tag, name);
   EXPECT_EQ("int", detail::pretty_info_to<std::string>(info, name));
 }