From c1557a72ac282b04596f9d82706123881ae49f5d Mon Sep 17 00:00:00 2001
From: mutouyun <orz@orzz.org>
Date: Sun, 15 May 2022 19:58:53 +0800
Subject: [PATCH] fix: [vs2015] error C3250: 'u': declaration is not allowed in
 'constexpr' function body

---
 include/libimp/horrible_cast.h | 16 +++++++++++-----
 include/libimp/result.h        |  2 +-
 src/libimp/CMakeLists.txt      |  5 +++++
 src/libipc/CMakeLists.txt      |  5 +++++
 4 files changed, 22 insertions(+), 6 deletions(-)

diff --git a/include/libimp/horrible_cast.h b/include/libimp/horrible_cast.h
index 88520c6..cce6ef7 100644
--- a/include/libimp/horrible_cast.h
+++ b/include/libimp/horrible_cast.h
@@ -12,14 +12,20 @@
 
 LIBIMP_NAMESPACE_BEG_
 
+namespace detail_horrible_cast {
+
+template <typename T, typename U>
+union temp {
+  std::decay_t<U> in;
+  T out;
+};
+
+} // namespace detail_horrible_cast
+
 template <typename T, typename U>
 constexpr auto horrible_cast(U &&in) noexcept
   -> std::enable_if_t<(sizeof(T) == sizeof(std::decay_t<U>)), T> {
-  union {
-    std::decay_t<U> in;
-    T out;
-  } u {std::forward<U>(in)};
-  return u.out;
+  return detail_horrible_cast::temp<T, std::decay_t<U>>{std::forward<U>(in)}.out;
 }
 
 LIBIMP_NAMESPACE_END_
diff --git a/include/libimp/result.h b/include/libimp/result.h
index e72052b..81f94c8 100644
--- a/include/libimp/result.h
+++ b/include/libimp/result.h
@@ -154,7 +154,7 @@ LIBIMP_NAMESPACE_END_
 
 template <typename T, typename D>
 struct fmt::formatter<::LIBIMP_::result<T, D>> {
-  constexpr auto parse(format_parse_context& ctx) {
+  constexpr auto parse(format_parse_context& ctx) const {
     return ctx.end();
   }
 
diff --git a/src/libimp/CMakeLists.txt b/src/libimp/CMakeLists.txt
index 65e3405..4e5fc42 100644
--- a/src/libimp/CMakeLists.txt
+++ b/src/libimp/CMakeLists.txt
@@ -1,5 +1,10 @@
 project(imp)
 
+if(NOT MSVC)
+  add_compile_options(
+    -Wno-attributes)
+endif()
+
 aux_source_directory(${LIBIPC_PROJECT_DIR}/src/libimp SRC_FILES)
 
 file(GLOB HEAD_FILES
diff --git a/src/libipc/CMakeLists.txt b/src/libipc/CMakeLists.txt
index 60007c1..7eed20b 100644
--- a/src/libipc/CMakeLists.txt
+++ b/src/libipc/CMakeLists.txt
@@ -1,5 +1,10 @@
 project(ipc)
 
+if(NOT MSVC)
+  add_compile_options(
+    -Wno-attributes)
+endif()
+
 aux_source_directory(${LIBIPC_PROJECT_DIR}/src/libipc SRC_FILES)
 
 file(GLOB HEAD_FILES