From: jacobly0 <jacobly0@users.noreply.github.com>
Date: Sun, 8 May 2022 14:12:28 +0000 (+0200)
Subject: fix: Fix miscompile of nonstd::expected on MSVC v19.22 (#1053)
X-Git-Tag: v4.6.1~19
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e97a52820f34c4be8e628eea76885b1ded71518b;p=thirdparty%2Fccache.git

fix: Fix miscompile of nonstd::expected on MSVC v19.22 (#1053)
---

diff --git a/src/third_party/nonstd/expected.hpp b/src/third_party/nonstd/expected.hpp
index 69bee7506..2bd18344a 100644
--- a/src/third_party/nonstd/expected.hpp
+++ b/src/third_party/nonstd/expected.hpp
@@ -1,6 +1,6 @@
 // This version targets C++11 and later.
 //
-// Copyright (C) 2016-2018 Martin Moene.
+// Copyright (C) 2016-2020 Martin Moene.
 //
 // Distributed under the Boost Software License, Version 1.0.
 // (See accompanying file LICENSE.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
@@ -66,16 +66,25 @@
 # define nsel_P0323R  7
 #endif
 
-// Control presence of exception handling (try and auto discover):
+// Control presence of C++ exception handling (try and auto discover):
 
 #ifndef nsel_CONFIG_NO_EXCEPTIONS
-# if defined(__cpp_exceptions) || defined(__EXCEPTIONS) || defined(_CPPUNWIND)
+# if defined(_MSC_VER)
+#  include <cstddef>    // for _HAS_EXCEPTIONS
+# endif
+# if defined(__cpp_exceptions) || defined(__EXCEPTIONS) || (_HAS_EXCEPTIONS)
 #  define nsel_CONFIG_NO_EXCEPTIONS  0
 # else
 #  define nsel_CONFIG_NO_EXCEPTIONS  1
 # endif
 #endif
 
+// at default use SEH with MSVC for no C++ exceptions
+
+#ifndef  nsel_CONFIG_NO_EXCEPTIONS_SEH
+# define nsel_CONFIG_NO_EXCEPTIONS_SEH  ( nsel_CONFIG_NO_EXCEPTIONS && _MSC_VER )
+#endif
+
 // C++ language version detection (C++20 is speculative):
 // Note: VC14.0/1900 (VS2015) lacks too much from C++14.
 
@@ -224,7 +233,11 @@ namespace nonstd {
 // additional includes:
 
 #if nsel_CONFIG_NO_EXCEPTIONS
+# if nsel_CONFIG_NO_EXCEPTIONS_SEH
+#  include <windows.h>   // for ExceptionCodes
+# else
 // already included: <cassert>
+# endif
 #else
 # include <stdexcept>
 #endif
@@ -1260,7 +1273,11 @@ struct error_traits
 {
     static void rethrow( Error const & /*e*/ )
     {
+#if nsel_CONFIG_NO_EXCEPTIONS_SEH
+        RaiseException( EXCEPTION_ACCESS_VIOLATION, EXCEPTION_NONCONTINUABLE, 0, NULL );
+#else
         assert( false && detail::text("throw bad_expected_access<Error>{ e };") );
+#endif
     }
 };
 
@@ -1269,7 +1286,11 @@ struct error_traits< std::exception_ptr >
 {
     static void rethrow( std::exception_ptr const & /*e*/ )
     {
+#if nsel_CONFIG_NO_EXCEPTIONS_SEH
+        RaiseException( EXCEPTION_ACCESS_VIOLATION, EXCEPTION_NONCONTINUABLE, 0, NULL );
+#else
         assert( false && detail::text("throw bad_expected_access<std::exception_ptr>{ e };") );
+#endif
     }
 };
 
@@ -1278,7 +1299,11 @@ struct error_traits< std::error_code >
 {
     static void rethrow( std::error_code const & /*e*/ )
     {
+#if nsel_CONFIG_NO_EXCEPTIONS_SEH
+        RaiseException( EXCEPTION_ACCESS_VIOLATION, EXCEPTION_NONCONTINUABLE, 0, NULL );
+#else
         assert( false && detail::text("throw std::system_error( e );") );
+#endif
     }
 };
 
@@ -1639,10 +1664,11 @@ public:
         return *this;
     }
 
-    template< typename G
+    template< typename G = E
         nsel_REQUIRES_T(
-            std::is_copy_constructible<E>::value    // TODO: std::is_nothrow_copy_constructible<E>
-            && std::is_copy_assignable<E>::value
+            std::is_constructible<E, G const&>::value &&
+            std::is_copy_constructible<G>::value    // TODO: std::is_nothrow_copy_constructible<G>
+            && std::is_copy_assignable<G>::value
         )
     >
     expected & operator=( nonstd::unexpected_type<G> const & error )
@@ -1651,10 +1677,11 @@ public:
         return *this;
     }
 
-    template< typename G
+    template< typename G = E
         nsel_REQUIRES_T(
-            std::is_move_constructible<E>::value    // TODO: std::is_nothrow_move_constructible<E>
-            && std::is_move_assignable<E>::value
+            std::is_constructible<E, G&&>::value &&
+            std::is_move_constructible<G>::value    // TODO: std::is_nothrow_move_constructible<G>
+            && std::is_move_assignable<G>::value
         )
     >
     expected & operator=( nonstd::unexpected_type<G> && error )
@@ -1742,12 +1769,12 @@ public:
 
     constexpr value_type const && operator *() const &&
     {
-        return assert( has_value() ), std::move( contained.value() );
+        return std::move( ( assert( has_value() ), contained.value() ) );
     }
 
     nsel_constexpr14 value_type && operator *() &&
     {
-        return assert( has_value() ), std::move( contained.value() );
+        return std::move( ( assert( has_value() ), contained.value() ) );
     }
 
 #endif
@@ -1808,12 +1835,12 @@ public:
 
     constexpr error_type const && error() const &&
     {
-        return assert( ! has_value() ), std::move( contained.error() );
+        return std::move( ( assert( ! has_value() ), contained.error() ) );
     }
 
     error_type && error() &&
     {
-        return assert( ! has_value() ), std::move( contained.error() );
+        return std::move( ( assert( ! has_value() ), contained.error() ) );
     }
 
 #endif
@@ -2080,12 +2107,12 @@ public:
 
     constexpr error_type const && error() const &&
     {
-        return assert( ! has_value() ), std::move( contained.error() );
+        return std::move( ( assert( ! has_value() ), contained.error() ) );
     }
 
     error_type && error() &&
     {
-        return assert( ! has_value() ), std::move( contained.error() );
+        return std::move( ( assert( ! has_value() ), contained.error() ) );
     }
 
 #endif