<expected> Implement P0323R12 (#2643)

Co-authored-by: Stephan T. Lavavej <stl@microsoft.com>
Co-authored-by: Casey Carter <Casey@Carter.net>

stl/CMakeLists.txt

@@ -131,6 +131,7 @@ set(HEADERS
     ${CMAKE_CURRENT_LIST_DIR}/inc/deque
     ${CMAKE_CURRENT_LIST_DIR}/inc/exception
     ${CMAKE_CURRENT_LIST_DIR}/inc/execution
+    ${CMAKE_CURRENT_LIST_DIR}/inc/expected
     ${CMAKE_CURRENT_LIST_DIR}/inc/experimental/coroutine
     ${CMAKE_CURRENT_LIST_DIR}/inc/experimental/deque
     ${CMAKE_CURRENT_LIST_DIR}/inc/experimental/filesystem

stl/debugger/STL.natvis

@@ -247,6 +247,45 @@ SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   </Type>
 
 
+  <Type Name="std::unexpected&lt;*&gt;">
+      <Intrinsic Name="unex" Expression="_Unexpected"/>
+      <DisplayString>{unex()}</DisplayString>
+      <Expand>
+          <Item Name="unex">unex()</Item>
+      </Expand>
+  </Type>
+
+  <Type Name="std::bad_expected_access&lt;*&gt;">
+      <Intrinsic Name="unex" Expression="_Unexpected"/>
+      <DisplayString>{unex()}</DisplayString>
+      <Expand>
+          <Item Name="unex">unex()</Item>
+      </Expand>
+  </Type>
+
+  <Type Name="std::expected&lt;*,*&gt;">
+      <Intrinsic Name="has_value" Expression="_Has_value"/>
+      <Intrinsic Name="value" Expression="_Value"/>
+      <Intrinsic Name="unex" Expression="_Unexpected"/>
+      <DisplayString Condition="has_value()">{value()}</DisplayString>
+      <DisplayString Condition="!has_value()">{unex()}</DisplayString>
+      <Expand>
+          <Item Condition="has_value()" Name="value">value()</Item>
+          <Item Condition="!has_value()" Name="unex">unex()</Item>
+      </Expand>
+  </Type>
+
+  <Type Name="std::expected&lt;void,*&gt;">
+      <Intrinsic Name="has_value" Expression="_Has_value"/>
+      <Intrinsic Name="unex" Expression="_Unexpected"/>
+      <DisplayString Condition="has_value()">void</DisplayString>
+      <DisplayString Condition="!has_value()">{unex()}</DisplayString>
+      <Expand>
+          <Item Condition="!has_value()" Name="unex">unex()</Item>
+      </Expand>
+  </Type>
+
+
   <Type Name="std::bitset&lt;*&gt;">
       <DisplayString>{{ size={$T1} }}</DisplayString>
       <Expand>

stl/inc/__msvc_all_public_headers.hpp

@@ -88,6 +88,7 @@
 #include <complex>
 #include <deque>
 #include <exception>
+#include <expected>
 #include <filesystem>
 #include <format>
 #include <forward_list>

stl/inc/header-units.json

@@ -55,6 +55,7 @@
         "deque",
         "exception",
         "execution",
+        "expected",
         "filesystem",
         "format",
         "forward_list",

stl/inc/yvals_core.h

@@ -281,6 +281,7 @@
 
 // _HAS_CXX23 directly controls:
 // P0288R9 move_only_function
+// P0323R12 <expected>
 // P0401R6 Providing Size Feedback In The Allocator Interface
 // P0448R4 <spanstream>
 // P0627R6 unreachable()
@@ -307,6 +308,7 @@
 //     (changes to pair, tuple, and vector<bool>::reference only)
 // P2442R1 Windowing Range Adaptors: views::chunk, views::slide
 // P2443R1 views::chunk_by
+// P2549R0 unexpected<E>::error()
 
 // Parallel Algorithms Notes
 // C++ allows an implementation to implement parallel algorithms as calls to the serial algorithms.
@@ -1438,9 +1440,14 @@
 
 #define __cpp_lib_associative_heterogeneous_erasure 202110L
 #define __cpp_lib_byteswap                          202110L
-#define __cpp_lib_invoke_r                          202106L
-#define __cpp_lib_is_scoped_enum                    202011L
-#define __cpp_lib_move_only_function                202110L
+
+#ifdef __cpp_lib_concepts
+#define __cpp_lib_expected 202202L
+#endif // __cpp_lib_concepts
+
+#define __cpp_lib_invoke_r           202106L
+#define __cpp_lib_is_scoped_enum     202011L
+#define __cpp_lib_move_only_function 202110L
 
 #ifdef __cpp_lib_concepts
 #define __cpp_lib_out_ptr                 202106L

tests/std/test.lst

@@ -257,6 +257,7 @@ tests\P0220R1_searchers
 tests\P0220R1_string_view
 tests\P0288R9_move_only_function
 tests\P0295R0_gcd_lcm
+tests\P0323R12_expected
 tests\P0325R4_to_array
 tests\P0339R6_polymorphic_allocator
 tests\P0355R7_calendars_and_time_zones_clocks

tests/std/tests/P0323R12_expected/env.lst

@@ -0,0 +1,4 @@
+# Copyright (c) Microsoft Corporation.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+RUNALL_INCLUDE ..\strict_concepts_latest_matrix.lst

tests/std/tests/P1502R1_standard_library_header_units/importable_cxx_library_headers.jsonc

@@ -21,6 +21,7 @@
     "deque",
     "exception",
     "execution",
+    "expected",
     "filesystem",
     "format",
     "forward_list",

tests/std/tests/P1502R1_standard_library_header_units/test.cpp

@@ -28,6 +28,9 @@ import <coroutine>;
 import <deque>;
 import <exception>;
 import <execution>;
+#ifdef _MSVC_INTERNAL_TESTING // TRANSITION, VSO-1543660 fixed in 17.3 Preview 3
+import <expected>;
+#endif // ^^^ no workaround ^^^
 import <filesystem>;
 import <format>;
 import <forward_list>;
@@ -258,8 +261,8 @@ int main() {
         odd.join();
         even.join();
 
-        const vector<int> expected = {5, 51, 512, 5121, 51212, 512121, 5121212};
-        assert(vec == expected);
+        const vector<int> expected_val = {5, 51, 512, 5121, 51212, 512121, 5121212};
+        assert(vec == expected_val);
 
         static_assert(static_cast<int>(cv_status::no_timeout) == 0);
         static_assert(static_cast<int>(cv_status::timeout) == 1);
@@ -291,6 +294,14 @@ int main() {
         assert(count(execution::par, begin(arr), end(arr), 0) == 4);
     }
 
+#ifdef _MSVC_INTERNAL_TESTING // TRANSITION, VSO-1543660 fixed in 17.3 Preview 3
+    {
+        puts("Testing <expected>.");
+        constexpr expected<double, int> test{unexpect, 42};
+        assert(test.error() == 42);
+    }
+#endif // ^^^ no workaround ^^^
+
     {
         puts("Testing <filesystem>.");
         constexpr wstring_view dot{L"."};
@@ -601,8 +612,8 @@ int main() {
             v.push_back(it->str());
         }
 
-        const vector<string> expected{"cute", "fluffy", "kittens"};
-        assert(v == expected);
+        const vector<string> expected_val{"cute", "fluffy", "kittens"};
+        assert(v == expected_val);
     }
 
     {
@@ -611,8 +622,8 @@ int main() {
         v.push_back(11);
         v.push_back(22);
         v.push_back(33);
-        constexpr int expected[]{11, 22, 33};
-        assert(equal(v.begin(), v.end(), begin(expected), end(expected)));
+        constexpr int expected_val[]{11, 22, 33};
+        assert(equal(v.begin(), v.end(), begin(expected_val), end(expected_val)));
     }
 
     {
@@ -682,8 +693,8 @@ int main() {
         odd.join();
         even.join();
 
-        const vector<int> expected = {5, 51, 512, 5121, 51212, 512121, 5121212};
-        assert(vec == expected);
+        const vector<int> expected_val = {5, 51, 512, 5121, 51212, 512121, 5121212};
+        assert(vec == expected_val);
     }
 
     {
@@ -706,31 +717,31 @@ int main() {
         char ibuffer[] = "1 2 3 4 5";
         ispanstream is{span<char>{ibuffer}};
         int read = 0;
-        for (int expected = 1; expected <= 5; ++expected) {
+        for (int expected_val = 1; expected_val <= 5; ++expected_val) {
             assert(is.good());
             is >> read;
-            assert(read == expected);
+            assert(read == expected_val);
         }
 
         const char const_buffer[] = "1 2 3 4 5";
         basic_ispanstream<char> is_const_buffer{span<const char>{const_buffer}};
         read = 0;
-        for (int expected = 1; expected <= 5; ++expected) {
+        for (int expected_val = 1; expected_val <= 5; ++expected_val) {
             assert(is_const_buffer.good());
             is_const_buffer >> read;
-            assert(read == expected);
+            assert(read == expected_val);
         }
 
-        const auto expected = "102030"sv;
+        const auto expected_val = "102030"sv;
         char obuffer[10];
         ospanstream os{span<char>{obuffer}};
         os << 10 << 20 << 30;
-        assert(equal(begin(os.span()), end(os.span()), begin(expected), end(expected)));
+        assert(equal(begin(os.span()), end(os.span()), begin(expected_val), end(expected_val)));
 
         char buffer[10];
         spanstream s{span<char>{buffer}};
         s << 10 << 20 << 30;
-        assert(equal(begin(s.span()), end(s.span()), begin(expected), end(expected)));
+        assert(equal(begin(s.span()), end(s.span()), begin(expected_val), end(expected_val)));
     }
 
     {
@@ -799,13 +810,13 @@ int main() {
             }};
             l.wait(); // wait for jt to generate the sequence
         } // destroying jt will ask it to stop
-        static constexpr int expected[]{1729, 5188, 2594, 1297, 3892, 1946, 973, 2920, 1460, 730, 365, 1096, 548, 274,
-            137, 412, 206, 103, 310, 155, 466, 233, 700, 350, 175, 526, 263, 790, 395, 1186, 593, 1780, 890, 445, 1336,
-            668, 334, 167, 502, 251, 754, 377, 1132, 566, 283, 850, 425, 1276, 638, 319, 958, 479, 1438, 719, 2158,
-            1079, 3238, 1619, 4858, 2429, 7288, 3644, 1822, 911, 2734, 1367, 4102, 2051, 6154, 3077, 9232, 4616, 2308,
-            1154, 577, 1732, 866, 433, 1300, 650, 325, 976, 488, 244, 122, 61, 184, 92, 46, 23, 70, 35, 106, 53, 160,
-            80, 40, 20, 10, 5, 16, 8, 4, 2, 1, -1000};
-        assert(equal(vec.begin(), vec.end(), begin(expected), end(expected)));
+        static constexpr int expected_val[]{1729, 5188, 2594, 1297, 3892, 1946, 973, 2920, 1460, 730, 365, 1096, 548,
+            274, 137, 412, 206, 103, 310, 155, 466, 233, 700, 350, 175, 526, 263, 790, 395, 1186, 593, 1780, 890, 445,
+            1336, 668, 334, 167, 502, 251, 754, 377, 1132, 566, 283, 850, 425, 1276, 638, 319, 958, 479, 1438, 719,
+            2158, 1079, 3238, 1619, 4858, 2429, 7288, 3644, 1822, 911, 2734, 1367, 4102, 2051, 6154, 3077, 9232, 4616,
+            2308, 1154, 577, 1732, 866, 433, 1300, 650, 325, 976, 488, 244, 122, 61, 184, 92, 46, 23, 70, 35, 106, 53,
+            160, 80, 40, 20, 10, 5, 16, 8, 4, 2, 1, -1000};
+        assert(equal(vec.begin(), vec.end(), begin(expected_val), end(expected_val)));
     }
 #endif // ^^^ no workaround ^^^
 

tests/std/tests/VSO_0157762_feature_test_macros/test.compile.pass.cpp

@@ -714,6 +714,20 @@ STATIC_ASSERT(__cpp_lib_execution == 201603L);
 #endif
 #endif
 
+#if _HAS_CXX23 && !defined(__EDG__) // TRANSITION, EDG concepts support
+#ifndef __cpp_lib_expected
+#error __cpp_lib_expected is not defined
+#elif __cpp_lib_expected != 202202L
+#error __cpp_lib_expected is not 202202L
+#else
+STATIC_ASSERT(__cpp_lib_expected == 202202L);
+#endif
+#else
+#ifdef __cpp_lib_expected
+#error __cpp_lib_expected is defined
+#endif
+#endif
+
 #ifndef __cpp_lib_experimental_erase_if
 #error __cpp_lib_experimental_erase_if is not defined
 #elif __cpp_lib_experimental_erase_if != 201411L

tests/std/tests/include_each_header_alone_matrix.lst

@@ -24,6 +24,7 @@ PM_CL="/DMEOW_HEADER=coroutine"
 PM_CL="/DMEOW_HEADER=deque"
 PM_CL="/DMEOW_HEADER=exception"
 PM_CL="/DMEOW_HEADER=execution"
+PM_CL="/DMEOW_HEADER=expected"
 PM_CL="/DMEOW_HEADER=filesystem"
 PM_CL="/DMEOW_HEADER=format"
 PM_CL="/DMEOW_HEADER=forward_list"