Add the std test suite. (#498)

* Add tests/std.

* Update other files.

NOTICE.txt
Mention the LLVM Project, as its code appears
in tests/std/tests/P0220R1_optional/test.cpp and elsewhere.

azure-devops/enforce-clang-format.cmd
Process everything within tests. This includes libcxx, std, and tr1.

docs/cgmanifest.json
Update this file for Microsoft-internal purposes. (It records the commit
hashes of repos whose source code we've incorporated into our own repo.
For llvm-project, this is distinct from the submodule's current commit.)

tests/tr1/run.pl
Mention runbe.pl in lowercase, to match the file itself.

* Improve run.pl and runbe.pl comments.

NOTICE.txt

@@ -127,3 +127,13 @@ In addition, certain files include the notices provided below.
 //  Recipient is granted the right to make copies in any form for
 //  internal distribution and to freely use the information supplied
 //  in the creation of products supporting Unicode.
+
+----------------------
+
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//

azure-devops/enforce-clang-format.cmd

@@ -3,7 +3,7 @@
 "%1" "clang-format.exe -style=file -i" ^
 stl/inc ^
 stl/src ^
-tests/tr1 ^
+tests ^
 tools
 @echo If your build fails here, you need to format the following files with:
 @clang-format.exe --version

docs/cgmanifest.json

@@ -4,8 +4,8 @@
             "component": {
                 "type": "git",
                 "git": {
-                    "repositoryUrl": "https://github.com/ulfjack/ryu.git",
-                    "commitHash": "59661c3f883dfd39cef6dc8eaf2fcbaae53597e8"
+                    "repositoryUrl": "https://github.com/llvm/llvm-project.git",
+                    "commitHash": "6f0768f64da398d5103d39e83bdc66a5ffd6f0f6"
                 }
             }
         },
@@ -17,6 +17,15 @@
                     "commitHash": "07e85d10c051a0a53d522a28affb1fbc43fc24f0"
                 }
             }
+        },
+        {
+            "component": {
+                "type": "git",
+                "git": {
+                    "repositoryUrl": "https://github.com/ulfjack/ryu.git",
+                    "commitHash": "59661c3f883dfd39cef6dc8eaf2fcbaae53597e8"
+                }
+            }
         }
     ],
     "Version": 1

tests/std/include/constexpr_char_traits.hpp

@@ -0,0 +1,111 @@
+// Copyright (c) Microsoft Corporation.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+#pragma once
+#include <stdio.h>
+#include <wchar.h>
+
+struct constexpr_char_traits {
+    typedef char char_type;
+    typedef long int_type;
+    typedef long pos_type;
+    typedef long off_type;
+    typedef mbstate_t state_type;
+
+    static constexpr int compare(const char* first1, const char* first2, size_t count) {
+        for (; 0 < count; --count, ++first1, ++first2) {
+            if (!eq(*first1, *first2)) {
+                return lt(*first1, *first2) ? -1 : +1;
+            }
+        }
+
+        return 0;
+    }
+
+    static constexpr size_t length(const char* first) {
+        size_t count = 0;
+        for (; !eq(*first, char()); ++first) {
+            ++count;
+        }
+
+        return count;
+    }
+
+    static constexpr char* copy(char* first1, const char* first2, size_t count) {
+        char* next = first1;
+        for (; 0 < count; --count, ++next, ++first2) {
+            assign(*next, *first2);
+        }
+        return first1;
+    }
+
+    static constexpr char* _Copy_s(char* first1, size_t, const char* first2, size_t count) {
+        // let's just pretend :)
+        return copy(first1, first2, count);
+    }
+
+    static constexpr const char* find(const char* first, size_t count, const char ch) {
+        for (; 0 < count; --count, ++first) {
+            if (eq(*first, ch)) {
+                return first;
+            }
+        }
+
+        return nullptr;
+    }
+
+    static constexpr char* move(char* first1, const char* first2, size_t count) {
+        char* next = first1;
+        if (first2 < next && next < first2 + count) {
+            for (next += count, first2 += count; 0 < count; --count) {
+                assign(*--next, *--first2);
+            }
+        } else {
+            for (; 0 < count; --count, ++next, ++first2) {
+                assign(*next, *first2);
+            }
+        }
+        return first1;
+    }
+
+    static constexpr char* assign(char* first, size_t count, const char ch) {
+        char* next = first;
+        for (; 0 < count; --count, ++next) {
+            assign(*next, ch);
+        }
+
+        return first;
+    }
+
+    static constexpr void assign(char& left, const char right) noexcept {
+        left = right;
+    }
+
+    static constexpr bool eq(const char left, const char right) noexcept {
+        return left == right;
+    }
+
+    static constexpr bool lt(const char left, const char right) noexcept {
+        return left < right;
+    }
+
+    static constexpr char to_char_type(const int_type meta) noexcept {
+        return static_cast<char>(meta);
+    }
+
+    static constexpr int_type to_int_type(const char ch) noexcept {
+        return ch;
+    }
+
+    static constexpr bool eq_int_type(const int_type left, const int_type right) noexcept {
+        return left == right;
+    }
+
+    static constexpr int_type not_eof(const int_type meta) noexcept {
+        return meta != eof() ? meta : !eof();
+    }
+
+    static constexpr int_type eof() noexcept {
+        return EOF;
+    }
+};