Rework optional<T>

11 files changed, 154 insertions, 85 deletions

diff --git a/toolsrc/include/vcpkg_optional.h b/toolsrc/include/vcpkg_optional.h
index 7b935bea9..745377a82 100644
--- a/toolsrc/include/vcpkg_optional.h
+++ b/toolsrc/include/vcpkg_optional.h
@@ -1,5 +1,78 @@
 #pragma once
-#include <memory>
+#include "LineInfo.h"
+#include "vcpkg_Checks.h"
 
-template<class T>
-using optional = std::unique_ptr<T>;
+namespace vcpkg
+{
+    struct nullopt_t
+    {
+        explicit constexpr nullopt_t(int) {}
+    };
+
+    const static constexpr nullopt_t nullopt{ 0 };
+
+    template <class T>
+    class optional
+    {
+    public:
+        // Constructors are intentionally implicit
+        constexpr optional(nullopt_t) : m_is_present(false), m_t() { }
+
+        optional(const T& t) : m_is_present(true), m_t(t) { }
+
+        optional(T&& t) : m_is_present(true), m_t(std::move(t)) { }
+
+        T&& get_or_exit(const LineInfo& line_info) &&
+        {
+            this->exit_if_null(line_info);
+            return std::move(this->m_t);
+        }
+
+        const T& get_or_exit(const LineInfo& line_info) const &
+        {
+            this->exit_if_null(line_info);
+            return this->m_t;
+        }
+
+        constexpr explicit operator bool() const
+        {
+            return this->m_is_present;
+        }
+
+        constexpr bool has_value() const
+        {
+            return m_is_present;
+        }
+
+        template <class U>
+        T value_or(U&& default_value) const &
+        {
+            return bool(*this) ? this->m_t : static_cast<T>(std::forward<U>(default_value));
+        }
+
+        template <class U>
+        T value_or(U&& default_value) &&
+        {
+            return bool(*this) ? std::move(this->m_t) : static_cast<T>(std::forward<U>(default_value));
+        }
+
+        const T* get() const
+        {
+            return bool(*this) ? &this->m_t : nullptr;
+        }
+
+        T* get()
+        {
+            return bool(*this) ? &this->m_t : nullptr;
+        }
+
+    private:
+        void exit_if_null(const LineInfo& line_info) const
+        {
+            Checks::check_exit(line_info, this->m_is_present, "Value was null");
+        }
+
+        bool m_is_present;
+        T m_t;
+    };
+}
diff --git a/toolsrc/src/commands_ci.cpp b/toolsrc/src/commands_ci.cpp
index bfe87b35f..2d7016bcc 100644
--- a/toolsrc/src/commands_ci.cpp
+++ b/toolsrc/src/commands_ci.cpp
@@ -62,7 +62,11 @@ namespace vcpkg::Commands::CI
                 }
                 else if (action.plan.plan_type == install_plan_type::BUILD_AND_INSTALL)
                 {
-                    const BuildResult result = Commands::Build::build_package(*action.plan.source_pgh, action.spec, paths, paths.port_dir(action.spec), status_db);
+                    const BuildResult result = Commands::Build::build_package(action.plan.source_pgh.get_or_exit(VCPKG_LINE_INFO),
+                                                                              action.spec,
+                                                                              paths,
+                                                                              paths.port_dir(action.spec),
+                                                                              status_db);
                     timing.back() = build_timer.elapsed<std::chrono::milliseconds>().count();
                     results.back() = result;
                     if (result != BuildResult::SUCCEEDED)
@@ -77,7 +81,7 @@ namespace vcpkg::Commands::CI
                 else if (action.plan.plan_type == install_plan_type::INSTALL)
                 {
                     results.back() = BuildResult::SUCCEEDED;
-                    Install::install_package(paths, *action.plan.binary_pgh, &status_db);
+                    Install::install_package(paths, action.plan.binary_pgh.get_or_exit(VCPKG_LINE_INFO), &status_db);
                     System::println(System::color::success, "Package %s is installed from cache", action.spec);
                 }
                 else
diff --git a/toolsrc/src/commands_edit.cpp b/toolsrc/src/commands_edit.cpp
index d9cd627d2..4faf10bb9 100644
--- a/toolsrc/src/commands_edit.cpp
+++ b/toolsrc/src/commands_edit.cpp
@@ -22,9 +22,9 @@ namespace vcpkg::Commands::Edit
         if (env_EDITOR.empty())
         {
             const optional<std::wstring> env_EDITOR_optional = System::get_environmental_variable(L"EDITOR");
-            if (env_EDITOR_optional)
+            if (auto e = env_EDITOR_optional.get())
             {
-                env_EDITOR = *env_EDITOR_optional;
+                env_EDITOR = *e;
             }
         }
 
@@ -47,16 +47,16 @@ namespace vcpkg::Commands::Edit
             };
             for (auto&& keypath : regkeys)
             {
-                auto code_installpath = System::get_registry_string(HKEY_LOCAL_MACHINE, keypath, L"InstallLocation");
-                if (code_installpath)
+                const optional<std::wstring> code_installpath = System::get_registry_string(HKEY_LOCAL_MACHINE, keypath, L"InstallLocation");
+                if (auto c = code_installpath.get())
                 {
-                    auto p = fs::path(*code_installpath) / "Code.exe";
+                    auto p = fs::path(*c) / "Code.exe";
                     if (fs::exists(p))
                     {
                         env_EDITOR = p.native();
                         break;
                     }
-                    auto p_insiders = fs::path(*code_installpath) / "Code - Insiders.exe";
+                    auto p_insiders = fs::path(*c) / "Code - Insiders.exe";
                     if (fs::exists(p_insiders))
                     {
                         env_EDITOR = p_insiders.native();
diff --git a/toolsrc/src/commands_install.cpp b/toolsrc/src/commands_install.cpp
index 0b2062a7e..6c8ab8be4 100644
--- a/toolsrc/src/commands_install.cpp
+++ b/toolsrc/src/commands_install.cpp
@@ -216,7 +216,11 @@ namespace vcpkg::Commands::Install
                 }
                 else if (action.plan.plan_type == install_plan_type::BUILD_AND_INSTALL)
                 {
-                    const Build::BuildResult result = Commands::Build::build_package(*action.plan.source_pgh, action.spec, paths, paths.port_dir(action.spec), status_db);
+                    const Build::BuildResult result = Commands::Build::build_package(action.plan.source_pgh.get_or_exit(VCPKG_LINE_INFO),
+                                                                                     action.spec,
+                                                                                     paths,
+                                                                                     paths.port_dir(action.spec),
+                                                                                     status_db);
                     if (result != Build::BuildResult::SUCCEEDED)
                     {
                         System::println(System::color::error, Build::create_error_message(result, action.spec));
@@ -229,7 +233,7 @@ namespace vcpkg::Commands::Install
                 }
                 else if (action.plan.plan_type == install_plan_type::INSTALL)
                 {
-                    install_package(paths, *action.plan.binary_pgh, &status_db);
+                    install_package(paths, action.plan.binary_pgh.get_or_exit(VCPKG_LINE_INFO), &status_db);
                     System::println(System::color::success, "Package %s is installed", action.spec);
                 }
                 else
diff --git a/toolsrc/src/commands_integrate.cpp b/toolsrc/src/commands_integrate.cpp
index b72a7a483..9342fc71e 100644
--- a/toolsrc/src/commands_integrate.cpp
+++ b/toolsrc/src/commands_integrate.cpp
@@ -136,7 +136,8 @@ namespace vcpkg::Commands::Integrate
 
     static fs::path get_appdata_targets_path()
     {
-        return fs::path(*System::get_environmental_variable(L"LOCALAPPDATA")) / "vcpkg" / "vcpkg.user.targets";
+        static const fs::path local_app_data = fs::path(System::get_environmental_variable(L"LOCALAPPDATA").get_or_exit(VCPKG_LINE_INFO));
+        return local_app_data / "vcpkg" / "vcpkg.user.targets";
     }
 
     static void integrate_install(const vcpkg_paths& paths)
diff --git a/toolsrc/src/metrics.cpp b/toolsrc/src/metrics.cpp
index d0e20fe2d..2fdbe8f09 100644
--- a/toolsrc/src/metrics.cpp
+++ b/toolsrc/src/metrics.cpp
@@ -228,11 +228,7 @@ true
     std::wstring GetSQMUser()
     {
         auto hkcu_sqmclient = System::get_registry_string(HKEY_CURRENT_USER, LR"(Software\Microsoft\SQMClient)", L"UserId");
-
-        if (hkcu_sqmclient)
-            return std::move(*hkcu_sqmclient);
-        else
-            return L"{}";
+        return hkcu_sqmclient.value_or(L"{}");
     }
 
     void SetUserInformation(const std::string& user_id, const std::string& first_use_time)
diff --git a/toolsrc/src/vcpkg.cpp b/toolsrc/src/vcpkg.cpp
index 48c0c7e32..069d9a7c1 100644
--- a/toolsrc/src/vcpkg.cpp
+++ b/toolsrc/src/vcpkg.cpp
@@ -46,9 +46,9 @@ static void inner(const vcpkg_cmd_arguments& args)
     else
     {
         const optional<std::wstring> vcpkg_root_dir_env = System::get_environmental_variable(L"VCPKG_ROOT");
-        if (vcpkg_root_dir_env)
+        if (auto v = vcpkg_root_dir_env.get())
         {
-            vcpkg_root_dir = fs::absolute(*vcpkg_root_dir_env);
+            vcpkg_root_dir = fs::absolute(*v);
         }
         else
         {
@@ -77,9 +77,9 @@ static void inner(const vcpkg_cmd_arguments& args)
     else
     {
         const optional<std::wstring> vcpkg_default_triplet_env = System::get_environmental_variable(L"VCPKG_DEFAULT_TRIPLET");
-        if (vcpkg_default_triplet_env)
+        if (auto v = vcpkg_default_triplet_env.get())
         {
-            default_target_triplet = triplet::from_canonical_name(Strings::utf16_to_utf8(*vcpkg_default_triplet_env));
+            default_target_triplet = triplet::from_canonical_name(Strings::utf16_to_utf8(*v));
         }
         else
         {
diff --git a/toolsrc/src/vcpkg_Dependencies.cpp b/toolsrc/src/vcpkg_Dependencies.cpp
index 4233279cf..dad144cfb 100644
--- a/toolsrc/src/vcpkg_Dependencies.cpp
+++ b/toolsrc/src/vcpkg_Dependencies.cpp
@@ -9,7 +9,7 @@
 
 namespace vcpkg::Dependencies
 {
-    install_plan_action::install_plan_action() : plan_type(install_plan_type::UNKNOWN), binary_pgh(nullptr), source_pgh(nullptr)
+    install_plan_action::install_plan_action() : plan_type(install_plan_type::UNKNOWN), binary_pgh(nullopt), source_pgh(nullopt)
     {
     }
 
@@ -68,7 +68,7 @@ namespace vcpkg::Dependencies
             auto it = status_db.find(spec);
             if (it != status_db.end() && (*it)->want == want_t::install)
             {
-                was_examined.emplace(spec, install_plan_action{install_plan_type::ALREADY_INSTALLED, nullptr, nullptr});
+                was_examined.emplace(spec, install_plan_action{install_plan_type::ALREADY_INSTALLED, nullopt, nullopt });
                 continue;
             }
 
@@ -76,7 +76,7 @@ namespace vcpkg::Dependencies
             if (BinaryParagraph* bpgh = maybe_bpgh.get())
             {
                 process_dependencies(bpgh->depends);
-                was_examined.emplace(spec, install_plan_action{install_plan_type::INSTALL, std::make_unique<BinaryParagraph>(std::move(*bpgh)), nullptr});
+                was_examined.emplace(spec, install_plan_action{install_plan_type::INSTALL, std::move(*bpgh), nullopt });
                 continue;
             }
 
@@ -84,7 +84,7 @@ namespace vcpkg::Dependencies
             SourceParagraph* spgh = maybe_spgh.get();
             Checks::check_exit(VCPKG_LINE_INFO, spgh != nullptr, "Cannot find package %s", spec.name());
             process_dependencies(filter_dependencies(spgh->depends, spec.target_triplet()));
-            was_examined.emplace(spec, install_plan_action{install_plan_type::BUILD_AND_INSTALL, nullptr, std::make_unique<SourceParagraph>(std::move(*spgh))});
+            was_examined.emplace(spec, install_plan_action{install_plan_type::BUILD_AND_INSTALL, nullopt, std::move(*spgh)});
         }
 
         std::vector<package_spec_with_install_plan> ret;
diff --git a/toolsrc/src/vcpkg_Environment.cpp b/toolsrc/src/vcpkg_Environment.cpp
index ca68498ef..d28a25017 100644
--- a/toolsrc/src/vcpkg_Environment.cpp
+++ b/toolsrc/src/vcpkg_Environment.cpp
@@ -19,14 +19,14 @@ namespace vcpkg::Environment
     static optional<fs::path> find_vs2015_installation_instance()
     {
         const optional<std::wstring> vs2015_cmntools_optional = System::get_environmental_variable(L"VS140COMNTOOLS");
-        if (!vs2015_cmntools_optional)
+        if (auto v = vs2015_cmntools_optional.get())
         {
-            return nullptr;
+            static const fs::path vs2015_cmntools = fs::path(*v).parent_path(); // The call to parent_path() is needed because the env variable has a trailing backslash
+            static const fs::path vs2015_path = vs2015_cmntools.parent_path().parent_path();
+            return vs2015_path;
         }
 
-        static const fs::path vs2015_cmntools = fs::path(*vs2015_cmntools_optional).parent_path(); // The call to parent_path() is needed because the env variable has a trailing backslash
-        static const fs::path vs2015_path = vs2015_cmntools.parent_path().parent_path();
-        return std::make_unique<fs::path>(vs2015_path);
+        return nullopt;
     }
 
     static const optional<fs::path>& get_VS2015_installation_instance()
@@ -69,9 +69,9 @@ namespace vcpkg::Environment
 
         // VS2015
         const optional<fs::path>& vs_2015_installation_instance = get_VS2015_installation_instance();
-        if (vs_2015_installation_instance)
+        if (auto v = vs_2015_installation_instance.get())
         {
-            const fs::path vs2015_dumpbin_exe = *vs_2015_installation_instance / "VC" / "bin" / "dumpbin.exe";
+            const fs::path vs2015_dumpbin_exe = *v / "VC" / "bin" / "dumpbin.exe";
             paths_examined.push_back(vs2015_dumpbin_exe);
             if (fs::exists(vs2015_dumpbin_exe))
             {
@@ -112,9 +112,9 @@ namespace vcpkg::Environment
 
         // VS2015
         const optional<fs::path>& vs_2015_installation_instance = get_VS2015_installation_instance();
-        if (vs_2015_installation_instance)
+        if (auto v = vs_2015_installation_instance.get())
         {
-            const fs::path vs2015_vcvarsall_bat = *vs_2015_installation_instance / "VC" / "vcvarsall.bat";
+            const fs::path vs2015_vcvarsall_bat = *v / "VC" / "vcvarsall.bat";
 
             paths_examined.push_back(vs2015_vcvarsall_bat);
             if (fs::exists(vs2015_vcvarsall_bat))
@@ -138,50 +138,37 @@ namespace vcpkg::Environment
         return vcvarsall_bat;
     }
 
-    static fs::path find_ProgramFiles()
-    {
-        const optional<std::wstring> program_files = System::get_environmental_variable(L"PROGRAMFILES");
-        Checks::check_exit(VCPKG_LINE_INFO, program_files.get() != nullptr, "Could not detect the PROGRAMFILES environmental variable");
-        return *program_files;
-    }
-
     static const fs::path& get_ProgramFiles()
     {
-        static const fs::path p = find_ProgramFiles();
+        static const fs::path p = System::get_environmental_variable(L"PROGRAMFILES").get_or_exit(VCPKG_LINE_INFO);
         return p;
     }
 
-    static fs::path find_ProgramFiles_32_bit()
-    {
-        const optional<std::wstring> program_files_X86 = System::get_environmental_variable(L"ProgramFiles(x86)");
-        if (program_files_X86)
-        {
-            return *program_files_X86;
-        }
-
-        return get_ProgramFiles();
-    }
-
     const fs::path& get_ProgramFiles_32_bit()
     {
-        static const fs::path p = find_ProgramFiles_32_bit();
+        static const fs::path p = []() -> fs::path
+            {
+                auto value = System::get_environmental_variable(L"ProgramFiles(x86)");
+                if (auto v = value.get())
+                {
+                    return std::move(*v);
+                }
+                return get_ProgramFiles();
+            }();
         return p;
     }
 
-    static fs::path find_ProgramFiles_platform_bitness()
-    {
-        const optional<std::wstring> program_files_W6432 = System::get_environmental_variable(L"ProgramW6432");
-        if (program_files_W6432)
-        {
-            return *program_files_W6432;
-        }
-
-        return get_ProgramFiles();
-    }
-
     const fs::path& get_ProgramFiles_platform_bitness()
     {
-        static const fs::path p = find_ProgramFiles_platform_bitness();
+        static const fs::path p = []() -> fs::path
+            {
+                auto value = System::get_environmental_variable(L"ProgramW6432");
+                if (auto v = value.get())
+                {
+                    return std::move(*v);
+                }
+                return get_ProgramFiles();
+            }();
         return p;
     }
 }
diff --git a/toolsrc/src/vcpkg_System.cpp b/toolsrc/src/vcpkg_System.cpp
index 5518e4c45..221a201ed 100644
--- a/toolsrc/src/vcpkg_System.cpp
+++ b/toolsrc/src/vcpkg_System.cpp
@@ -15,7 +15,7 @@ namespace vcpkg::System
 
     int cmd_execute_clean(const cwstring_view cmd_line)
     {
-        static const std::wstring system_root = *get_environmental_variable(L"SystemRoot");
+        static const std::wstring system_root = get_environmental_variable(L"SystemRoot").get_or_exit(VCPKG_LINE_INFO);
         static const std::wstring system_32 = system_root + LR"(\system32)";
         static const std::wstring new_PATH = Strings::wformat(LR"(Path=%s;%s;%s\WindowsPowerShell\v1.0\)", system_32, system_root, system_32);
 
@@ -69,8 +69,9 @@ namespace vcpkg::System
 
         for (auto&& env_wstring : env_wstrings)
         {
-            auto v = System::get_environmental_variable(env_wstring.c_str());
-            if (v == nullptr || v->empty())
+            const optional<std::wstring> value = System::get_environmental_variable(env_wstring.c_str());
+            auto v = value.get();
+            if (!v || v->empty())
                 continue;
 
             env_wstring.push_back(L'=');
@@ -164,14 +165,14 @@ namespace vcpkg::System
     {
         auto sz = GetEnvironmentVariableW(varname, nullptr, 0);
         if (sz == 0)
-            return nullptr;
+            return nullopt;
 
         auto ret = std::make_unique<std::wstring>(sz, L'\0');
         Checks::check_exit(VCPKG_LINE_INFO, MAXDWORD >= ret->size());
         auto sz2 = GetEnvironmentVariableW(varname, ret->data(), static_cast<DWORD>(ret->size()));
         Checks::check_exit(VCPKG_LINE_INFO, sz2 + 1 == sz);
         ret->pop_back();
-        return ret;
+        return *ret.release();
     }
 
     void set_environmental_variable(const cwstring_view varname, const cwstring_view varvalue) noexcept
@@ -189,21 +190,21 @@ namespace vcpkg::System
         HKEY k = nullptr;
         LSTATUS ec = RegOpenKeyExW(base, subKey, NULL, KEY_READ, &k);
         if (ec != ERROR_SUCCESS)
-            return nullptr;
+            return nullopt;
 
         DWORD dwBufferSize = 0;
         DWORD dwType = 0;
         auto rc = RegQueryValueExW(k, valuename, nullptr, &dwType, nullptr, &dwBufferSize);
         if (rc != ERROR_SUCCESS || !is_string_keytype(dwType) || dwBufferSize == 0 || dwBufferSize % sizeof(wchar_t) != 0)
-            return nullptr;
+            return nullopt;
         std::wstring ret;
         ret.resize(dwBufferSize / sizeof(wchar_t));
 
         rc = RegQueryValueExW(k, valuename, nullptr, &dwType, reinterpret_cast<LPBYTE>(ret.data()), &dwBufferSize);
         if (rc != ERROR_SUCCESS || !is_string_keytype(dwType) || dwBufferSize != sizeof(wchar_t) * ret.size())
-            return nullptr;
+            return nullopt;
 
         ret.pop_back(); // remove extra trailing null byte
-        return std::make_unique<std::wstring>(std::move(ret));
+        return ret;
     }
 }
diff --git a/toolsrc/src/vcpkg_paths.cpp b/toolsrc/src/vcpkg_paths.cpp
index 732c4a4fc..86106028a 100644
--- a/toolsrc/src/vcpkg_paths.cpp
+++ b/toolsrc/src/vcpkg_paths.cpp
@@ -47,10 +47,10 @@ namespace vcpkg
 
         if (it != candidate_paths.cend())
         {
-            return std::make_unique<fs::path>(std::move(*it));
+            return std::move(*it);
         }
 
-        return nullptr;
+        return nullopt;
     }
 
     static std::vector<fs::path> find_from_PATH(const std::wstring& name)
@@ -101,9 +101,10 @@ namespace vcpkg
         candidate_paths.push_back(Environment::get_ProgramFiles_platform_bitness() / "CMake" / "bin" / "cmake.exe");
         candidate_paths.push_back(Environment::get_ProgramFiles_32_bit() / "CMake" / "bin");
 
-        if (auto ret = find_if_has_equal_or_greater_version(candidate_paths, version_check_arguments, expected_version))
+        const optional<fs::path> path = find_if_has_equal_or_greater_version(candidate_paths, version_check_arguments, expected_version);
+        if (auto p = path.get())
         {
-            return *ret;
+            return *p;
         }
 
         return fetch_dependency(scripts_folder, L"cmake", downloaded_copy);
@@ -121,9 +122,10 @@ namespace vcpkg
         candidate_paths.push_back(downloaded_copy);
         candidate_paths.insert(candidate_paths.end(), from_path.cbegin(), from_path.cend());
 
-        if (auto ret = find_if_has_equal_or_greater_version(candidate_paths, version_check_arguments, expected_version))
+        auto path = find_if_has_equal_or_greater_version(candidate_paths, version_check_arguments, expected_version);
+        if (auto p = path.get())
         {
-            return *ret;
+            return *p;
         }
 
         return fetch_dependency(scripts_folder, L"nuget", downloaded_copy);
@@ -143,9 +145,10 @@ namespace vcpkg
         candidate_paths.push_back(Environment::get_ProgramFiles_platform_bitness() / "git" / "cmd" / "git.exe");
         candidate_paths.push_back(Environment::get_ProgramFiles_32_bit() / "git" / "cmd" / "git.exe");
 
-        if (auto ret = find_if_has_equal_or_greater_version(candidate_paths, version_check_arguments, expected_version))
+        const optional<fs::path> path = find_if_has_equal_or_greater_version(candidate_paths, version_check_arguments, expected_version);
+        if (auto p = path.get())
         {
-            return *ret;
+            return *p;
         }
 
         return fetch_dependency(scripts_folder, L"git", downloaded_copy);