refactor: Replace phmap with boost.unordered

Minimize dependence on external projects by dropping `parallel-hashmap`
and replacing it with `boost-unordered`. `boost-unordered` provides a
fast `unordered_map` implementation since `1.80` and an even faster
`unordered_flat_map` since `1.81`. Therefore we bump the required
version.

Properly assert the required version during CMake configuration as well
as during transitive dependency lookup.

CMakeLists.txt

@@ -58,14 +58,14 @@ mark_as_advanced(DPLX_DP_USE_BRANCHING_INTEGER_ENCODER)
 
 set(Boost_NO_WARN_NEW_VERSIONS ON)
 
-find_package(concrete CONFIG REQUIRED)
+find_package(concrete 0.0 CONFIG REQUIRED)
 
-find_package(fmt CONFIG REQUIRED)
+find_package(fmt 9 CONFIG REQUIRED)
 
 find_package(status-code CONFIG REQUIRED)
 find_package(outcome CONFIG REQUIRED)
 
-find_package(Boost 1.71 REQUIRED)
+find_package(Boost 1.81 REQUIRED)
 
 find_package(yaml-cpp CONFIG)
 set_package_properties(yaml-cpp PROPERTIES

src/dplx/dp/detail/workaround.hpp

@@ -7,6 +7,7 @@
 
 #pragma once
 
+#include <dplx/predef/library/std.h>
 #include <dplx/predef/version_number.h>
 #include <dplx/predef/workaround.h>
 
@@ -27,3 +28,10 @@
     DPLX_XDEF_WORKAROUND_TESTED_AT(DPLX_DP_DISABLE_WORKAROUNDS,                \
                                    DPLX_DP_FLAG_OUTDATED_WORKAROUNDS, symbol,  \
                                    major, minor, patch)
+
+////////////////////////////////////////////////////////////////////////////////
+
+// libstdc++ fails to forward pair members during uses_allocator construction
+// see https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108952
+#define DPLX_DP_WORKAROUND_ISSUE_LIBSTDCPP_108952                              \
+    DPLX_DP_WORKAROUND_TESTED_AT(DPLX_LIB_STD_GNU, 12, 2, 0)

src/dplx/dp/state.hpp

@@ -11,11 +11,12 @@
 #include <memory_resource>
 #include <utility>
 
-#include <parallel_hashmap/phmap.h>
+#include <boost/unordered/unordered_flat_map.hpp>
 
 #include <dplx/cncr/utils.hpp>
 #include <dplx/cncr/uuid.hpp>
 
+#include <dplx/dp/detail/workaround.hpp>
 #include <dplx/dp/fwd.hpp>
 
 namespace dplx::dp::detail
@@ -121,6 +122,13 @@ class unique_erased_state_ptr
         , mDelete(std::exchange(other.mDelete, nullptr))
     {
     }
+#if DPLX_DP_WORKAROUND_ISSUE_LIBSTDCPP_108952
+    constexpr unique_erased_state_ptr(unique_erased_state_ptr &other) noexcept
+        : mObj(std::exchange(other.mObj, nullptr))
+        , mDelete(std::exchange(other.mDelete, nullptr))
+    {
+    }
+#endif
     constexpr auto operator=(unique_erased_state_ptr &&other) noexcept
             -> unique_erased_state_ptr &
     {
@@ -195,7 +203,7 @@ namespace dplx::dp::detail
 {
 
 template <typename Key, typename T>
-using flat_hash_map = phmap::flat_hash_map<
+using flat_hash_map = boost::unordered_flat_map<
         Key,
         T,
         std::hash<Key>,
@@ -278,14 +286,14 @@ class state_store
     auto emplace(state_key<StateT> const &key, Args &&...args)
             -> std::pair<StateT *, bool>
     {
-        auto const h = mImpl.hash(key.value);
-        if (auto it = mImpl.find(key.value, h); it != mImpl.end())
+        auto hint = mImpl.find(key.value);
+        if (hint != mImpl.end())
         {
             // this way, we don't need to allocate if key already has a value
-            return {it->second.template get<StateT>(), false};
+            return {hint->second.template get<StateT>(), false};
         }
-        auto [it, emplaced] = mImpl.emplace_with_hash(
-                h, key.value,
+        auto it = mImpl.emplace_hint(
+                hint, key.value,
                 detail::allocate_state<StateT, allocator_type>(
                         mImpl.get_allocator(), static_cast<Args &&>(args)...));
         return {it->second.template get<StateT>(), true};
@@ -401,15 +409,13 @@ class link_store
     template <state_link T>
     auto replace(state_link_key<T> const &key, T value) -> T
     {
-        auto const h = mImpl.hash(key.value);
-        auto it = mImpl.find(key.value, h);
+        auto it = mImpl.find(key.value);
         if (it == mImpl.end())
         {
             if (value != T{})
             {
-                mImpl.emplace_with_hash(
-                        h, key.value,
-                        detail::erasure_cast<erased_type, T>(value));
+                mImpl.emplace_hint(it, key.value,
+                                   detail::erasure_cast<erased_type, T>(value));
             }
             return T{};
         }

tools/deeppack-config.cmake.in

@@ -1,10 +1,11 @@
 @PACKAGE_INIT@
 
 include(CMakeFindDependencyMacro)
-find_dependency(Boost)
-find_dependency(fmt)
+find_dependency(Boost 1.81)
+find_dependency(fmt 9)
+find_dependency(status-code)
 find_dependency(outcome)
-find_dependency(concrete)
+find_dependency(concrete 0.0)
 
 include("${CMAKE_CURRENT_LIST_DIR}/deeppack-targets.cmake")
 

vcpkg.json

@@ -7,10 +7,10 @@
         "boost-endian",
         "boost-container",
         "boost-mp11",
+        "boost-unordered",
         "concrete",
         "fmt",
         "outcome",
-        "parallel-hashmap",
         "status-code"
     ],
     "features": {