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Added some examples of what metaclass generation might look like
1 parent 4b0a3e3 commit 698e566

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+312
-1
lines changed

‎CMakeLists.txt‎

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@@ -13,4 +13,5 @@ endif()
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enable_testing()
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add_subdirectory(tests)
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add_subdirectory(include/scl)
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add_subdirectory(include/scl/utils)
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add_subdirectory(include/scl/utils)
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add_subdirectory(include/scl/meta)

‎include/scl/meta/CMakeLists.txt‎

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set(CMAKE_CXX_STANDARD 23)
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set(CMAKE_CXX_STANDARD_REQUIRED ON)
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message(STATUS META)
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include(../../../cmake/icm_build_failure_testing.cmake)
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include(../../../cmake/icm_testing.cmake)
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# Global include for icm based tests
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include_directories("../../include")
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#if (CMAKE_CXX_COMPILER_ID STREQUAL "Clang"
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# OR CMAKE_CXX_COMPILER_ID STREQUAL "AppleClang")
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# set (ERROR_STRING "does not satisfy 'send'")
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#elseif (CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
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# set (ERROR_STRING "constraints not satisfied")
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#elseif (CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
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# # using Visual Studio C++
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#endif()
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icm_glob_build_failure_tests(
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PATTERN build_fail_*
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ERROR_MATCHES "error: "
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)
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file(GLOB test_files LIST_DIRECTORIES false "${CMAKE_CURRENT_SOURCE_DIR}" *.test.cpp)
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list(FILTER test_files EXCLUDE REGEX "build_")
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message(test_files: ${test_files})
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foreach(test_file ${test_files})
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get_filename_component(name_without_extension "${test_file}" NAME_WE)
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icm_add_test(
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NAME ${name_without_extension}
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SOURCES ${test_file})
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if(${test_file} MATCHES fail_*)
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set_tests_properties(${name_without_extension} PROPERTIES
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WILL_FAIL TRUE)
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endif()
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endforeach()

‎include/scl/meta/build_fail_cow_vector_address.test.cpp‎

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//
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// Created by David Rowland on 11/02/2025.
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//
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#include "cow_vector.h"
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int main()
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{
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auto vec = cow_vector<int>();
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[[maybe_unused]] auto vec_p = &vec;
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}

‎include/scl/meta/build_fail_cow_vector_heap.test.cpp‎

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//
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// Created by David Rowland on 11/02/2025.
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//
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#include "cow_vector.h"
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int main()
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{
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[[maybe_unused]] auto vec = std::make_unique<cow_vector<int>>();
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}

‎include/scl/meta/cow_vector.h‎

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//
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// Created by David Rowland on 17/06/2025.
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//
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#pragma once
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#define DATA_RACE_DETECTED { std::println ("ERROR: data race detected"); std::exit(1); }
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#include "../utils/data_race_checker.test.h"
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void check(bool x)
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{
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assert (x);
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if (! x)
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std::exit(1);
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}
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template<typename T>
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class cow_vector
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{
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public:
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cow_vector()
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: data (std::make_shared<test_vector<T>>())
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{}
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cow_vector (const cow_vector& o) {
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scl::scoped_check<scl::check_type::read> _ (scl::data_race_registry<>::get_state (std::addressof (o)));
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data = o.data;
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}
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cow_vector& operator= (const cow_vector& o) {
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scl::scoped_check<scl::check_type::read> _ (scl::data_race_registry<>::get_state (std::addressof (o)));
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data = o.data;
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return *this;
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}
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void clear() {
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scl::scoped_check<scl::check_type::write> _ (scl::data_race_registry<>::get_state (this));
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copy_if_shared();
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data->clear();
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}
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void push_back(const T& value) {
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scl::scoped_check<scl::check_type::write> _ (scl::data_race_registry<>::get_state (this));
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copy_if_shared();
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data->push_back(value);
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}
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T& back() {
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scl::scoped_check<scl::check_type::read> _ (scl::data_race_registry<>::get_state (this));
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return data->back();
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}
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size_t size() const {
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scl::scoped_check<scl::check_type::read> _ (scl::data_race_registry<>::get_state (this));
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return data->size();
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}
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bool empty() const {
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scl::scoped_check<scl::check_type::read> _ (scl::data_race_registry<>::get_state (this));
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return data->empty();
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}
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// Prevents dynamic allocation
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void* operator new(size_t) = delete;
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void* operator new[](size_t) = delete;
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// Prevents taking the address
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cow_vector<T>* operator&() = delete;
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const cow_vector<T>* operator&() const = delete;
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class inout
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{
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public:
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~inout()
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{
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*cow_vector_arg = cow_vector; // copy back modifications
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}
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void push_back(const T& value) {
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cow_vector.push_back(value);
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}
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// reflect to generate and forward all
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// functions to internal copy
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private:
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friend class cow_vector;
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cow_vector* cow_vector_arg; // pointer to original
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cow_vector cow_vector; // copy, safe to modify
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inout (class cow_vector* v)
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: cow_vector_arg (v),
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cow_vector (*v)
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{}
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};
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inout make_inout()
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{
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return inout (this);
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}
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private:
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void copy_if_shared() {
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scl::scoped_check<scl::check_type::write> _ (scl::data_race_registry<>::get_state (this));
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if (data.use_count() > 1) {
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data = std::make_shared<test_vector<T>> (*data);
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}
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}
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std::shared_ptr<test_vector<T>> data;
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};

‎include/scl/meta/fail_cow_vector_addressof.test.cpp‎

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//
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// Created by David Rowland on 11/02/2025.
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//
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#include "cow_vector.h"
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#include <latch>
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using namespace std::literals;
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void push_42 (cow_vector<int>* v) {
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std::latch latch (1);
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std::thread t ([v, &latch] mutable
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{
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latch.count_down();
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auto vec = *v;
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[[maybe_unused]] auto vec2 = vec;
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});
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latch.wait();
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v->push_back (42);
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t.join();
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}
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int main()
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{
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for (;;)
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{
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cow_vector<int> vec;
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vec.push_back (1);
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push_42 (std::addressof (vec));
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check(vec.back() == 42);
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}
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}

‎include/scl/meta/pass_cow_vector.test.cpp‎

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//
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// Created by David Rowland on 11/02/2025.
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//
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#include "cow_vector.h"
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int main()
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{
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cow_vector<int> vec;
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vec.push_back (1);
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vec.push_back (2);
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vec.push_back (3);
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check(vec.size() == 3uz);
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[vec2 = vec] mutable {
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vec2.push_back (42);
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check(vec2.size() == 4uz);
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vec2.push_back (43);
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check(vec2.size() == 5uz);
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vec2.push_back (44);
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check(vec2.size() == 6uz);
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}();
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check(vec.size() == 3uz);
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}

‎include/scl/meta/pass_cow_vector_inout.test.cpp‎

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//
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// Created by David Rowland on 11/02/2025.
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//
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#include "cow_vector.h"
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#include <latch>
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void push_42 (cow_vector<int>::inout v)
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{
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std::latch latch (1);
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std::thread t ([v, &latch] mutable
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{
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latch.count_down();
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auto vec = v;
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[[maybe_unused]] auto vec2 = vec;
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});
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latch.wait();
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v.push_back (42);
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t.join();
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}
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int main()
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{
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for (int i = 0; i < 100'000; ++i)
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{
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cow_vector<int> vec;
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vec.push_back (1);
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push_42 (vec.make_inout());
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check(vec.back() == 42);
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}
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}

‎include/scl/meta/pass_cow_vector_thread.test.cpp‎

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//
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// Created by David Rowland on 11/02/2025.
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//
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#include "cow_vector.h"
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#include <latch>
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void push_42 (cow_vector<int> v) {
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v.push_back (42);
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}
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int main()
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{
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using namespace std::literals;
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for (int i = 0; i < 100'000; ++i)
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{
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cow_vector<int> vec;
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std::latch latch (1);
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std::thread t ([vec, &latch] mutable
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{
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latch.count_down();
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vec.push_back(43);
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check(vec.back() == 43);
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});
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latch.wait();
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push_42 (vec);
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check(vec.empty());
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t.join();
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}
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}

‎include/scl/utils/data_race_checker.h‎

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* is quicker than getting the thread ID. A rudimentary benchmark (below) shows
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* getting this is the same on clang 17 and GCC 13.2:
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* https://quick-bench.com/q/iTnk1X3mGYUQ2yryuK_Wcg6JJ6Q
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* https://quick-bench.com/q/NdoJqZN3jp93lHbuxmbLg9xZUJU
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*
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* When detecting if there is a data-race, comparing thread IDs is very quick. I
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* would expect finding if two addresses are on the same stack is more costly as

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