Replace boost::filesystem with std (#6432)

unit_tests/common/temporary_file.hpp

@@ -1,16 +1,39 @@
 #ifndef UNIT_TESTS_TEMPORARY_FILE_HPP
 #define UNIT_TESTS_TEMPORARY_FILE_HPP
 
-#include <boost/filesystem.hpp>
+#include <cstdlib>
+#include <filesystem>
+#include <random>
+#include <string>
+
+inline std::string random_string(std::string::size_type length)
+{
+    static auto &chrs = "0123456789"
+                        "abcdefghijklmnopqrstuvwxyz"
+                        "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
+
+    thread_local static std::mt19937 rg{std::random_device{}()};
+    thread_local static std::uniform_int_distribution<std::string::size_type> pick(
+        0, sizeof(chrs) - 2);
+
+    std::string s;
+    s.reserve(length);
+
+    while (length--)
+    {
+        s += chrs[pick(rg)];
+    }
+    return s;
+}
 
 struct TemporaryFile
 {
-    TemporaryFile() : path(boost::filesystem::unique_path()) {}
+    TemporaryFile() : path(std::filesystem::temp_directory_path() / random_string(8)) {}
     TemporaryFile(const std::string &path) : path(path) {}
 
-    ~TemporaryFile() { boost::filesystem::remove(path); }
+    ~TemporaryFile() { std::filesystem::remove(path); }
 
-    boost::filesystem::path path;
+    std::filesystem::path path;
 };
 
 #endif // UNIT_TESTS_TEMPORARY_FILE_HPP