More elegant solution for pure2-main-args.cpp2 (hsutter#949)

regression-tests/pure2-main-args.cpp2

@@ -1,10 +1,9 @@
 main: (args) = {
-    exe: std::string = args.argv[0];
-    pos:= exe.find_last_of("/\\");
-    if pos != std::string::npos {
-        pos++;
-        exe = exe.substr(pos, exe.size() - pos);
-    }
+    // Explicit call to string is necessary
+    // std::filesystem::path is base on and implicitly convertible to
+    // - std::string (on POSIX systems)
+    // - std::wstring (on Windows)
+    exe : _ = std::filesystem::path(args.argv[0]).filename().string();
     std::cout
         << "args.argc            is (args.argc)$\n"
         << "args.argv[0]         is (exe)$\n"

regression-tests/test-results/pure2-main-args.cpp

@@ -19,13 +19,12 @@ auto main(int const argc_, char** argv_) -> int;
 #line 1 "pure2-main-args.cpp2"
 auto main(int const argc_, char** argv_) -> int{
     auto const args = cpp2::make_args(argc_, argv_); 
-#line 2 "pure2-main-args.cpp2"
-    std::string exe {CPP2_ASSERT_IN_BOUNDS_LITERAL(args.argv, 0)}; 
-    auto pos {CPP2_UFCS(find_last_of)(exe, "/\\")}; 
-    if (pos != std::string::npos) {
-        ++pos;
-        exe = CPP2_UFCS(substr)(exe, pos, CPP2_UFCS(size)(exe) - std::move(pos));
-    }
+    // Explicit call to string is necessary
+    // std::filesystem::path is base on and implicitly convertible to
+    // - std::string (on POSIX systems)
+    // - std::wstring (on Windows)
+#line 6 "pure2-main-args.cpp2"
+    auto exe {CPP2_UFCS(string)(CPP2_UFCS(filename)(std::filesystem::path(CPP2_ASSERT_IN_BOUNDS_LITERAL(args.argv, 0))))}; 
     std::cout 
         << ("args.argc            is " + cpp2::to_string(args.argc) + "\n") 
         << ("args.argv[0]         is " + cpp2::to_string(std::move(exe)) + "\n");