Add std::chrono::time_point constructor overloads and tests

cpp-overload-test/examples/stdcpp-time-point.rs

@@ -0,0 +1,50 @@
+//! Test c++ std::chrono::time_point
+//!
+//! Working overloads are in [time_point.rs]
+//!
+//! [time_point.rs]: ../src/stdcpp/time_point.rs
+
+#![feature(splat, tuple_trait)]
+#![allow(incomplete_features)]
+#![allow(unused_braces)]
+
+use splat_overload::overload;
+use std::ffi::c_longlong;
+
+/// A fake Rust wrapper representing a C++ time_point.
+///
+/// Using vector to represent the time point because this example only tests
+/// overload compatibility.
+#[expect(dead_code, reason = "Incompatible overloads can't be used")]
+struct StdTimePoint(Vec<c_longlong>);
+
+/// Workaround for testing identical time point types.
+///
+/// The converting constructor can accept a time point with the same
+/// duration type as the copy constructor.
+type SameTimePoint = StdTimePoint;
+
+// Constructors: new(...)
+//
+// When copy constructor and converting constructor receive the same
+// time_point type, their argument types become identical.
+//
+// c++ resolves this by preferring the non-template copy constructor.
+// Rust cannot represent both as separate overloads.
+
+overload! {
+    impl StdTimePoint {
+
+    /// Copy constructor
+    fn new(_other: &StdTimePoint) -> StdTimePoint {
+        todo!()
+    }
+
+    /// Converting constructor
+    fn new(_other: &SameTimePoint) -> StdTimePoint {
+        todo!()
+    }
+    }
+}
+
+pub fn main() {}

cpp-overload-test/examples/stdcpp-time-point.stderr

@@ -0,0 +1,18 @@
+error[E0119]: conflicting implementations of trait `NewArgs<StdTimePoint>` for type `(&StdTimePoint,)`
+  --> cpp-overload-test/examples/stdcpp-time-point.rs:35:1
+   |
+35 | / overload! {
+36 | |     impl StdTimePoint {
+37 | |
+38 | |     /// Copy constructor
+...  |
+48 | | }
+   | | ^
+   | | |
+   | |_first implementation here
+   |   conflicting implementation for `(&StdTimePoint,)`
+   |
+   = note: this error originates in the macro `overload` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+For more information about this error, try `rustc --explain E0119`.
+error: could not compile `cpp-overload-test` (example "stdcpp-time-point") due to 1 previous error

cpp-overload-test/src/lib.rs

@@ -11,6 +11,7 @@ pub mod stdcpp {
     // Add new modules for each type here, in alphabetical order.
     pub mod forward_list;
     pub mod hash;
+    pub mod time_point;
     pub mod unordered_map;
     pub mod unordered_multiset;
 }