Add Vec<T>::truncate to C++ API

Based on the model of #951, which added `Vec<T>::clear`. The `truncate`
method is the more general form of clear.

(If we wanted to, we could delete the binding for `clear` and implement
`clear` as a call to `truncate(0)` on the C++ side, but seemed worth
leaving in in case the Rust `clear` implementation one day gets
smarter.)

1 files changed, 6 insertions, 0 deletions

diff --git a/src/cxx.cc b/src/cxx.cc
index 4bdbd583..7fffa834 100644
--- a/src/cxx.cc
+++ b/src/cxx.cc
@@ -569,6 +569,8 @@ static_assert(sizeof(std::string) <= kMaxExpectedWordsInString * sizeof(void *),
       rust::Vec<CXX_TYPE> *ptr, std::size_t new_cap) noexcept;                 \
   void cxxbridge1$rust_vec$##RUST_TYPE##$set_len(rust::Vec<CXX_TYPE> *ptr,     \
                                                  std::size_t len) noexcept;    \
+  void cxxbridge1$rust_vec$##RUST_TYPE##$truncate(rust::Vec<CXX_TYPE> *ptr,    \
+                                                  std::size_t len) noexcept;   \
   void cxxbridge1$rust_vec$##RUST_TYPE##$clear(                                \
       rust::Vec<CXX_TYPE> *ptr) noexcept;
 
@@ -602,6 +604,10 @@ static_assert(sizeof(std::string) <= kMaxExpectedWordsInString * sizeof(void *),
     cxxbridge1$rust_vec$##RUST_TYPE##$set_len(this, len);                      \
   }                                                                            \
   template <>                                                                  \
+  void Vec<CXX_TYPE>::truncate(std::size_t len) {                              \
+    cxxbridge1$rust_vec$##RUST_TYPE##$truncate(this, len);                     \
+  }                                                                            \
+  template <>                                                                  \
   void Vec<CXX_TYPE>::clear() {                                                \
     cxxbridge1$rust_vec$##RUST_TYPE##$clear(this);                             \
   }