Move Rust symbols required by C++ to a separate Buck target

Closes #168.

15 files changed, 153 insertions, 117 deletions

diff --git a/BUCK b/BUCK
index 2339f714..acf3a4c9 100644
--- a/BUCK
+++ b/BUCK
@@ -1,7 +1,8 @@
 rust_library(
     name = "cxx",
-    srcs = glob(["src/**"]),
+    srcs = glob(["src/**"], exclude = ["src/symbols/**"]),
     visibility = ["PUBLIC"],
+    rustc_flags = ["--cfg", "no_export_symbols"],
     deps = [
         ":core",
         ":macro",
@@ -33,6 +34,13 @@ cxx_library(
         "cxx.h": "include/cxx.h",
     },
     exported_linker_flags = ["-lstdc++"],
+    deps = [":symbols"],
+)
+
+rust_library(
+    name = "symbols",
+    srcs = glob(["src/macros/**", "src/symbols/**"]),
+    crate_root = "src/symbols/lib.rs",
 )
 
 rust_library(
diff --git a/src/exception.rs b/src/exception.rs
index 52f0cf6d..125e4843 100644
--- a/src/exception.rs
+++ b/src/exception.rs
@@ -1,5 +1,4 @@
 use std::fmt::{self, Debug, Display};
-use std::slice;
 
 /// Exception thrown from an `extern "C"` function.
 #[derive(Debug)]
@@ -20,10 +19,3 @@ impl Exception {
         &self.what
     }
 }
-
-#[export_name = "cxxbridge03$exception"]
-unsafe extern "C" fn exception(ptr: *const u8, len: usize) -> *const u8 {
-    let slice = slice::from_raw_parts(ptr, len);
-    let boxed = String::from_utf8_lossy(slice).into_owned().into_boxed_str();
-    Box::leak(boxed).as_ptr()
-}
diff --git a/src/lib.rs b/src/lib.rs
index 37fc5ef4..86318c88 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -363,9 +363,7 @@
 extern crate link_cplusplus;
 
 #[macro_use]
-mod assert;
-#[macro_use]
-mod concat;
+mod macros;
 
 mod cxx_string;
 mod cxx_vector;
@@ -380,6 +378,9 @@ mod rust_vec;
 mod unique_ptr;
 mod unwind;
 
+#[cfg(not(no_export_symbols))]
+mod symbols;
+
 pub use crate::cxx_string::CxxString;
 pub use crate::cxx_vector::CxxVector;
 pub use crate::exception::Exception;
diff --git a/src/assert.rs b/src/macros/assert.rs
index 738e5bbd..738e5bbd 100644
--- a/src/assert.rs
+++ b/src/macros/assert.rs
diff --git a/src/concat.rs b/src/macros/concat.rs
index e67e50d4..e67e50d4 100644
--- a/src/concat.rs
+++ b/src/macros/concat.rs
diff --git a/src/macros/mod.rs b/src/macros/mod.rs
new file mode 100644
index 00000000..d12d96bd
--- /dev/null
+++ b/src/macros/mod.rs
@@ -0,0 +1,4 @@
+#[macro_use]
+mod assert;
+#[macro_use]
+mod concat;
diff --git a/src/rust_str.rs b/src/rust_str.rs
index fe114735..b944ede9 100644
--- a/src/rust_str.rs
+++ b/src/rust_str.rs
@@ -25,10 +25,4 @@ impl RustStr {
     }
 }
 
-#[export_name = "cxxbridge03$str$valid"]
-unsafe extern "C" fn str_valid(ptr: *const u8, len: usize) -> bool {
-    let slice = slice::from_raw_parts(ptr, len);
-    str::from_utf8(slice).is_ok()
-}
-
 const_assert_eq!(mem::size_of::<Option<RustStr>>(), mem::size_of::<RustStr>());
diff --git a/src/rust_string.rs b/src/rust_string.rs
index 6f3e64bd..a923ced9 100644
--- a/src/rust_string.rs
+++ b/src/rust_string.rs
@@ -1,7 +1,4 @@
-use std::mem::{self, ManuallyDrop, MaybeUninit};
-use std::ptr;
-use std::slice;
-use std::str;
+use std::mem;
 
 #[repr(C)]
 pub struct RustString {
@@ -30,46 +27,5 @@ impl RustString {
     }
 }
 
-#[export_name = "cxxbridge03$string$new"]
-unsafe extern "C" fn string_new(this: &mut MaybeUninit<String>) {
-    ptr::write(this.as_mut_ptr(), String::new());
-}
-
-#[export_name = "cxxbridge03$string$clone"]
-unsafe extern "C" fn string_clone(this: &mut MaybeUninit<String>, other: &String) {
-    ptr::write(this.as_mut_ptr(), other.clone());
-}
-
-#[export_name = "cxxbridge03$string$from"]
-unsafe extern "C" fn string_from(
-    this: &mut MaybeUninit<String>,
-    ptr: *const u8,
-    len: usize,
-) -> bool {
-    let slice = slice::from_raw_parts(ptr, len);
-    match str::from_utf8(slice) {
-        Ok(s) => {
-            ptr::write(this.as_mut_ptr(), s.to_owned());
-            true
-        }
-        Err(_) => false,
-    }
-}
-
-#[export_name = "cxxbridge03$string$drop"]
-unsafe extern "C" fn string_drop(this: &mut ManuallyDrop<String>) {
-    ManuallyDrop::drop(this);
-}
-
-#[export_name = "cxxbridge03$string$ptr"]
-unsafe extern "C" fn string_ptr(this: &String) -> *const u8 {
-    this.as_ptr()
-}
-
-#[export_name = "cxxbridge03$string$len"]
-unsafe extern "C" fn string_len(this: &String) -> usize {
-    this.len()
-}
-
 const_assert_eq!(mem::size_of::<[usize; 3]>(), mem::size_of::<String>());
 const_assert_eq!(mem::align_of::<usize>(), mem::align_of::<String>());
diff --git a/src/rust_vec.rs b/src/rust_vec.rs
index c17310d9..4c5035d6 100644
--- a/src/rust_vec.rs
+++ b/src/rust_vec.rs
@@ -1,6 +1,3 @@
-use std::mem;
-use std::ptr;
-
 #[repr(C)]
 pub struct RustVec<T> {
     repr: Vec<T>,
@@ -39,54 +36,3 @@ impl<T> RustVec<T> {
         self.repr.as_ptr()
     }
 }
-
-macro_rules! rust_vec_shims_for_primitive {
-    ($ty:ident) => {
-        const_assert_eq!(mem::size_of::<[usize; 3]>(), mem::size_of::<Vec<$ty>>());
-        const_assert_eq!(mem::align_of::<usize>(), mem::align_of::<Vec<$ty>>());
-
-        const _: () = {
-            attr! {
-                #[export_name = concat!("cxxbridge03$rust_vec$", stringify!($ty), "$new")]
-                unsafe extern "C" fn __new(this: *mut RustVec<$ty>) {
-                    ptr::write(this, RustVec::new());
-                }
-            }
-            attr! {
-                #[export_name = concat!("cxxbridge03$rust_vec$", stringify!($ty), "$drop")]
-                unsafe extern "C" fn __drop(this: *mut RustVec<$ty>) {
-                    ptr::drop_in_place(this);
-                }
-            }
-            attr! {
-                #[export_name = concat!("cxxbridge03$rust_vec$", stringify!($ty), "$len")]
-                unsafe extern "C" fn __len(this: *const RustVec<$ty>) -> usize {
-                    (*this).len()
-                }
-            }
-            attr! {
-                #[export_name = concat!("cxxbridge03$rust_vec$", stringify!($ty), "$data")]
-                unsafe extern "C" fn __data(this: *const RustVec<$ty>) -> *const $ty {
-                    (*this).as_ptr()
-                }
-            }
-            attr! {
-                #[export_name = concat!("cxxbridge03$rust_vec$", stringify!($ty), "$stride")]
-                unsafe extern "C" fn __stride() -> usize {
-                    mem::size_of::<$ty>()
-                }
-            }
-        };
-    };
-}
-
-rust_vec_shims_for_primitive!(u8);
-rust_vec_shims_for_primitive!(u16);
-rust_vec_shims_for_primitive!(u32);
-rust_vec_shims_for_primitive!(u64);
-rust_vec_shims_for_primitive!(i8);
-rust_vec_shims_for_primitive!(i16);
-rust_vec_shims_for_primitive!(i32);
-rust_vec_shims_for_primitive!(i64);
-rust_vec_shims_for_primitive!(f32);
-rust_vec_shims_for_primitive!(f64);
diff --git a/src/symbols/exception.rs b/src/symbols/exception.rs
new file mode 100644
index 00000000..849db3bc
--- /dev/null
+++ b/src/symbols/exception.rs
@@ -0,0 +1,8 @@
+use std::slice;
+
+#[export_name = "cxxbridge03$exception"]
+unsafe extern "C" fn exception(ptr: *const u8, len: usize) -> *const u8 {
+    let slice = slice::from_raw_parts(ptr, len);
+    let boxed = String::from_utf8_lossy(slice).into_owned().into_boxed_str();
+    Box::leak(boxed).as_ptr()
+}
diff --git a/src/symbols/lib.rs b/src/symbols/lib.rs
new file mode 100644
index 00000000..2c052ecf
--- /dev/null
+++ b/src/symbols/lib.rs
@@ -0,0 +1,5 @@
+#[path = "../macros/mod.rs"]
+#[macro_use]
+mod macros;
+
+include!("mod.rs");
diff --git a/src/symbols/mod.rs b/src/symbols/mod.rs
new file mode 100644
index 00000000..a9d158db
--- /dev/null
+++ b/src/symbols/mod.rs
@@ -0,0 +1,4 @@
+mod exception;
+mod rust_str;
+mod rust_string;
+mod rust_vec;
diff --git a/src/symbols/rust_str.rs b/src/symbols/rust_str.rs
new file mode 100644
index 00000000..6dc04acd
--- /dev/null
+++ b/src/symbols/rust_str.rs
@@ -0,0 +1,8 @@
+use std::slice;
+use std::str;
+
+#[export_name = "cxxbridge03$str$valid"]
+unsafe extern "C" fn str_valid(ptr: *const u8, len: usize) -> bool {
+    let slice = slice::from_raw_parts(ptr, len);
+    str::from_utf8(slice).is_ok()
+}
diff --git a/src/symbols/rust_string.rs b/src/symbols/rust_string.rs
new file mode 100644
index 00000000..63d4ba76
--- /dev/null
+++ b/src/symbols/rust_string.rs
@@ -0,0 +1,45 @@
+use std::mem::{ManuallyDrop, MaybeUninit};
+use std::ptr;
+use std::slice;
+use std::str;
+
+#[export_name = "cxxbridge03$string$new"]
+unsafe extern "C" fn string_new(this: &mut MaybeUninit<String>) {
+    ptr::write(this.as_mut_ptr(), String::new());
+}
+
+#[export_name = "cxxbridge03$string$clone"]
+unsafe extern "C" fn string_clone(this: &mut MaybeUninit<String>, other: &String) {
+    ptr::write(this.as_mut_ptr(), other.clone());
+}
+
+#[export_name = "cxxbridge03$string$from"]
+unsafe extern "C" fn string_from(
+    this: &mut MaybeUninit<String>,
+    ptr: *const u8,
+    len: usize,
+) -> bool {
+    let slice = slice::from_raw_parts(ptr, len);
+    match str::from_utf8(slice) {
+        Ok(s) => {
+            ptr::write(this.as_mut_ptr(), s.to_owned());
+            true
+        }
+        Err(_) => false,
+    }
+}
+
+#[export_name = "cxxbridge03$string$drop"]
+unsafe extern "C" fn string_drop(this: &mut ManuallyDrop<String>) {
+    ManuallyDrop::drop(this);
+}
+
+#[export_name = "cxxbridge03$string$ptr"]
+unsafe extern "C" fn string_ptr(this: &String) -> *const u8 {
+    this.as_ptr()
+}
+
+#[export_name = "cxxbridge03$string$len"]
+unsafe extern "C" fn string_len(this: &String) -> usize {
+    this.len()
+}
diff --git a/src/symbols/rust_vec.rs b/src/symbols/rust_vec.rs
new file mode 100644
index 00000000..712a9e8c
--- /dev/null
+++ b/src/symbols/rust_vec.rs
@@ -0,0 +1,65 @@
+use std::mem;
+use std::ptr;
+
+#[repr(C)]
+pub struct RustVec<T> {
+    repr: Vec<T>,
+}
+
+macro_rules! attr {
+    (#[$name:ident = $value:expr] $($rest:tt)*) => {
+        #[$name = $value]
+        $($rest)*
+    };
+}
+
+macro_rules! rust_vec_shims_for_primitive {
+    ($ty:ident) => {
+        const_assert_eq!(mem::size_of::<[usize; 3]>(), mem::size_of::<Vec<$ty>>());
+        const_assert_eq!(mem::align_of::<usize>(), mem::align_of::<Vec<$ty>>());
+
+        const _: () = {
+            attr! {
+                #[export_name = concat!("cxxbridge03$rust_vec$", stringify!($ty), "$new")]
+                unsafe extern "C" fn __new(this: *mut RustVec<$ty>) {
+                    ptr::write(this, RustVec { repr: Vec::new() });
+                }
+            }
+            attr! {
+                #[export_name = concat!("cxxbridge03$rust_vec$", stringify!($ty), "$drop")]
+                unsafe extern "C" fn __drop(this: *mut RustVec<$ty>) {
+                    ptr::drop_in_place(this);
+                }
+            }
+            attr! {
+                #[export_name = concat!("cxxbridge03$rust_vec$", stringify!($ty), "$len")]
+                unsafe extern "C" fn __len(this: *const RustVec<$ty>) -> usize {
+                    (*this).repr.len()
+                }
+            }
+            attr! {
+                #[export_name = concat!("cxxbridge03$rust_vec$", stringify!($ty), "$data")]
+                unsafe extern "C" fn __data(this: *const RustVec<$ty>) -> *const $ty {
+                    (*this).repr.as_ptr()
+                }
+            }
+            attr! {
+                #[export_name = concat!("cxxbridge03$rust_vec$", stringify!($ty), "$stride")]
+                unsafe extern "C" fn __stride() -> usize {
+                    mem::size_of::<$ty>()
+                }
+            }
+        };
+    };
+}
+
+rust_vec_shims_for_primitive!(u8);
+rust_vec_shims_for_primitive!(u16);
+rust_vec_shims_for_primitive!(u32);
+rust_vec_shims_for_primitive!(u64);
+rust_vec_shims_for_primitive!(i8);
+rust_vec_shims_for_primitive!(i16);
+rust_vec_shims_for_primitive!(i32);
+rust_vec_shims_for_primitive!(i64);
+rust_vec_shims_for_primitive!(f32);
+rust_vec_shims_for_primitive!(f64);