From 0e032955fbea5be39491fa796da1590a32a9c205 Mon Sep 17 00:00:00 2001
From: Alex Crichton <alex@alexcrichton.com>
Date: Mon, 16 Apr 2018 13:49:47 -0700
Subject: [PATCH] Use a `length` accessor instead of `byteLength`

This way we should be naturally compatible with normal JS arrays that get passed
in as well!

Closes #133
---
 crates/cli-support/src/js/mod.rs | 10 +++----
 tests/all/slice.rs               | 50 ++++++++++++++++++++++++++++++++
 2 files changed, 55 insertions(+), 5 deletions(-)

diff --git a/crates/cli-support/src/js/mod.rs b/crates/cli-support/src/js/mod.rs
index 704892e6d..a8fcbc6c3 100644
--- a/crates/cli-support/src/js/mod.rs
+++ b/crates/cli-support/src/js/mod.rs
@@ -672,7 +672,7 @@ impl<'a> Context<'a> {
         self.expose_uint8_memory();
         self.global(&format!("
             function passArray8ToWasm(arg) {{
-                const ptr = wasm.__wbindgen_malloc(arg.byteLength);
+                const ptr = wasm.__wbindgen_malloc(arg.length);
                 getUint8Memory().set(arg, ptr);
                 return [ptr, arg.length];
             }}
@@ -687,7 +687,7 @@ impl<'a> Context<'a> {
         self.expose_uint16_memory();
         self.global(&format!("
             function passArray16ToWasm(arg) {{
-                const ptr = wasm.__wbindgen_malloc(arg.byteLength);
+                const ptr = wasm.__wbindgen_malloc(arg.length * 2);
                 getUint16Memory().set(arg, ptr / 2);
                 return [ptr, arg.length];
             }}
@@ -702,7 +702,7 @@ impl<'a> Context<'a> {
         self.expose_uint32_memory();
         self.global(&format!("
             function passArray32ToWasm(arg) {{
-                const ptr = wasm.__wbindgen_malloc(arg.byteLength);
+                const ptr = wasm.__wbindgen_malloc(arg.length * 4);
                 getUint32Memory().set(arg, ptr / 4);
                 return [ptr, arg.length];
             }}
@@ -716,7 +716,7 @@ impl<'a> Context<'a> {
         self.required_internal_exports.insert("__wbindgen_malloc");
         self.global(&format!("
             function passArrayF32ToWasm(arg) {{
-                const ptr = wasm.__wbindgen_malloc(arg.byteLength);
+                const ptr = wasm.__wbindgen_malloc(arg.length * 4);
                 new Float32Array(wasm.memory.buffer).set(arg, ptr / 4);
                 return [ptr, arg.length];
             }}
@@ -730,7 +730,7 @@ impl<'a> Context<'a> {
         self.required_internal_exports.insert("__wbindgen_malloc");
         self.global(&format!("
             function passArrayF64ToWasm(arg) {{
-                const ptr = wasm.__wbindgen_malloc(arg.byteLength);
+                const ptr = wasm.__wbindgen_malloc(arg.length * 8);
                 new Float64Array(wasm.memory.buffer).set(arg, ptr / 8);
                 return [ptr, arg.length];
             }}
diff --git a/tests/all/slice.rs b/tests/all/slice.rs
index daba1f9fb..f3bfab675 100644
--- a/tests/all/slice.rs
+++ b/tests/all/slice.rs
@@ -228,3 +228,53 @@ fn import() {
         "#)
         .test();
 }
+
+#[test]
+fn pass_array_works() {
+    project()
+        .file("src/lib.rs", r#"
+            #![feature(proc_macro, wasm_custom_section, wasm_import_module)]
+
+            extern crate wasm_bindgen;
+
+            use wasm_bindgen::prelude::*;
+
+            macro_rules! doit {
+                ($(($rust:ident, $i:ident))*) => ($(
+                    #[wasm_bindgen]
+                    pub fn $rust(a: &[$i]) {
+                        assert_eq!(a.len(), 2);
+                        assert_eq!(a[0], 1 as $i);
+                        assert_eq!(a[1], 2 as $i);
+                    }
+                )*)
+            }
+
+
+            doit! {
+                (rust_i8, i8)
+                (rust_u8, u8)
+                (rust_i16, i16)
+                (rust_u16, u16)
+                (rust_i32, i32)
+                (rust_u32, u32)
+                (rust_f32, f32)
+                (rust_f64, f64)
+            }
+        "#)
+        .file("test.js", r#"
+            const wasm = require("./out");
+
+            module.exports.test = function() {
+                wasm.rust_i8([1, 2]);
+                wasm.rust_u8([1, 2]);
+                wasm.rust_i16([1, 2]);
+                wasm.rust_u16([1, 2]);
+                wasm.rust_i32([1, 2]);
+                wasm.rust_u32([1, 2]);
+                wasm.rust_f32([1, 2]);
+                wasm.rust_f64([1, 2]);
+            };
+        "#)
+        .test();
+}