From 749ac6502f6fda5af26715b9908e4ca079926b8c Mon Sep 17 00:00:00 2001
From: Robert Masen <r@robertmasen.pizza>
Date: Sun, 17 Jun 2018 20:13:56 -0500
Subject: [PATCH 1/2] add ptr validation

---
 crates/backend/src/ast.rs            | 1 +
 crates/cli-support/src/js/js2rust.rs | 8 +++++++-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/crates/backend/src/ast.rs b/crates/backend/src/ast.rs
index 8d1ac66c..9da6ed61 100644
--- a/crates/backend/src/ast.rs
+++ b/crates/backend/src/ast.rs
@@ -2,6 +2,7 @@ use proc_macro2::{Ident, Span, TokenStream, TokenTree};
 use quote::ToTokens;
 use shared;
 use syn;
+use syn::AttrStyle;
 
 #[cfg_attr(feature = "extra-traits", derive(Debug, PartialEq, Eq))]
 #[derive(Default)]
diff --git a/crates/cli-support/src/js/js2rust.rs b/crates/cli-support/src/js/js2rust.rs
index c0d45787..00c24fdf 100644
--- a/crates/cli-support/src/js/js2rust.rs
+++ b/crates/cli-support/src/js/js2rust.rs
@@ -68,6 +68,9 @@ impl<'a, 'b> Js2Rust<'a, 'b> {
     /// passed should be `this.ptr`.
     pub fn method(&mut self, method: bool) -> &mut Self {
         if method {
+            self.prelude("if (this.ptr === 0) {
+                throw new Error('Attempt to use a moved value');
+            }");
             self.rust_arguments.insert(0, "this.ptr".to_string());
         }
         self
@@ -149,6 +152,9 @@ impl<'a, 'b> Js2Rust<'a, 'b> {
             } else {
                 self.prelude(&format!("\
                     const ptr{i} = {arg}.ptr;\n\
+                    if (ptr{i} === 0) {{
+                        throw new Error('Attempt to use a moved value');
+                    }}
                     {arg}.ptr = 0;\n\
                 ", i = i, arg = name));
                 self.rust_arguments.push(format!("ptr{}", i));
@@ -361,4 +367,4 @@ impl<'a, 'b> Js2Rust<'a, 'b> {
         let ts = format!("{} {}({}): {};\n", prefix, self.js_name, ts_args, self.ret_ty);
         (js, ts)
     }
-}
+}
\ No newline at end of file

From e9ea2dabc10cbf2991768cb60895440ddad99543 Mon Sep 17 00:00:00 2001
From: Robert Masen <r@robertmasen.pizza>
Date: Mon, 18 Jun 2018 15:34:48 -0500
Subject: [PATCH 2/2] add Validate ptr test

---
 tests/all/main.rs         |  1 +
 tests/all/validate_prt.rs | 69 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 70 insertions(+)
 create mode 100644 tests/all/validate_prt.rs

diff --git a/tests/all/main.rs b/tests/all/main.rs
index b909788a..2e7eaad0 100644
--- a/tests/all/main.rs
+++ b/tests/all/main.rs
@@ -538,3 +538,4 @@ mod structural;
 mod u64;
 mod webidl;
 mod comments;
+mod validate_prt;
\ No newline at end of file
diff --git a/tests/all/validate_prt.rs b/tests/all/validate_prt.rs
new file mode 100644
index 00000000..53c59a65
--- /dev/null
+++ b/tests/all/validate_prt.rs
@@ -0,0 +1,69 @@
+use super::project;
+
+#[test]
+fn works() {
+    project()
+        .file("src/lib.rs", r#"
+            #![feature(proc_macro, wasm_custom_section, wasm_import_module)]
+            extern crate wasm_bindgen;
+            use wasm_bindgen::prelude::*;
+            #[wasm_bindgen]
+            pub struct Fruit {
+                name: String,
+            }
+            #[wasm_bindgen]
+            impl Fruit {
+                #[wasm_bindgen(method)]
+                pub fn name(&self) -> String {
+                    self.name.clone()
+                }
+                #[wasm_bindgen(constructor)]
+                pub fn new(name: String) -> Self {
+                    Fruit {
+                        name,
+                    }
+                }
+            }
+            #[wasm_bindgen]
+            pub fn eat(_fruit: Fruit) { }
+        "#)
+        .file("test.js", r#"
+            import * as wasm from './out';
+            const targetMessage = 'Attempt to use a moved value';
+            function assertEq(a, b) {
+                console.log(a, '?=', b);
+                if (a === b)
+                return;
+                throw new Error('not equal');
+            }
+            export function test() {
+                useMoved();
+                moveMoved();
+            }
+            export function useMoved() {
+                // create a new struct
+                let apple = new wasm.Fruit('apple');
+                // sanity check that this method works
+                let name = apple.name();
+                // consume the struct
+                wasm.eat(apple);
+                // try and use the moved apple again
+                try {
+                    let movedName = apple.name();
+                } catch (e) {
+                    assertEq(e.message, targetMessage);
+                }
+            }
+            export function moveMoved() {
+                let pear = new wasm.Fruit('pear');
+                let name = pear.name();
+                wasm.eat(pear);
+                try {
+                    wasm.eat(pear);
+                } catch (e) {
+                    assertEq(e.message, targetMessage);
+                }
+            }
+        "#)
+        .test();
+}