From 8058701f7e195636fd1759f10187fa431b7aa61c Mon Sep 17 00:00:00 2001
From: Alan Somers <asomers@gmail.com>
Date: Thu, 4 Jul 2019 13:02:02 -0600
Subject: [PATCH] Fix mocking methods with mutable arguments

---
 mockall_derive/src/automock.rs | 44 ++++++++++++++++++++++++++++++----
 mockall_derive/src/mock.rs     |  2 +-
 2 files changed, 41 insertions(+), 5 deletions(-)

diff --git a/mockall_derive/src/automock.rs b/mockall_derive/src/automock.rs
index e2b5e965..1da0238b 100644
--- a/mockall_derive/src/automock.rs
+++ b/mockall_derive/src/automock.rs
@@ -345,7 +345,7 @@ fn mock_function(vis: &syn::Visibility,
 {
     let fn_token = &decl.fn_token;
     let generics = &decl.generics;
-    let inputs = &decl.inputs;
+    let inputs = demutify(&decl.inputs);
     let output = match &decl.output{
         syn::ReturnType::Default => quote!(-> ()),
         _ => {
@@ -361,7 +361,7 @@ fn mock_function(vis: &syn::Visibility,
         return TokenStream::new();
     }
 
-    for p in decl.inputs.iter() {
+    for p in inputs.iter() {
         match p {
             syn::FnArg::Captured(arg) => {
                 args.push(arg.pat.clone());
@@ -878,6 +878,42 @@ mod t {
         check(&attrs, &desired, &code);
     }
 
+    #[test]
+    fn foreign_mutable_arg() {
+        let attrs = "mod mock;";
+        let desired = r#"
+        pub mod mock {
+            ::mockall::expectation!{
+                pub(in super::super) fn __foo< >(x: u32) -> i64 {
+                    let (p0: &u32) = (&x);
+                }
+            }
+            ::mockall::lazy_static!{
+                static ref foo_expectation:
+                    ::std::sync::Mutex< __foo::Expectations>
+                    = ::std::sync::Mutex::new(__foo::Expectations:: < > ::new());
+            }
+            pub(in super) unsafe fn foo(x: u32) -> i64 {
+                foo_expectation.lock().unwrap().call(x)
+            }
+            pub(in super) fn expect_foo< 'guard>()
+                -> __foo::ExpectationGuard< 'guard, >
+            {
+                __foo::ExpectationGuard:: < > ::new(foo_expectation.lock().unwrap())
+            }
+            pub fn checkpoint() {
+                foo_expectation.lock().unwrap().checkpoint();
+            }
+        }
+        "#;
+        let code = r#"
+        extern "Rust" {
+            fn foo(mut x: u32) -> i64;
+        }
+        "#;
+        check(&attrs, &desired, &code);
+    }
+
     #[test]
     fn generic_method() {
         check("",
@@ -1589,12 +1625,12 @@ mod t {
         pub mod __mock_Foo {
             use super:: * ;
             ::mockall::expectation!{
-                pub fn foo< >(&self, mut x: u32) -> () {
+                pub fn foo< >(&self, x: u32) -> () {
                     let (p1: &u32) = (&x);
                 }
             }
             ::mockall::expectation!{
-                pub fn bar< >(mut self) -> () { let () = (); }
+                pub fn bar< >(self) -> () { let () = (); }
             }
         }
         pub struct MockFoo {
diff --git a/mockall_derive/src/mock.rs b/mockall_derive/src/mock.rs
index ce537d2a..583df892 100644
--- a/mockall_derive/src/mock.rs
+++ b/mockall_derive/src/mock.rs
@@ -363,7 +363,7 @@ fn gen_struct<T>(mock_ident: &syn::Ident,
         let attrs = format_attrs(&meth.borrow().attrs);
         let method_ident = &meth.borrow().sig.ident;
         let meth_types = method_types(&meth.borrow().sig, Some(generics));
-        let args = &meth.borrow().sig.decl.inputs;
+        let args = demutify(&meth.borrow().sig.decl.inputs);
         let expect_obj = &meth_types.expect_obj;
         let expectations = &meth_types.expectations;
         let altargs = &meth_types.altargs;