Integrate rustfix into Clippy test suite

CONTRIBUTING.md

@@ -156,6 +156,15 @@ Therefore you should use `tests/ui/update-all-references.sh` (after running
 `cargo test`) and check whether the output looks as you expect with `git diff`. Commit all
 `*.stderr` files, too.
 
+If the lint you are working on is making use of structured suggestions, the
+test file should include a `// run-rustfix` comment at the top. This will
+additionally run [rustfix](https://github.com/rust-lang-nursery/rustfix) for
+that test. Rustfix will apply the suggestions from the lint to the code of the
+test file and compare that to the contents of a `.fixed` file.
+
+Use `tests/ui/update-all-references.sh` to automatically generate the
+`.fixed` file after running `cargo test`.
+
 ### Running rustfmt
 
 [Rustfmt](https://github.com/rust-lang/rustfmt) is a tool for formatting Rust code according

Cargo.toml

@@ -48,7 +48,7 @@ rustc_tools_util = { version = "0.1.0", path = "rustc_tools_util"}
 [dev-dependencies]
 clippy_dev = { version = "0.0.1", path = "clippy_dev" }
 cargo_metadata = "0.6.2"
-compiletest_rs = "0.3.16"
+compiletest_rs = "0.3.18"
 lazy_static = "1.0"
 serde_derive = "1.0"
 clippy-mini-macro-test = { version = "0.2", path = "mini-macro" }

clippy_lints/src/reference.rs

@@ -98,7 +98,7 @@ impl LintPass for DerefPass {
 impl EarlyLintPass for DerefPass {
     fn check_expr(&mut self, cx: &EarlyContext<'_>, e: &Expr) {
         if_chain! {
-            if let ExprKind::Field(ref object, ref field_name) = e.node;
+            if let ExprKind::Field(ref object, _) = e.node;
             if let ExprKind::Paren(ref parened) = object.node;
             if let ExprKind::AddrOf(_, ref inner) = parened.node;
             then {
@@ -109,11 +109,7 @@ impl EarlyLintPass for DerefPass {
                     object.span,
                     "Creating a reference that is immediately dereferenced.",
                     "try this",
-                    format!(
-                        "{}.{}",
-                        snippet_with_applicability(cx, inner.span, "_", &mut applicability),
-                        snippet_with_applicability(cx, field_name.span, "_", &mut applicability)
-                    ),
+                    snippet_with_applicability(cx, inner.span, "_", &mut applicability).to_string(),
                     applicability,
                 );
             }

tests/ui/unnecessary_ref.fixed

@@ -0,0 +1,23 @@
+// Copyright 2014-2018 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// run-rustfix
+
+#![feature(stmt_expr_attributes)]
+#![allow(unused_variables)]
+
+struct Outer {
+    inner: u32,
+}
+
+#[deny(clippy::ref_in_deref)]
+fn main() {
+    let outer = Outer { inner: 0 };
+    let inner = outer.inner;
+}

tests/ui/unnecessary_ref.rs

@@ -7,8 +7,10 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(tool_attributes)]
+// run-rustfix
+
 #![feature(stmt_expr_attributes)]
+#![allow(unused_variables)]
 
 struct Outer {
     inner: u32,

tests/ui/unnecessary_ref.stderr

@@ -1,11 +1,11 @@
 error: Creating a reference that is immediately dereferenced.
-  --> $DIR/unnecessary_ref.rs:20:17
+  --> $DIR/unnecessary_ref.rs:22:17
    |
 LL |     let inner = (&outer).inner;
-   |                 ^^^^^^^^ help: try this: `outer.inner`
+   |                 ^^^^^^^^ help: try this: `outer`
    |
 note: lint level defined here
-  --> $DIR/unnecessary_ref.rs:17:8
+  --> $DIR/unnecessary_ref.rs:19:8
    |
 LL | #[deny(clippy::ref_in_deref)]
    |        ^^^^^^^^^^^^^^^^^^^^

tests/ui/update-references.sh

@@ -34,6 +34,7 @@ shift
 while [[ "$1" != "" ]]; do
     STDERR_NAME="${1/%.rs/.stderr}"
     STDOUT_NAME="${1/%.rs/.stdout}"
+    FIXED_NAME="${1/%.rs/.fixed}"
     shift
     if [ -f $BUILD_DIR/$STDOUT_NAME ] && \
            ! (diff $BUILD_DIR/$STDOUT_NAME $MYDIR/$STDOUT_NAME >& /dev/null); then
@@ -45,6 +46,11 @@ while [[ "$1" != "" ]]; do
         echo updating $MYDIR/$STDERR_NAME
         cp $BUILD_DIR/$STDERR_NAME $MYDIR/$STDERR_NAME
     fi
+    if [ -f $BUILD_DIR/$FIXED_NAME ] && \
+           ! (diff $BUILD_DIR/$FIXED_NAME $MYDIR/$FIXED_NAME >& /dev/null); then
+        echo updating $MYDIR/$FIXED_NAME
+        cp $BUILD_DIR/$FIXED_NAME $MYDIR/$FIXED_NAME
+    fi
 done