Update clippy

Author: Manishearth

.travis.yml

@@ -1,5 +1,5 @@
 dist: xenial
-language: minimal
+language: bash
 
 os:
   - linux

CHANGELOG.md

@@ -1033,6 +1033,7 @@ Released 2018-09-13
 [`inconsistent_digit_grouping`]: https://rust-lang.github.io/rust-clippy/master/index.html#inconsistent_digit_grouping
 [`indexing_slicing`]: https://rust-lang.github.io/rust-clippy/master/index.html#indexing_slicing
 [`ineffective_bit_mask`]: https://rust-lang.github.io/rust-clippy/master/index.html#ineffective_bit_mask
+[`inefficient_to_string`]: https://rust-lang.github.io/rust-clippy/master/index.html#inefficient_to_string
 [`infallible_destructuring_match`]: https://rust-lang.github.io/rust-clippy/master/index.html#infallible_destructuring_match
 [`infinite_iter`]: https://rust-lang.github.io/rust-clippy/master/index.html#infinite_iter
 [`inherent_to_string`]: https://rust-lang.github.io/rust-clippy/master/index.html#inherent_to_string
@@ -1128,6 +1129,7 @@ Released 2018-09-13
 [`ok_expect`]: https://rust-lang.github.io/rust-clippy/master/index.html#ok_expect
 [`op_ref`]: https://rust-lang.github.io/rust-clippy/master/index.html#op_ref
 [`option_and_then_some`]: https://rust-lang.github.io/rust-clippy/master/index.html#option_and_then_some
+[`option_expect_used`]: https://rust-lang.github.io/rust-clippy/master/index.html#option_expect_used
 [`option_map_or_none`]: https://rust-lang.github.io/rust-clippy/master/index.html#option_map_or_none
 [`option_map_unit_fn`]: https://rust-lang.github.io/rust-clippy/master/index.html#option_map_unit_fn
 [`option_map_unwrap_or`]: https://rust-lang.github.io/rust-clippy/master/index.html#option_map_unwrap_or
@@ -1137,6 +1139,7 @@ Released 2018-09-13
 [`or_fun_call`]: https://rust-lang.github.io/rust-clippy/master/index.html#or_fun_call
 [`out_of_bounds_indexing`]: https://rust-lang.github.io/rust-clippy/master/index.html#out_of_bounds_indexing
 [`overflow_check_conditional`]: https://rust-lang.github.io/rust-clippy/master/index.html#overflow_check_conditional
+[`panic`]: https://rust-lang.github.io/rust-clippy/master/index.html#panic
 [`panic_params`]: https://rust-lang.github.io/rust-clippy/master/index.html#panic_params
 [`panicking_unwrap`]: https://rust-lang.github.io/rust-clippy/master/index.html#panicking_unwrap
 [`partialeq_ne_impl`]: https://rust-lang.github.io/rust-clippy/master/index.html#partialeq_ne_impl
@@ -1166,6 +1169,7 @@ Released 2018-09-13
 [`ref_in_deref`]: https://rust-lang.github.io/rust-clippy/master/index.html#ref_in_deref
 [`regex_macro`]: https://rust-lang.github.io/rust-clippy/master/index.html#regex_macro
 [`replace_consts`]: https://rust-lang.github.io/rust-clippy/master/index.html#replace_consts
+[`result_expect_used`]: https://rust-lang.github.io/rust-clippy/master/index.html#result_expect_used
 [`result_map_unit_fn`]: https://rust-lang.github.io/rust-clippy/master/index.html#result_map_unit_fn
 [`result_map_unwrap_or_else`]: https://rust-lang.github.io/rust-clippy/master/index.html#result_map_unwrap_or_else
 [`result_unwrap_used`]: https://rust-lang.github.io/rust-clippy/master/index.html#result_unwrap_used
@@ -1197,6 +1201,7 @@ Released 2018-09-13
 [`suspicious_unary_op_formatting`]: https://rust-lang.github.io/rust-clippy/master/index.html#suspicious_unary_op_formatting
 [`temporary_assignment`]: https://rust-lang.github.io/rust-clippy/master/index.html#temporary_assignment
 [`temporary_cstring_as_ptr`]: https://rust-lang.github.io/rust-clippy/master/index.html#temporary_cstring_as_ptr
+[`todo`]: https://rust-lang.github.io/rust-clippy/master/index.html#todo
 [`too_many_arguments`]: https://rust-lang.github.io/rust-clippy/master/index.html#too_many_arguments
 [`too_many_lines`]: https://rust-lang.github.io/rust-clippy/master/index.html#too_many_lines
 [`toplevel_ref_arg`]: https://rust-lang.github.io/rust-clippy/master/index.html#toplevel_ref_arg
@@ -1226,6 +1231,7 @@ Released 2018-09-13
 [`unnecessary_unwrap`]: https://rust-lang.github.io/rust-clippy/master/index.html#unnecessary_unwrap
 [`unneeded_field_pattern`]: https://rust-lang.github.io/rust-clippy/master/index.html#unneeded_field_pattern
 [`unneeded_wildcard_pattern`]: https://rust-lang.github.io/rust-clippy/master/index.html#unneeded_wildcard_pattern
+[`unreachable`]: https://rust-lang.github.io/rust-clippy/master/index.html#unreachable
 [`unreadable_literal`]: https://rust-lang.github.io/rust-clippy/master/index.html#unreadable_literal
 [`unsafe_removed_from_name`]: https://rust-lang.github.io/rust-clippy/master/index.html#unsafe_removed_from_name
 [`unsafe_vector_initialization`]: https://rust-lang.github.io/rust-clippy/master/index.html#unsafe_vector_initialization

README.md

@@ -6,7 +6,7 @@
 
 A collection of lints to catch common mistakes and improve your [Rust](https://github.com/rust-lang/rust) code.
 
-[There are 325 lints included in this crate!](https://rust-lang.github.io/rust-clippy/master/index.html)
+[There are 331 lints included in this crate!](https://rust-lang.github.io/rust-clippy/master/index.html)
 
 We have a bunch of lint categories to allow you to choose how much Clippy is supposed to ~~annoy~~ help you:
 

appveyor.yml

@@ -15,7 +15,7 @@ branches:
 
 cache:
     - '%USERPROFILE%\.cargo'
-on_finish:
+after_test:
     - cargo install -Z install-upgrade cargo-cache --debug
     - cargo cache --autoclean
 
@@ -24,7 +24,7 @@ install:
     - rustup-init.exe -y --default-host %TARGET% --default-toolchain nightly --profile=minimal
     - set PATH=%PATH%;C:\Users\appveyor\.cargo\bin
     - del rust-toolchain
-    - cargo install -Z install-upgrade rustup-toolchain-install-master --debug || echo "rustup-toolchain-install-master already installed"
+    - cargo install -Z install-upgrade rustup-toolchain-install-master
     - rustup-toolchain-install-master -f -n master
     - rustup component add rustfmt --toolchain nightly & exit 0 # Format test handles missing rustfmt
     - rustup default master

clippy_lints/src/functions.rs

@@ -1,6 +1,6 @@
 use crate::utils::{
-    iter_input_pats, match_def_path, qpath_res, return_ty, snippet, snippet_opt, span_help_and_lint, span_lint,
-    span_lint_and_then, type_is_unsafe_function,
+    attrs::is_proc_macro, iter_input_pats, match_def_path, qpath_res, return_ty, snippet, snippet_opt,
+    span_help_and_lint, span_lint, span_lint_and_then, type_is_unsafe_function,
 };
 use matches::matches;
 use rustc::hir::{self, def::Res, def_id::DefId, intravisit};
@@ -234,7 +234,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Functions {
                 check_needless_must_use(cx, decl, item.hir_id, item.span, fn_header_span, attr);
                 return;
             }
-            if cx.access_levels.is_exported(item.hir_id) {
+            if cx.access_levels.is_exported(item.hir_id) && !is_proc_macro(&item.attrs) {
                 check_must_use_candidate(
                     cx,
                     decl,
@@ -254,7 +254,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Functions {
             if let Some(attr) = attr {
                 let fn_header_span = item.span.with_hi(sig.decl.output.span().hi());
                 check_needless_must_use(cx, &sig.decl, item.hir_id, item.span, fn_header_span, attr);
-            } else if cx.access_levels.is_exported(item.hir_id) {
+            } else if cx.access_levels.is_exported(item.hir_id) && !is_proc_macro(&item.attrs) {
                 check_must_use_candidate(
                     cx,
                     &sig.decl,
@@ -284,7 +284,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Functions {
                 let body = cx.tcx.hir().body(eid);
                 Self::check_raw_ptr(cx, sig.header.unsafety, &sig.decl, body, item.hir_id);
 
-                if attr.is_none() && cx.access_levels.is_exported(item.hir_id) {
+                if attr.is_none() && cx.access_levels.is_exported(item.hir_id) && !is_proc_macro(&item.attrs) {
                     check_must_use_candidate(
                         cx,
                         &sig.decl,
@@ -493,7 +493,7 @@ fn is_must_use_ty<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, ty: Ty<'tcx>) -> bool {
         },
         Tuple(ref substs) => substs.types().any(|ty| is_must_use_ty(cx, ty)),
         Opaque(ref def_id, _) => {
-            for (predicate, _) in &cx.tcx.predicates_of(*def_id).predicates {
+            for (predicate, _) in cx.tcx.predicates_of(*def_id).predicates {
                 if let ty::Predicate::Trait(ref poly_trait_predicate) = predicate {
                     if must_use_attr(&cx.tcx.get_attrs(poly_trait_predicate.skip_binder().trait_ref.def_id)).is_some() {
                         return true;

clippy_lints/src/lib.rs

@@ -625,13 +625,18 @@ pub fn register_plugins(reg: &mut rustc_driver::plugin::Registry<'_>, conf: &Con
         mem_forget::MEM_FORGET,
         methods::CLONE_ON_REF_PTR,
         methods::GET_UNWRAP,
+        methods::OPTION_EXPECT_USED,
         methods::OPTION_UNWRAP_USED,
+        methods::RESULT_EXPECT_USED,
         methods::RESULT_UNWRAP_USED,
         methods::WRONG_PUB_SELF_CONVENTION,
         misc::FLOAT_CMP_CONST,
         missing_doc::MISSING_DOCS_IN_PRIVATE_ITEMS,
         missing_inline::MISSING_INLINE_IN_PUBLIC_ITEMS,
+        panic_unimplemented::PANIC,
+        panic_unimplemented::TODO,
         panic_unimplemented::UNIMPLEMENTED,
+        panic_unimplemented::UNREACHABLE,
         shadow::SHADOW_REUSE,
         shadow::SHADOW_SAME,
         strings::STRING_ADD,
@@ -808,6 +813,7 @@ pub fn register_plugins(reg: &mut rustc_driver::plugin::Registry<'_>, conf: &Con
         methods::EXPECT_FUN_CALL,
         methods::FILTER_NEXT,
         methods::FLAT_MAP_IDENTITY,
+        methods::INEFFICIENT_TO_STRING,
         methods::INTO_ITER_ON_ARRAY,
         methods::INTO_ITER_ON_REF,
         methods::ITER_CLONED_COLLECT,
@@ -1184,6 +1190,7 @@ pub fn register_plugins(reg: &mut rustc_driver::plugin::Registry<'_>, conf: &Con
         loops::MANUAL_MEMCPY,
         loops::NEEDLESS_COLLECT,
         methods::EXPECT_FUN_CALL,
+        methods::INEFFICIENT_TO_STRING,
         methods::ITER_NTH,
         methods::OR_FUN_CALL,
         methods::SINGLE_CHAR_PATTERN,

clippy_lints/src/methods/inefficient_to_string.rs

@@ -0,0 +1,55 @@
+use super::INEFFICIENT_TO_STRING;
+use crate::utils::{match_def_path, paths, snippet_with_applicability, span_lint_and_then, walk_ptrs_ty_depth};
+use if_chain::if_chain;
+use rustc::hir;
+use rustc::lint::LateContext;
+use rustc::ty::{self, Ty};
+use rustc_errors::Applicability;
+
+/// Checks for the `INEFFICIENT_TO_STRING` lint
+pub fn lint<'tcx>(cx: &LateContext<'_, 'tcx>, expr: &hir::Expr, arg: &hir::Expr, arg_ty: Ty<'tcx>) {
+    if_chain! {
+        if let Some(to_string_meth_did) = cx.tables.type_dependent_def_id(expr.hir_id);
+        if match_def_path(cx, to_string_meth_did, &paths::TO_STRING_METHOD);
+        if let Some(substs) = cx.tables.node_substs_opt(expr.hir_id);
+        let self_ty = substs.type_at(0);
+        let (deref_self_ty, deref_count) = walk_ptrs_ty_depth(self_ty);
+        if deref_count >= 1;
+        if specializes_tostring(cx, deref_self_ty);
+        then {
+            span_lint_and_then(
+                cx,
+                INEFFICIENT_TO_STRING,
+                expr.span,
+                &format!("calling `to_string` on `{}`", arg_ty),
+                |db| {
+                    db.help(&format!(
+                        "`{}` implements `ToString` through a slower blanket impl, but `{}` has a fast specialization of `ToString`",
+                        self_ty, deref_self_ty
+                    ));
+                    let mut applicability = Applicability::MachineApplicable;
+                    let arg_snippet = snippet_with_applicability(cx, arg.span, "..", &mut applicability);
+                    db.span_suggestion(
+                        expr.span,
+                        "try dereferencing the receiver",
+                        format!("({}{}).to_string()", "*".repeat(deref_count), arg_snippet),
+                        applicability,
+                    );
+                },
+            );
+        }
+    }
+}
+
+/// Returns whether `ty` specializes `ToString`.
+/// Currently, these are `str`, `String`, and `Cow<'_, str>`.
+fn specializes_tostring(cx: &LateContext<'_, '_>, ty: Ty<'_>) -> bool {
+    match ty.kind {
+        ty::Str => true,
+        ty::Adt(adt, substs) => {
+            match_def_path(cx, adt.did, &paths::STRING)
+                || (match_def_path(cx, adt.did, &paths::COW) && substs.type_at(1).is_str())
+        },
+        _ => false,
+    }
+}