Merge branch 'master' into issue-4078

Author: EthanTheMaster

.github/PULL_REQUEST_TEMPLATE renamed to .github/PULL_REQUEST_TEMPLATE.md

@@ -1,4 +1,3 @@
-<!--
 Thank you for making Clippy better!
 
 We're collecting our changelog from pull request descriptions.
@@ -25,6 +24,8 @@ checked during review or continuous integration.
 Note that you can skip the above if you are just opening a WIP PR in
 order to get feedback.
 
-Delete this line and everything above before opening your PR -->
+Delete this line and everything above before opening your PR.
+
+---
 
 changelog: none

CHANGELOG.md

@@ -976,6 +976,7 @@ Released 2018-09-13
 [`diverging_sub_expression`]: https://rust-lang.github.io/rust-clippy/master/index.html#diverging_sub_expression
 [`doc_markdown`]: https://rust-lang.github.io/rust-clippy/master/index.html#doc_markdown
 [`double_comparisons`]: https://rust-lang.github.io/rust-clippy/master/index.html#double_comparisons
+[`double_must_use`]: https://rust-lang.github.io/rust-clippy/master/index.html#double_must_use
 [`double_neg`]: https://rust-lang.github.io/rust-clippy/master/index.html#double_neg
 [`double_parens`]: https://rust-lang.github.io/rust-clippy/master/index.html#double_parens
 [`drop_bounds`]: https://rust-lang.github.io/rust-clippy/master/index.html#drop_bounds
@@ -1095,6 +1096,8 @@ Released 2018-09-13
 [`modulo_one`]: https://rust-lang.github.io/rust-clippy/master/index.html#modulo_one
 [`multiple_crate_versions`]: https://rust-lang.github.io/rust-clippy/master/index.html#multiple_crate_versions
 [`multiple_inherent_impl`]: https://rust-lang.github.io/rust-clippy/master/index.html#multiple_inherent_impl
+[`must_use_candidate`]: https://rust-lang.github.io/rust-clippy/master/index.html#must_use_candidate
+[`must_use_unit`]: https://rust-lang.github.io/rust-clippy/master/index.html#must_use_unit
 [`mut_from_ref`]: https://rust-lang.github.io/rust-clippy/master/index.html#mut_from_ref
 [`mut_mut`]: https://rust-lang.github.io/rust-clippy/master/index.html#mut_mut
 [`mut_range_bound`]: https://rust-lang.github.io/rust-clippy/master/index.html#mut_range_bound

CONTRIBUTING.md

@@ -147,7 +147,7 @@ You can use [rustup-toolchain-install-master][rtim] to do that:
 
 ```bash
 cargo install rustup-toolchain-install-master
-rustup-toolchain-install-master -n master --force
+rustup-toolchain-install-master --force -n master
 rustup override set master
 cargo test
 ```

Cargo.toml

@@ -46,7 +46,7 @@ rustc_tools_util = { version = "0.2.0", path = "rustc_tools_util"}
 
 [dev-dependencies]
 cargo_metadata = "0.8.0"
-compiletest_rs = { version = "0.3.23", features = ["tmp"] }
+compiletest_rs = { version = "0.3.24", features = ["tmp"] }
 lazy_static = "1.0"
 clippy-mini-macro-test = { version = "0.2", path = "mini-macro" }
 serde = { version = "1.0", features = ["derive"] }

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 322 lints included in this crate!](https://rust-lang.github.io/rust-clippy/master/index.html)
+[There are 324 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

@@ -17,11 +17,9 @@ install:
     - curl -sSf -o rustup-init.exe https://win.rustup.rs/
     - rustup-init.exe -y --default-host %TARGET% --default-toolchain nightly
     - set PATH=%PATH%;C:\Users\appveyor\.cargo\bin
-    - git ls-remote https://github.com/rust-lang/rust.git master | awk '{print $1}' >rustc-hash.txt
-    - set /p RUSTC_HASH=<rustc-hash.txt
     - del rust-toolchain
-    - cargo install rustup-toolchain-install-master --debug || echo "rustup-toolchain-install-master already installed"
-    - rustup-toolchain-install-master %RUSTC_HASH% -f -n master
+    - cargo install --git https://github.com/kennytm/rustup-toolchain-install-master --debug || echo "rustup-toolchain-install-master already installed"
+    - rustup-toolchain-install-master -f -n master
     - rustup component add rustfmt --toolchain nightly & exit 0 # Format test handles missing rustfmt
     - rustup default master
     - set PATH=%PATH%;C:\Users\appveyor\.rustup\toolchains\master\bin

clippy_dev/src/lib.rs

@@ -42,6 +42,7 @@ pub struct Lint {
 }
 
 impl Lint {
+    #[must_use]
     pub fn new(name: &str, group: &str, desc: &str, deprecation: Option<&str>, module: &str) -> Self {
         Self {
             name: name.to_lowercase(),
@@ -58,19 +59,22 @@ impl Lint {
     }
 
     /// Returns the lints in a `HashMap`, grouped by the different lint groups
+    #[must_use]
     pub fn by_lint_group(lints: &[Self]) -> HashMap<String, Vec<Self>> {
         lints
             .iter()
             .map(|lint| (lint.group.to_string(), lint.clone()))
             .into_group_map()
     }
 
+    #[must_use]
     pub fn is_internal(&self) -> bool {
         self.group.starts_with("internal")
     }
 }
 
 /// Generates the Vec items for `register_lint_group` calls in `clippy_lints/src/lib.rs`.
+#[must_use]
 pub fn gen_lint_group_list(lints: Vec<Lint>) -> Vec<String> {
     lints
         .into_iter()
@@ -86,6 +90,7 @@ pub fn gen_lint_group_list(lints: Vec<Lint>) -> Vec<String> {
 }
 
 /// Generates the `pub mod module_name` list in `clippy_lints/src/lib.rs`.
+#[must_use]
 pub fn gen_modules_list(lints: Vec<Lint>) -> Vec<String> {
     lints
         .into_iter()
@@ -103,6 +108,7 @@ pub fn gen_modules_list(lints: Vec<Lint>) -> Vec<String> {
 }
 
 /// Generates the list of lint links at the bottom of the README
+#[must_use]
 pub fn gen_changelog_lint_list(lints: Vec<Lint>) -> Vec<String> {
     let mut lint_list_sorted: Vec<Lint> = lints;
     lint_list_sorted.sort_by_key(|l| l.name.clone());
@@ -119,6 +125,7 @@ pub fn gen_changelog_lint_list(lints: Vec<Lint>) -> Vec<String> {
 }
 
 /// Generates the `register_removed` code in `./clippy_lints/src/lib.rs`.
+#[must_use]
 pub fn gen_deprecated(lints: &[Lint]) -> Vec<String> {
     lints
         .iter()

clippy_dev/src/stderr_length_check.rs

@@ -42,6 +42,7 @@ fn stderr_files() -> impl Iterator<Item = walkdir::DirEntry> {
         .filter(|f| f.path().extension() == Some(OsStr::new("stderr")))
 }
 
+#[must_use]
 fn count_linenumbers(filepath: &str) -> usize {
     if let Ok(mut file) = File::open(filepath) {
         let mut content = String::new();

clippy_lints/src/approx_const.rs

@@ -93,6 +93,7 @@ fn check_known_consts(cx: &LateContext<'_, '_>, e: &Expr, s: symbol::Symbol, mod
 /// Returns `false` if the number of significant figures in `value` are
 /// less than `min_digits`; otherwise, returns true if `value` is equal
 /// to `constant`, rounded to the number of digits present in `value`.
+#[must_use]
 fn is_approx_const(constant: f64, value: &str, min_digits: usize) -> bool {
     if value.len() <= min_digits {
         false

clippy_lints/src/assertions_on_constants.rs

@@ -1,6 +1,6 @@
 use crate::consts::{constant, Constant};
 use crate::utils::paths;
-use crate::utils::{is_direct_expn_of, is_expn_of, match_def_path, snippet_opt, span_help_and_lint};
+use crate::utils::{is_direct_expn_of, is_expn_of, match_function_call, snippet_opt, span_help_and_lint};
 use if_chain::if_chain;
 use rustc::hir::*;
 use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
@@ -145,23 +145,3 @@ fn match_assert_with_message<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &'tcx E
     }
     None
 }
-
-/// Matches a function call with the given path and returns the arguments.
-///
-/// Usage:
-///
-/// ```rust,ignore
-/// if let Some(args) = match_function_call(cx, begin_panic_call, &paths::BEGIN_PANIC);
-/// ```
-fn match_function_call<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr, path: &[&str]) -> Option<&'a [Expr]> {
-    if_chain! {
-        if let ExprKind::Call(ref fun, ref args) = expr.kind;
-        if let ExprKind::Path(ref qpath) = fun.kind;
-        if let Some(fun_def_id) = cx.tables.qpath_res(qpath, fun.hir_id).opt_def_id();
-        if match_def_path(cx, fun_def_id, path);
-        then {
-            return Some(&args)
-        }
-    };
-    None
-}

clippy_lints/src/assign_ops.rs

@@ -229,6 +229,7 @@ fn lint_misrefactored_assign_op(
     );
 }
 
+#[must_use]
 fn is_commutative(op: hir::BinOpKind) -> bool {
     use rustc::hir::BinOpKind::*;
     match op {

clippy_lints/src/bit_mask.rs

@@ -100,6 +100,7 @@ pub struct BitMask {
 }
 
 impl BitMask {
+    #[must_use]
     pub fn new(verbose_bit_mask_threshold: u64) -> Self {
         Self {
             verbose_bit_mask_threshold,
@@ -150,6 +151,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for BitMask {
     }
 }
 
+#[must_use]
 fn invert_cmp(cmp: BinOpKind) -> BinOpKind {
     match cmp {
         BinOpKind::Eq => BinOpKind::Eq,

clippy_lints/src/checked_conversions.rs

@@ -160,6 +160,7 @@ impl<'a> Conversion<'a> {
 
 impl ConversionType {
     /// Creates a conversion type if the type is allowed & conversion is valid
+    #[must_use]
     fn try_new(from: &str, to: &str) -> Option<Self> {
         if UINTS.contains(&from) {
             Some(Self::FromUnsigned)

clippy_lints/src/cognitive_complexity.rs

@@ -29,6 +29,7 @@ pub struct CognitiveComplexity {
 }
 
 impl CognitiveComplexity {
+    #[must_use]
     pub fn new(limit: u64) -> Self {
         Self {
             limit: LimitStack::new(limit),

clippy_lints/src/doc.rs

@@ -191,6 +191,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for DocMarkdown {
 /// need to keep track of
 /// the spans but this function is inspired from the later.
 #[allow(clippy::cast_possible_truncation)]
+#[must_use]
 pub fn strip_doc_comment_decoration(comment: &str, span: Span) -> (String, Vec<(usize, Span)>) {
     // one-line comments lose their prefix
     const ONELINERS: &[&str] = &["///!", "///", "//!", "//"];

clippy_lints/src/enum_variants.rs

@@ -107,6 +107,7 @@ pub struct EnumVariantNames {
 }
 
 impl EnumVariantNames {
+    #[must_use]
     pub fn new(threshold: u64) -> Self {
         Self {
             modules: Vec::new(),
@@ -123,13 +124,15 @@ impl_lint_pass!(EnumVariantNames => [
 ]);
 
 /// Returns the number of chars that match from the start
+#[must_use]
 fn partial_match(pre: &str, name: &str) -> usize {
     let mut name_iter = name.chars();
     let _ = name_iter.next_back(); // make sure the name is never fully matched
     pre.chars().zip(name_iter).take_while(|&(l, r)| l == r).count()
 }
 
 /// Returns the number of chars that match from the end
+#[must_use]
 fn partial_rmatch(post: &str, name: &str) -> usize {
     let mut name_iter = name.chars();
     let _ = name_iter.next(); // make sure the name is never fully matched
@@ -211,6 +214,7 @@ fn check_variant(
     );
 }
 
+#[must_use]
 fn to_camel_case(item_name: &str) -> String {
     let mut s = String::new();
     let mut up = true;

clippy_lints/src/excessive_precision.rs

@@ -62,6 +62,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for ExcessivePrecision {
 
 impl ExcessivePrecision {
     // None if nothing to lint, Some(suggestion) if lint necessary
+    #[must_use]
     fn check(self, sym: Symbol, fty: FloatTy) -> Option<String> {
         let max = max_digits(fty);
         let sym_str = sym.as_str();
@@ -97,6 +98,7 @@ impl ExcessivePrecision {
 /// Should we exclude the float because it has a `.0` or `.` suffix
 /// Ex `1_000_000_000.0`
 /// Ex `1_000_000_000.`
+#[must_use]
 fn dot_zero_exclusion(s: &str) -> bool {
     s.split('.').nth(1).map_or(false, |after_dec| {
         let mut decpart = after_dec.chars().take_while(|c| *c != 'e' || *c != 'E');
@@ -109,6 +111,7 @@ fn dot_zero_exclusion(s: &str) -> bool {
     })
 }
 
+#[must_use]
 fn max_digits(fty: FloatTy) -> u32 {
     match fty {
         FloatTy::F32 => f32::DIGITS,
@@ -117,6 +120,7 @@ fn max_digits(fty: FloatTy) -> u32 {
 }
 
 /// Counts the digits excluding leading zeros
+#[must_use]
 fn count_digits(s: &str) -> usize {
     // Note that s does not contain the f32/64 suffix, and underscores have been stripped
     s.chars()
@@ -138,6 +142,7 @@ enum FloatFormat {
     Normal,
 }
 impl FloatFormat {
+    #[must_use]
     fn new(s: &str) -> Self {
         s.chars()
             .find_map(|x| match x {

clippy_lints/src/explicit_write.rs

@@ -1,4 +1,4 @@
-use crate::utils::{is_expn_of, match_def_path, paths, resolve_node, span_lint, span_lint_and_sugg};
+use crate::utils::{is_expn_of, match_function_call, paths, span_lint, span_lint_and_sugg};
 use if_chain::if_chain;
 use rustc::hir::*;
 use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
@@ -41,12 +41,9 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for ExplicitWrite {
             if write_fun.ident.name == sym!(write_fmt);
             // match calls to std::io::stdout() / std::io::stderr ()
             if write_args.len() > 0;
-            if let ExprKind::Call(ref dest_fun, _) = write_args[0].kind;
-            if let ExprKind::Path(ref qpath) = dest_fun.kind;
-            if let Some(dest_fun_id) = resolve_node(cx, qpath, dest_fun.hir_id).opt_def_id();
-            if let Some(dest_name) = if match_def_path(cx, dest_fun_id, &paths::STDOUT) {
+            if let Some(dest_name) = if match_function_call(cx, &write_args[0], &paths::STDOUT).is_some() {
                 Some("stdout")
-            } else if match_def_path(cx, dest_fun_id, &paths::STDERR) {
+            } else if match_function_call(cx, &write_args[0], &paths::STDERR).is_some() {
                 Some("stderr")
             } else {
                 None

clippy_lints/src/format.rs

@@ -1,6 +1,7 @@
 use crate::utils::paths;
 use crate::utils::{
-    is_expn_of, last_path_segment, match_def_path, match_type, resolve_node, snippet, span_lint_and_then, walk_ptrs_ty,
+    is_expn_of, last_path_segment, match_def_path, match_function_call, match_type, snippet, span_lint_and_then,
+    walk_ptrs_ty,
 };
 use if_chain::if_chain;
 use rustc::hir::*;
@@ -70,19 +71,16 @@ fn span_useless_format<T: LintContext>(cx: &T, span: Span, help: &str, mut sugg:
     });
 }
 
-fn on_argumentv1_new<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr, arms: &'a [Arm]) -> Option<String> {
+fn on_argumentv1_new<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr, arms: &'tcx [Arm]) -> Option<String> {
     if_chain! {
         if let ExprKind::AddrOf(_, ref format_args) = expr.kind;
         if let ExprKind::Array(ref elems) = arms[0].body.kind;
         if elems.len() == 1;
-        if let ExprKind::Call(ref fun, ref args) = elems[0].kind;
-        if let ExprKind::Path(ref qpath) = fun.kind;
-        if let Some(did) = resolve_node(cx, qpath, fun.hir_id).opt_def_id();
-        if match_def_path(cx, did, &paths::FMT_ARGUMENTV1_NEW);
+        if let Some(args) = match_function_call(cx, &elems[0], &paths::FMT_ARGUMENTV1_NEW);
         // matches `core::fmt::Display::fmt`
         if args.len() == 2;
         if let ExprKind::Path(ref qpath) = args[1].kind;
-        if let Some(did) = resolve_node(cx, qpath, args[1].hir_id).opt_def_id();
+        if let Some(did) = cx.tables.qpath_res(qpath, args[1].hir_id).opt_def_id();
         if match_def_path(cx, did, &paths::DISPLAY_FMT_METHOD);
         // check `(arg0,)` in match block
         if let PatKind::Tuple(ref pats, None) = arms[0].pat.kind;
@@ -114,11 +112,8 @@ fn on_argumentv1_new<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr, arm
 
 fn on_new_v1<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) -> Option<String> {
     if_chain! {
-        if let ExprKind::Call(ref fun, ref args) = expr.kind;
+        if let Some(args) = match_function_call(cx, expr, &paths::FMT_ARGUMENTS_NEW_V1);
         if args.len() == 2;
-        if let ExprKind::Path(ref qpath) = fun.kind;
-        if let Some(did) = resolve_node(cx, qpath, fun.hir_id).opt_def_id();
-        if match_def_path(cx, did, &paths::FMT_ARGUMENTS_NEW_V1);
         // Argument 1 in `new_v1()`
         if let ExprKind::AddrOf(_, ref arr) = args[0].kind;
         if let ExprKind::Array(ref pieces) = arr.kind;
@@ -144,11 +139,8 @@ fn on_new_v1<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) -> Option<S
 
 fn on_new_v1_fmt<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) -> Option<String> {
     if_chain! {
-        if let ExprKind::Call(ref fun, ref args) = expr.kind;
+        if let Some(args) = match_function_call(cx, expr, &paths::FMT_ARGUMENTS_NEW_V1_FORMATTED);
         if args.len() == 3;
-        if let ExprKind::Path(ref qpath) = fun.kind;
-        if let Some(did) = resolve_node(cx, qpath, fun.hir_id).opt_def_id();
-        if match_def_path(cx, did, &paths::FMT_ARGUMENTS_NEW_V1_FORMATTED);
         if check_unformatted(&args[2]);
         // Argument 1 in `new_v1_formatted()`
         if let ExprKind::AddrOf(_, ref arr) = args[0].kind;

clippy_lints/src/formatting.rs

@@ -235,6 +235,7 @@ fn check_else(cx: &EarlyContext<'_>, expr: &Expr) {
     }
 }
 
+#[must_use]
 fn has_unary_equivalent(bin_op: BinOpKind) -> bool {
     // &, *, -
     bin_op == BinOpKind::And || bin_op == BinOpKind::Mul || bin_op == BinOpKind::Sub