Auto merge of rust-lang#5666 - flip1995:rollup-yjyvvbg, r=flip1995

Rollup of 3 pull requests

Successful merges:

 - rust-lang#5637 (new lint: vec_resize_to_zero)
 - rust-lang#5656 (len_zero: skip ranges if feature `range_is_empty` is not enabled)
 - rust-lang#5663 (add testcase that no longer ICEs)

Failed merges:

r? @ghost

changelog: rollup

CHANGELOG.md

@@ -1630,6 +1630,7 @@ Released 2018-09-13
 [`useless_transmute`]: https://rust-lang.github.io/rust-clippy/master/index.html#useless_transmute
 [`useless_vec`]: https://rust-lang.github.io/rust-clippy/master/index.html#useless_vec
 [`vec_box`]: https://rust-lang.github.io/rust-clippy/master/index.html#vec_box
+[`vec_resize_to_zero`]: https://rust-lang.github.io/rust-clippy/master/index.html#vec_resize_to_zero
 [`verbose_bit_mask`]: https://rust-lang.github.io/rust-clippy/master/index.html#verbose_bit_mask
 [`verbose_file_reads`]: https://rust-lang.github.io/rust-clippy/master/index.html#verbose_file_reads
 [`vtable_address_comparisons`]: https://rust-lang.github.io/rust-clippy/master/index.html#vtable_address_comparisons

clippy_lints/src/len_zero.rs

@@ -1,4 +1,4 @@
-use crate::utils::{get_item_name, snippet_with_applicability, span_lint, span_lint_and_sugg, walk_ptrs_ty};
+use crate::utils::{get_item_name, higher, snippet_with_applicability, span_lint, span_lint_and_sugg, walk_ptrs_ty};
 use rustc_ast::ast::LitKind;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_errors::Applicability;
@@ -259,6 +259,17 @@ fn check_len(
 
 /// Checks if this type has an `is_empty` method.
 fn has_is_empty(cx: &LateContext<'_, '_>, expr: &Expr<'_>) -> bool {
+ /// Special case ranges until `range_is_empty` is stabilized. See issue 3807.
+ fn should_skip_range(cx: &LateContext<'_, '_>, expr: &Expr<'_>) -> bool {
+ higher::range(cx, expr).map_or(false, |_| {
+ !cx.tcx
+ .features()
+ .declared_lib_features
+ .iter()
+ .any(|(name, _)| name.as_str() == "range_is_empty")
+ })
+ }
+
  /// Gets an `AssocItem` and return true if it matches `is_empty(self)`.
  fn is_is_empty(cx: &LateContext<'_, '_>, item: &ty::AssocItem) -> bool {
  if let ty::AssocKind::Fn = item.kind {
@@ -284,6 +295,10 @@ fn has_is_empty(cx: &LateContext<'_, '_>, expr: &Expr<'_>) -> bool {
  })
  }
 
+ if should_skip_range(cx, expr) {
+ return false;
+ }
+
  let ty = &walk_ptrs_ty(cx.tables.expr_ty(expr));
  match ty.kind {
  ty::Dynamic(ref tt, ..) => {

clippy_lints/src/lib.rs

@@ -325,6 +325,7 @@ mod unwrap;
 mod use_self;
 mod useless_conversion;
 mod vec;
+mod vec_resize_to_zero;
 mod verbose_file_reads;
 mod wildcard_dependencies;
 mod wildcard_imports;
@@ -847,6 +848,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
  &utils::internal_lints::OUTER_EXPN_EXPN_DATA,
  &utils::internal_lints::PRODUCE_ICE,
  &vec::USELESS_VEC,
+ &vec_resize_to_zero::VEC_RESIZE_TO_ZERO,
  &verbose_file_reads::VERBOSE_FILE_READS,
  &wildcard_dependencies::WILDCARD_DEPENDENCIES,
  &wildcard_imports::ENUM_GLOB_USE,
@@ -1062,6 +1064,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
  store.register_early_pass(|| box manual_non_exhaustive::ManualNonExhaustive);
  store.register_late_pass(|| box manual_async_fn::ManualAsyncFn);
  store.register_early_pass(|| box redundant_field_names::RedundantFieldNames);
+ store.register_late_pass(|| box vec_resize_to_zero::VecResizeToZero);
  let single_char_binding_names_threshold = conf.single_char_binding_names_threshold;
  store.register_early_pass(move || box non_expressive_names::NonExpressiveNames {
  single_char_binding_names_threshold,
@@ -1430,6 +1433,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
  LintId::of(&unwrap::UNNECESSARY_UNWRAP),
  LintId::of(&useless_conversion::USELESS_CONVERSION),
  LintId::of(&vec::USELESS_VEC),
+ LintId::of(&vec_resize_to_zero::VEC_RESIZE_TO_ZERO),
  LintId::of(&write::PRINTLN_EMPTY_STRING),
  LintId::of(&write::PRINT_LITERAL),
  LintId::of(&write::PRINT_WITH_NEWLINE),
@@ -1677,6 +1681,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
  LintId::of(&unnamed_address::VTABLE_ADDRESS_COMPARISONS),
  LintId::of(&unused_io_amount::UNUSED_IO_AMOUNT),
  LintId::of(&unwrap::PANICKING_UNWRAP),
+ LintId::of(&vec_resize_to_zero::VEC_RESIZE_TO_ZERO),
  ]);
 
  store.register_group(true, "clippy::perf", Some("clippy_perf"), vec![

clippy_lints/src/utils/paths.rs

@@ -138,5 +138,6 @@ pub const VEC_AS_SLICE: [&str; 4] = ["alloc", "vec", "Vec", "as_slice"];
 pub const VEC_DEQUE: [&str; 4] = ["alloc", "collections", "vec_deque", "VecDeque"];
 pub const VEC_FROM_ELEM: [&str; 3] = ["alloc", "vec", "from_elem"];
 pub const VEC_NEW: [&str; 4] = ["alloc", "vec", "Vec", "new"];
+pub const VEC_RESIZE: [&str; 4] = ["alloc", "vec", "Vec", "resize"];
 pub const WEAK_ARC: [&str; 3] = ["alloc", "sync", "Weak"];
 pub const WEAK_RC: [&str; 3] = ["alloc", "rc", "Weak"];

clippy_lints/src/vec_resize_to_zero.rs

@@ -0,0 +1,59 @@
+use crate::utils::span_lint_and_then;
+use if_chain::if_chain;
+use rustc_errors::Applicability;
+use rustc_hir::{Expr, ExprKind};
+use rustc_lint::{LateContext, LateLintPass};
+use rustc_session::{declare_lint_pass, declare_tool_lint};
+use rustc_span::source_map::Spanned;
+
+use crate::utils::{match_def_path, paths};
+use rustc_ast::ast::LitKind;
+use rustc_hir as hir;
+
+declare_clippy_lint! {
+ /// **What it does:** Finds occurences of `Vec::resize(0, an_int)`
+ ///
+ /// **Why is this bad?** This is probably an argument inversion mistake.
+ ///
+ /// **Known problems:** None.
+ ///
+ /// **Example:**
+ /// ```rust
+ /// vec!(1, 2, 3, 4, 5).resize(0, 5)
+ /// ```
+ pub VEC_RESIZE_TO_ZERO,
+ correctness,
+ "emptying a vector with `resize(0, an_int)` instead of `clear()` is probably an argument inversion mistake"
+}
+
+declare_lint_pass!(VecResizeToZero => [VEC_RESIZE_TO_ZERO]);
+
+impl<'a, 'tcx> LateLintPass<'a, 'tcx> for VecResizeToZero {
+ fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr<'_>) {
+ if_chain! {
+ if let hir::ExprKind::MethodCall(path_segment, _, ref args) = expr.kind;
+ if let Some(method_def_id) = cx.tables.type_dependent_def_id(expr.hir_id);
+ if match_def_path(cx, method_def_id, &paths::VEC_RESIZE) && args.len() == 3;
+ if let ExprKind::Lit(Spanned { node: LitKind::Int(0, _), .. }) = args[1].kind;
+ if let ExprKind::Lit(Spanned { node: LitKind::Int(..), .. }) = args[2].kind;
+ then {
+ let method_call_span = expr.span.with_lo(path_segment.ident.span.lo());
+ span_lint_and_then(
+ cx,
+ VEC_RESIZE_TO_ZERO,
+ expr.span,
+ "emptying a vector with `resize`",
+ |db| {
+ db.help("the arguments may be inverted...");
+ db.span_suggestion(
+ method_call_span,
+ "...or you can empty the vector with",
+ "clear()".to_string(),
+ Applicability::MaybeIncorrect,
+ );
+ },
+ );
+ }
+ }
+ }
+}

src/lintlist/mod.rs

@@ -2460,6 +2460,13 @@ pub static ref ALL_LINTS: Vec<Lint> = vec![
  deprecation: None,
  module: "types",
  },
+ Lint {
+ name: "vec_resize_to_zero",
+ group: "correctness",
+ desc: "emptying a vector with `resize(0, an_int)` instead of `clear()` is probably an argument inversion mistake",
+ deprecation: None,
+ module: "vec_resize_to_zero",
+ },
  Lint {
  name: "verbose_bit_mask",
  group: "style",

tests/ui/crashes/ice-3969.rs

@@ -0,0 +1,51 @@
+// https://github.com/rust-lang/rust-clippy/issues/3969
+// used to crash: error: internal compiler error:
+// src/librustc_traits/normalize_erasing_regions.rs:43: could not fully normalize `<i32 as
+// std::iter::Iterator>::Item test from rustc ./ui/trivial-bounds/trivial-bounds-inconsistent.rs
+
+// Check that tautalogically false bounds are accepted, and are used
+// in type inference.
+#![feature(trivial_bounds)]
+#![allow(unused)]
+
+trait A {}
+
+impl A for i32 {}
+
+struct Dst<X: ?Sized> {
+ x: X,
+}
+
+struct TwoStrs(str, str)
+where
+ str: Sized;
+
+fn unsized_local()
+where
+ for<'a> Dst<A + 'a>: Sized,
+{
+ let x: Dst<A> = *(Box::new(Dst { x: 1 }) as Box<Dst<A>>);
+}
+
+fn return_str() -> str
+where
+ str: Sized,
+{
+ *"Sized".to_string().into_boxed_str()
+}
+
+fn use_op(s: String) -> String
+where
+ String: ::std::ops::Neg<Output = String>,
+{
+ -s
+}
+
+fn use_for()
+where
+ i32: Iterator,
+{
+ for _ in 2i32 {}
+}
+
+fn main() {}

tests/ui/crashes/ice-3969.stderr

@@ -0,0 +1,22 @@
+error: trait objects without an explicit `dyn` are deprecated
+ --> $DIR/ice-3969.rs:25:17
+ |
+LL | for<'a> Dst<A + 'a>: Sized,
+ | ^^^^^^ help: use `dyn`: `dyn A + 'a`
+ |
+ = note: `-D bare-trait-objects` implied by `-D warnings`
+
+error: trait objects without an explicit `dyn` are deprecated
+ --> $DIR/ice-3969.rs:27:16
+ |
+LL | let x: Dst<A> = *(Box::new(Dst { x: 1 }) as Box<Dst<A>>);
+ | ^ help: use `dyn`: `dyn A`
+
+error: trait objects without an explicit `dyn` are deprecated
+ --> $DIR/ice-3969.rs:27:57
+ |
+LL | let x: Dst<A> = *(Box::new(Dst { x: 1 }) as Box<Dst<A>>);
+ | ^ help: use `dyn`: `dyn A`
+
+error: aborting due to 3 previous errors
+

tests/ui/len_zero.fixed

@@ -141,3 +141,11 @@ fn main() {
 fn test_slice(b: &[u8]) {
  if !b.is_empty() {}
 }
+
+mod issue_3807 {
+ // Avoid suggesting changes to ranges if the user did not enable `range_is_empty`.
+ // See https://github.com/rust-lang/rust/issues/48111#issuecomment-445132965
+ fn no_suggestion() {
+ let _ = (0..42).len() == 0;
+ }
+}

tests/ui/len_zero.rs

@@ -141,3 +141,11 @@ fn main() {
 fn test_slice(b: &[u8]) {
  if b.len() != 0 {}
 }
+
+mod issue_3807 {
+ // Avoid suggesting changes to ranges if the user did not enable `range_is_empty`.
+ // See https://github.com/rust-lang/rust/issues/48111#issuecomment-445132965
+ fn no_suggestion() {
+ let _ = (0..42).len() == 0;
+ }
+}

tests/ui/len_zero_ranges.fixed

@@ -0,0 +1,14 @@
+// run-rustfix
+
+#![feature(range_is_empty)]
+#![warn(clippy::len_zero)]
+#![allow(unused)]
+
+mod issue_3807 {
+ // With the feature enabled, `is_empty` should be suggested
+ fn suggestion_is_fine() {
+ let _ = (0..42).is_empty();
+ }
+}
+
+fn main() {}

tests/ui/len_zero_ranges.rs

@@ -0,0 +1,14 @@
+// run-rustfix
+
+#![feature(range_is_empty)]
+#![warn(clippy::len_zero)]
+#![allow(unused)]
+
+mod issue_3807 {
+ // With the feature enabled, `is_empty` should be suggested
+ fn suggestion_is_fine() {
+ let _ = (0..42).len() == 0;
+ }
+}
+
+fn main() {}

tests/ui/len_zero_ranges.stderr

@@ -0,0 +1,10 @@
+error: length comparison to zero
+ --> $DIR/len_zero_ranges.rs:10:17
+ |
+LL | let _ = (0..42).len() == 0;
+ | ^^^^^^^^^^^^^^^^^^ help: using `is_empty` is clearer and more explicit: `(0..42).is_empty()`
+ |
+ = note: `-D clippy::len-zero` implied by `-D warnings`
+
+error: aborting due to previous error
+

tests/ui/vec_resize_to_zero.rs

@@ -0,0 +1,15 @@
+#![warn(clippy::vec_resize_to_zero)]
+
+fn main() {
+ // applicable here
+ vec![1, 2, 3, 4, 5].resize(0, 5);
+
+ // not applicable
+ vec![1, 2, 3, 4, 5].resize(2, 5);
+
+ // applicable here, but only implemented for integer litterals for now
+ vec!["foo", "bar", "baz"].resize(0, "bar");
+
+ // not applicable
+ vec!["foo", "bar", "baz"].resize(2, "bar")
+}

tests/ui/vec_resize_to_zero.stderr

@@ -0,0 +1,13 @@
+error: emptying a vector with `resize`
+ --> $DIR/vec_resize_to_zero.rs:5:5
+ |
+LL | vec![1, 2, 3, 4, 5].resize(0, 5);
+ | ^^^^^^^^^^^^^^^^^^^^------------
+ | |
+ | help: ...or you can empty the vector with: `clear()`
+ |
+ = note: `-D clippy::vec-resize-to-zero` implied by `-D warnings`
+ = help: the arguments may be inverted...
+
+error: aborting due to previous error
+