Auto merge of #5029 - flip1995:wildcard_imports, r=phansch

New Lint: `wildcard imports`

Fixes #1228

### A few notes:
- I put this lint in the pedantic group, even though in the issue restriction was mentioned.
- Every fallout fix was automatically applied by `cargo fix` (This produced 3 `unused_imports` warnings) and are in commit 7e834c8. So reverting these changes wouldn't be a problem.

### A few ideas:
- A configuration to specify the amount of imported Items, where a `*` might be better.
- ~~A configuration to disable the lint for enums. Or just disable the lint for enums, since there is [`enum_glob_use`](https://rust-lang.github.io/rust-clippy/master/index.html#enum_glob_use)~~ I moved `enum_glob_use` into this lint in 12937f0

### A few quotes from the issue:
> Is there a way to ask the compiler about the modules or symbols that the current file is using?

Yes there is. I found it, once I was nearly finished implementing it myself. See 321d64a

> one hard optional feature would be to figure out what is currently used and add a suggestion to replace it with a full import list.

Yeah that was pretty hard, until I found the query for this. Queries are cool, but too hard to find.

> FWIW VS Code and Intellij IDEA both offer imports deglobbing which replace * with required imports.

And now, Clippy can do this too! 🎉

---

Your thoughts on the notes/ideas?

changelog: Add new lint [`wildcard imports`]. Add suggestion to [`enum_glob_use`]

CHANGELOG.md

@@ -1419,6 +1419,7 @@ Released 2018-09-13
 [`while_let_on_iterator`]: https://rust-lang.github.io/rust-clippy/master/index.html#while_let_on_iterator
 [`wildcard_dependencies`]: https://rust-lang.github.io/rust-clippy/master/index.html#wildcard_dependencies
 [`wildcard_enum_match_arm`]: https://rust-lang.github.io/rust-clippy/master/index.html#wildcard_enum_match_arm
+[`wildcard_imports`]: https://rust-lang.github.io/rust-clippy/master/index.html#wildcard_imports
 [`wildcard_in_or_patterns`]: https://rust-lang.github.io/rust-clippy/master/index.html#wildcard_in_or_patterns
 [`write_literal`]: https://rust-lang.github.io/rust-clippy/master/index.html#write_literal
 [`write_with_newline`]: https://rust-lang.github.io/rust-clippy/master/index.html#write_with_newline

README.md

@@ -5,7 +5,7 @@
 
 A collection of lints to catch common mistakes and improve your [Rust](https://github.com/rust-lang/rust) code.
 
-[There are 356 lints included in this crate!](https://rust-lang.github.io/rust-clippy/master/index.html)
+[There are 357 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:
 

clippy_dev/src/main.rs

@@ -1,7 +1,10 @@
 #![cfg_attr(feature = "deny-warnings", deny(warnings))]
 
 use clap::{App, Arg, SubCommand};
-use clippy_dev::*;
+use clippy_dev::{
+    gather_all, gen_changelog_lint_list, gen_deprecated, gen_lint_group_list, gen_modules_list, gen_register_lint_list,
+    replace_region_in_file, Lint, DOCS_LINK,
+};
 use std::path::Path;
 
 mod fmt;

clippy_lints/src/approx_const.rs

@@ -1,5 +1,5 @@
 use crate::utils::span_lint;
-use rustc_hir::*;
+use rustc_hir::{Expr, ExprKind};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::symbol;

clippy_lints/src/as_conversions.rs

@@ -1,7 +1,7 @@
 use rustc::lint::in_external_macro;
 use rustc_lint::{EarlyContext, EarlyLintPass, LintContext};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
-use syntax::ast::*;
+use syntax::ast::{Expr, ExprKind};
 
 use crate::utils::span_lint_and_help;
 

clippy_lints/src/assertions_on_constants.rs

@@ -2,7 +2,7 @@ use crate::consts::{constant, Constant};
 use crate::utils::paths;
 use crate::utils::{is_direct_expn_of, is_expn_of, match_function_call, snippet_opt, span_lint_and_help};
 use if_chain::if_chain;
-use rustc_hir::*;
+use rustc_hir::{Expr, ExprKind, PatKind, UnOp};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use syntax::ast::LitKind;

clippy_lints/src/assign_ops.rs

@@ -231,7 +231,9 @@ fn lint_misrefactored_assign_op(
 
 #[must_use]
 fn is_commutative(op: hir::BinOpKind) -> bool {
-    use rustc_hir::BinOpKind::*;
+    use rustc_hir::BinOpKind::{
+        Add, And, BitAnd, BitOr, BitXor, Div, Eq, Ge, Gt, Le, Lt, Mul, Ne, Or, Rem, Shl, Shr, Sub,
+    };
     match op {
         Add | Mul | And | Or | BitXor | BitAnd | BitOr | Eq | Ne => true,
         Sub | Div | Rem | Shl | Shr | Lt | Le | Ge | Gt => false,

clippy_lints/src/atomic_ordering.rs

@@ -2,7 +2,7 @@ use crate::utils::{match_def_path, span_lint_and_help};
 use if_chain::if_chain;
 use rustc::ty;
 use rustc_hir::def_id::DefId;
-use rustc_hir::*;
+use rustc_hir::{Expr, ExprKind};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 

clippy_lints/src/attrs.rs

@@ -1,6 +1,6 @@
 //! checks for attributes
 
-use crate::reexport::*;
+use crate::reexport::Name;
 use crate::utils::{
     first_line_of_span, is_present_in_source, match_def_path, paths, snippet_opt, span_lint, span_lint_and_sugg,
     span_lint_and_then, without_block_comments,
@@ -9,7 +9,9 @@ use if_chain::if_chain;
 use rustc::lint::in_external_macro;
 use rustc::ty;
 use rustc_errors::Applicability;
-use rustc_hir::*;
+use rustc_hir::{
+    Block, Expr, ExprKind, ImplItem, ImplItemKind, Item, ItemKind, StmtKind, TraitItem, TraitItemKind, TraitMethod,
+};
 use rustc_lint::{CheckLintNameResult, EarlyContext, EarlyLintPass, LateContext, LateLintPass, LintContext};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::source_map::Span;

clippy_lints/src/bit_mask.rs

@@ -3,7 +3,7 @@ use crate::utils::sugg::Sugg;
 use crate::utils::{span_lint, span_lint_and_then};
 use if_chain::if_chain;
 use rustc_errors::Applicability;
-use rustc_hir::*;
+use rustc_hir::{BinOpKind, Expr, ExprKind};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::{declare_tool_lint, impl_lint_pass};
 use rustc_span::source_map::Span;

clippy_lints/src/blacklisted_name.rs

@@ -1,6 +1,6 @@
 use crate::utils::span_lint;
 use rustc_data_structures::fx::FxHashSet;
-use rustc_hir::*;
+use rustc_hir::{Pat, PatKind};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::{declare_tool_lint, impl_lint_pass};
 

clippy_lints/src/block_in_if_condition.rs

@@ -1,10 +1,10 @@
-use crate::utils::*;
+use crate::utils::{differing_macro_contexts, higher, snippet_block_with_applicability, span_lint, span_lint_and_sugg};
 use matches::matches;
 use rustc::hir::map::Map;
 use rustc::lint::in_external_macro;
 use rustc_errors::Applicability;
 use rustc_hir::intravisit::{walk_expr, NestedVisitorMap, Visitor};
-use rustc_hir::*;
+use rustc_hir::{BlockCheckMode, Expr, ExprKind};
 use rustc_lint::{LateContext, LateLintPass, LintContext};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 

clippy_lints/src/booleans.rs

@@ -5,8 +5,8 @@ use crate::utils::{
 use if_chain::if_chain;
 use rustc::hir::map::Map;
 use rustc_errors::Applicability;
-use rustc_hir::intravisit::*;
-use rustc_hir::*;
+use rustc_hir::intravisit::{walk_expr, FnKind, NestedVisitorMap, Visitor};
+use rustc_hir::{BinOpKind, Body, Expr, ExprKind, FnDecl, HirId, UnOp};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::source_map::Span;
@@ -161,7 +161,7 @@ struct SuggestContext<'a, 'tcx, 'v> {
 
 impl<'a, 'tcx, 'v> SuggestContext<'a, 'tcx, 'v> {
     fn recurse(&mut self, suggestion: &Bool) -> Option<()> {
-        use quine_mc_cluskey::Bool::*;
+        use quine_mc_cluskey::Bool::{And, False, Not, Or, Term, True};
         match suggestion {
             True => {
                 self.output.push_str("true");
@@ -277,7 +277,7 @@ fn suggest(cx: &LateContext<'_, '_>, suggestion: &Bool, terminals: &[&Expr<'_>])
 }
 
 fn simple_negate(b: Bool) -> Bool {
-    use quine_mc_cluskey::Bool::*;
+    use quine_mc_cluskey::Bool::{And, False, Not, Or, Term, True};
     match b {
         True => False,
         False => True,
@@ -325,7 +325,7 @@ fn terminal_stats(b: &Bool) -> Stats {
             &Term(n) => stats.terminals[n as usize] += 1,
         }
     }
-    use quine_mc_cluskey::Bool::*;
+    use quine_mc_cluskey::Bool::{And, False, Not, Or, Term, True};
     let mut stats = Stats::default();
     recurse(b, &mut stats);
     stats

clippy_lints/src/bytecount.rs

@@ -5,7 +5,7 @@ use crate::utils::{
 use if_chain::if_chain;
 use rustc::ty;
 use rustc_errors::Applicability;
-use rustc_hir::*;
+use rustc_hir::{BinOpKind, BorrowKind, Expr, ExprKind, UnOp};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use syntax::ast::{Name, UintTy};

clippy_lints/src/cargo_common_metadata.rs

@@ -6,7 +6,7 @@ use crate::utils::span_lint;
 use rustc_lint::{EarlyContext, EarlyLintPass};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::source_map::DUMMY_SP;
-use syntax::ast::*;
+use syntax::ast::Crate;
 
 declare_clippy_lint! {
     /// **What it does:** Checks to see if all common metadata is defined in

clippy_lints/src/checked_conversions.rs

@@ -3,7 +3,7 @@
 use if_chain::if_chain;
 use rustc::lint::in_external_macro;
 use rustc_errors::Applicability;
-use rustc_hir::*;
+use rustc_hir::{BinOp, BinOpKind, Expr, ExprKind, QPath, TyKind};
 use rustc_lint::{LateContext, LateLintPass, LintContext};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use syntax::ast::LitKind;

clippy_lints/src/cognitive_complexity.rs

@@ -2,7 +2,7 @@
 
 use rustc::hir::map::Map;
 use rustc_hir::intravisit::{walk_expr, FnKind, NestedVisitorMap, Visitor};
-use rustc_hir::*;
+use rustc_hir::{Body, Expr, ExprKind, FnDecl, HirId};
 use rustc_lint::{LateContext, LateLintPass, LintContext};
 use rustc_session::{declare_tool_lint, impl_lint_pass};
 use rustc_span::source_map::Span;

clippy_lints/src/comparison_chain.rs

@@ -1,7 +1,7 @@
 use crate::utils::{
     get_trait_def_id, if_sequence, implements_trait, parent_node_is_if_expr, paths, span_lint_and_help, SpanlessEq,
 };
-use rustc_hir::*;
+use rustc_hir::{BinOpKind, Expr, ExprKind};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 

clippy_lints/src/consts.rs

@@ -7,13 +7,13 @@ use rustc::ty::{self, Ty, TyCtxt};
 use rustc::{bug, span_bug};
 use rustc_data_structures::sync::Lrc;
 use rustc_hir::def::{DefKind, Res};
-use rustc_hir::*;
+use rustc_hir::{BinOp, BinOpKind, Block, Expr, ExprKind, HirId, QPath, UnOp};
 use rustc_lint::LateContext;
 use rustc_span::symbol::Symbol;
 use std::cmp::Ordering::{self, Equal};
 use std::convert::TryInto;
 use std::hash::{Hash, Hasher};
-use syntax::ast::{FloatTy, LitKind};
+use syntax::ast::{FloatTy, LitFloatType, LitKind};
 
 /// A `LitKind`-like enum to fold constant `Expr`s into.
 #[derive(Debug, Clone)]
@@ -152,8 +152,6 @@ impl Constant {
 
 /// Parses a `LitKind` to a `Constant`.
 pub fn lit_to_constant(lit: &LitKind, ty: Option<Ty<'_>>) -> Constant {
-    use syntax::ast::*;
-
     match *lit {
         LitKind::Str(ref is, _) => Constant::Str(is.to_string()),
         LitKind::Byte(b) => Constant::Int(u128::from(b)),
@@ -277,7 +275,7 @@ impl<'c, 'cc> ConstEvalLateContext<'c, 'cc> {
 
     #[allow(clippy::cast_possible_wrap)]
     fn constant_not(&self, o: &Constant, ty: Ty<'_>) -> Option<Constant> {
-        use self::Constant::*;
+        use self::Constant::{Bool, Int};
         match *o {
             Bool(b) => Some(Bool(!b)),
             Int(value) => {
@@ -293,7 +291,7 @@ impl<'c, 'cc> ConstEvalLateContext<'c, 'cc> {
     }
 
     fn constant_negate(&self, o: &Constant, ty: Ty<'_>) -> Option<Constant> {
-        use self::Constant::*;
+        use self::Constant::{Int, F32, F64};
         match *o {
             Int(value) => {
                 let ity = match ty.kind {

clippy_lints/src/copies.rs

@@ -2,7 +2,7 @@ use crate::utils::{get_parent_expr, higher, if_sequence, same_tys, snippet, span
 use crate::utils::{SpanlessEq, SpanlessHash};
 use rustc::ty::Ty;
 use rustc_data_structures::fx::FxHashMap;
-use rustc_hir::*;
+use rustc_hir::{Arm, Block, Expr, ExprKind, MatchSource, Pat, PatKind};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::symbol::Symbol;

clippy_lints/src/default_trait_access.rs

@@ -1,7 +1,7 @@
 use if_chain::if_chain;
 use rustc::ty;
 use rustc_errors::Applicability;
-use rustc_hir::*;
+use rustc_hir::{Expr, ExprKind, QPath};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 

clippy_lints/src/derive.rs

@@ -2,7 +2,7 @@ use crate::utils::paths;
 use crate::utils::{is_automatically_derived, is_copy, match_path, span_lint_and_then};
 use if_chain::if_chain;
 use rustc::ty::{self, Ty};
-use rustc_hir::*;
+use rustc_hir::{Item, ItemKind, TraitRef};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::source_map::Span;

clippy_lints/src/doc.rs

@@ -350,7 +350,7 @@ fn check_attrs<'a>(cx: &LateContext<'_, '_>, valid_idents: &FxHashSet<String>, a
     let parser = pulldown_cmark::Parser::new(&doc).into_offset_iter();
     // Iterate over all `Events` and combine consecutive events into one
     let events = parser.coalesce(|previous, current| {
-        use pulldown_cmark::Event::*;
+        use pulldown_cmark::Event::Text;
 
         let previous_range = previous.1;
         let current_range = current.1;
@@ -374,8 +374,10 @@ fn check_doc<'a, Events: Iterator<Item = (pulldown_cmark::Event<'a>, Range<usize
     spans: &[(usize, Span)],
 ) -> DocHeaders {
     // true if a safety header was found
-    use pulldown_cmark::Event::*;
-    use pulldown_cmark::Tag::*;
+    use pulldown_cmark::Event::{
+        Code, End, FootnoteReference, HardBreak, Html, Rule, SoftBreak, Start, TaskListMarker, Text,
+    };
+    use pulldown_cmark::Tag::{CodeBlock, Heading, Link};
 
     let mut headers = DocHeaders {
         safety: false,

clippy_lints/src/double_comparison.rs

@@ -1,7 +1,7 @@
 //! Lint on unnecessary double comparisons. Some examples:
 
 use rustc_errors::Applicability;
-use rustc_hir::*;
+use rustc_hir::{BinOpKind, Expr, ExprKind};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::source_map::Span;

clippy_lints/src/double_parens.rs

@@ -1,7 +1,7 @@
 use crate::utils::span_lint;
 use rustc_lint::{EarlyContext, EarlyLintPass};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
-use syntax::ast::*;
+use syntax::ast::{Expr, ExprKind};
 
 declare_clippy_lint! {
     /// **What it does:** Checks for unnecessary double parentheses.

clippy_lints/src/drop_bounds.rs

@@ -1,6 +1,6 @@
 use crate::utils::{match_def_path, paths, span_lint};
 use if_chain::if_chain;
-use rustc_hir::*;
+use rustc_hir::{GenericBound, GenericParam, WhereBoundPredicate, WherePredicate};
 use rustc_lint::LateLintPass;
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 

clippy_lints/src/drop_forget_ref.rs

@@ -1,7 +1,7 @@
 use crate::utils::{is_copy, match_def_path, paths, qpath_res, span_lint_and_note};
 use if_chain::if_chain;
 use rustc::ty;
-use rustc_hir::*;
+use rustc_hir::{Expr, ExprKind};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 

clippy_lints/src/duration_subsec.rs

@@ -1,6 +1,6 @@
 use if_chain::if_chain;
 use rustc_errors::Applicability;
-use rustc_hir::*;
+use rustc_hir::{BinOpKind, Expr, ExprKind};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::source_map::Spanned;

clippy_lints/src/else_if_without_else.rs

@@ -3,7 +3,7 @@
 use rustc::lint::in_external_macro;
 use rustc_lint::{EarlyContext, EarlyLintPass, LintContext};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
-use syntax::ast::*;
+use syntax::ast::{Expr, ExprKind};
 
 use crate::utils::span_lint_and_help;
 

clippy_lints/src/empty_enum.rs

@@ -1,7 +1,7 @@
 //! lint when there is an enum with no variants
 
 use crate::utils::span_lint_and_then;
-use rustc_hir::*;
+use rustc_hir::{Item, ItemKind};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 

clippy_lints/src/entry.rs

@@ -5,7 +5,7 @@ use if_chain::if_chain;
 use rustc::hir::map::Map;
 use rustc_errors::Applicability;
 use rustc_hir::intravisit::{walk_expr, NestedVisitorMap, Visitor};
-use rustc_hir::*;
+use rustc_hir::{BorrowKind, Expr, ExprKind, UnOp};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::source_map::Span;

clippy_lints/src/enum_clike.rs

@@ -5,7 +5,7 @@ use crate::consts::{miri_to_const, Constant};
 use crate::utils::span_lint;
 use rustc::ty;
 use rustc::ty::util::IntTypeExt;
-use rustc_hir::*;
+use rustc_hir::{Item, ItemKind};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use std::convert::TryFrom;