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

New Lint: `wildcard imports`

Fixes rust-lang#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`]

Author: bors

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;