Auto merge of #5279 - DevinR528:macro-use-sugg, r=flip1995

Macro use sugg

changelog: Add auto applicable suggstion to macro_use_imports

fixes #5275

<s>Where exactly is the `wildcard_imports_helper` I haven't been able to import anything ex.
`use lazy_static;` or something like for that I get version/compiler conflicts?</s>
Found it.

Should we also check for `#[macro_use] extern crate`, although this is still depended on for stuff like `rustc_private`?

clippy_lints/src/lib.rs

@@ -1062,7 +1062,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     store.register_early_pass(|| box option_env_unwrap::OptionEnvUnwrap);
     let warn_on_all_wildcard_imports = conf.warn_on_all_wildcard_imports;
     store.register_late_pass(move || box wildcard_imports::WildcardImports::new(warn_on_all_wildcard_imports));
-    store.register_early_pass(|| box macro_use::MacroUseImports);
     store.register_late_pass(|| box verbose_file_reads::VerboseFileReads);
     store.register_late_pass(|| box redundant_pub_crate::RedundantPubCrate::default());
     store.register_late_pass(|| box unnamed_address::UnnamedAddress);
@@ -1080,6 +1079,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         single_char_binding_names_threshold,
     });
     store.register_early_pass(|| box unnested_or_patterns::UnnestedOrPatterns);
+    store.register_late_pass(|| box macro_use::MacroUseImports::default());
 
     store.register_group(true, "clippy::restriction", Some("clippy_restriction"), vec![
         LintId::of(&arithmetic::FLOAT_ARITHMETIC),

clippy_lints/src/macro_use.rs

@@ -1,18 +1,21 @@
-use crate::utils::{snippet, span_lint_and_sugg};
+use crate::utils::{in_macro, snippet, span_lint_and_sugg};
+use hir::def::{DefKind, Res};
 use if_chain::if_chain;
 use rustc_ast::ast;
+use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_errors::Applicability;
-use rustc_lint::{EarlyContext, EarlyLintPass};
-use rustc_session::{declare_lint_pass, declare_tool_lint};
-use rustc_span::edition::Edition;
+use rustc_hir as hir;
+use rustc_lint::{LateContext, LateLintPass, LintContext};
+use rustc_session::{declare_tool_lint, impl_lint_pass};
+use rustc_span::{edition::Edition, Span};
 
 declare_clippy_lint! {
     /// **What it does:** Checks for `#[macro_use] use...`.
     ///
     /// **Why is this bad?** Since the Rust 2018 edition you can import
     /// macro's directly, this is considered idiomatic.
     ///
-    /// **Known problems:** This lint does not generate an auto-applicable suggestion.
+    /// **Known problems:** None.
     ///
     /// **Example:**
     /// ```rust
@@ -24,29 +27,205 @@ declare_clippy_lint! {
     "#[macro_use] is no longer needed"
 }
 
-declare_lint_pass!(MacroUseImports => [MACRO_USE_IMPORTS]);
+const BRACKETS: &[char] = &['<', '>'];
 
-impl EarlyLintPass for MacroUseImports {
-    fn check_item(&mut self, ecx: &EarlyContext<'_>, item: &ast::Item) {
+#[derive(Clone, Debug, PartialEq, Eq)]
+struct PathAndSpan {
+    path: String,
+    span: Span,
+}
+
+/// `MacroRefData` includes the name of the macro
+/// and the path from `SourceMap::span_to_filename`.
+#[derive(Debug, Clone)]
+pub struct MacroRefData {
+    name: String,
+    path: String,
+}
+
+impl MacroRefData {
+    pub fn new(name: String, callee: Span, cx: &LateContext<'_, '_>) -> Self {
+        let mut path = cx.sess().source_map().span_to_filename(callee).to_string();
+
+        // std lib paths are <::std::module::file type>
+        // so remove brackets, space and type.
+        if path.contains('<') {
+            path = path.replace(BRACKETS, "");
+        }
+        if path.contains(' ') {
+            path = path.split(' ').next().unwrap().to_string();
+        }
+        Self { name, path }
+    }
+}
+
+#[derive(Default)]
+#[allow(clippy::module_name_repetitions)]
+pub struct MacroUseImports {
+    /// the actual import path used and the span of the attribute above it.
+    imports: Vec<(String, Span)>,
+    /// the span of the macro reference, kept to ensure only one reference is used per macro call.
+    collected: FxHashSet<Span>,
+    mac_refs: Vec<MacroRefData>,
+}
+
+impl_lint_pass!(MacroUseImports => [MACRO_USE_IMPORTS]);
+
+impl MacroUseImports {
+    fn push_unique_macro(&mut self, cx: &LateContext<'_, '_>, span: Span) {
+        let call_site = span.source_callsite();
+        let name = snippet(cx, cx.sess().source_map().span_until_char(call_site, '!'), "_");
+        if let Some(callee) = span.source_callee() {
+            if !self.collected.contains(&call_site) {
+                let name = if name.contains("::") {
+                    name.split("::").last().unwrap().to_string()
+                } else {
+                    name.to_string()
+                };
+
+                self.mac_refs.push(MacroRefData::new(name, callee.def_site, cx));
+                self.collected.insert(call_site);
+            }
+        }
+    }
+
+    fn push_unique_macro_pat_ty(&mut self, cx: &LateContext<'_, '_>, span: Span) {
+        let call_site = span.source_callsite();
+        let name = snippet(cx, cx.sess().source_map().span_until_char(call_site, '!'), "_");
+        if let Some(callee) = span.source_callee() {
+            if !self.collected.contains(&call_site) {
+                self.mac_refs
+                    .push(MacroRefData::new(name.to_string(), callee.def_site, cx));
+                self.collected.insert(call_site);
+            }
+        }
+    }
+}
+
+impl<'l, 'txc> LateLintPass<'l, 'txc> for MacroUseImports {
+    fn check_item(&mut self, cx: &LateContext<'_, '_>, item: &hir::Item<'_>) {
         if_chain! {
-            if ecx.sess.opts.edition == Edition::Edition2018;
-            if let ast::ItemKind::Use(use_tree) = &item.kind;
+            if cx.sess().opts.edition == Edition::Edition2018;
+            if let hir::ItemKind::Use(path, _kind) = &item.kind;
             if let Some(mac_attr) = item
                 .attrs
                 .iter()
                 .find(|attr| attr.ident().map(|s| s.to_string()) == Some("macro_use".to_string()));
+            if let Res::Def(DefKind::Mod, id) = path.res;
             then {
-                let msg = "`macro_use` attributes are no longer needed in the Rust 2018 edition";
-                let help = format!("use {}::<macro name>", snippet(ecx, use_tree.span, "_"));
+                for kid in cx.tcx.item_children(id).iter() {
+                    if let Res::Def(DefKind::Macro(_mac_type), mac_id) = kid.res {
+                        let span = mac_attr.span;
+                        let def_path = cx.tcx.def_path_str(mac_id);
+                        self.imports.push((def_path, span));
+                    }
+                }
+            } else {
+                if in_macro(item.span) {
+                    self.push_unique_macro_pat_ty(cx, item.span);
+                }
+            }
+        }
+    }
+    fn check_attribute(&mut self, cx: &LateContext<'_, '_>, attr: &ast::Attribute) {
+        if in_macro(attr.span) {
+            self.push_unique_macro(cx, attr.span);
+        }
+    }
+    fn check_expr(&mut self, cx: &LateContext<'_, '_>, expr: &hir::Expr<'_>) {
+        if in_macro(expr.span) {
+            self.push_unique_macro(cx, expr.span);
+        }
+    }
+    fn check_stmt(&mut self, cx: &LateContext<'_, '_>, stmt: &hir::Stmt<'_>) {
+        if in_macro(stmt.span) {
+            self.push_unique_macro(cx, stmt.span);
+        }
+    }
+    fn check_pat(&mut self, cx: &LateContext<'_, '_>, pat: &hir::Pat<'_>) {
+        if in_macro(pat.span) {
+            self.push_unique_macro_pat_ty(cx, pat.span);
+        }
+    }
+    fn check_ty(&mut self, cx: &LateContext<'_, '_>, ty: &hir::Ty<'_>) {
+        if in_macro(ty.span) {
+            self.push_unique_macro_pat_ty(cx, ty.span);
+        }
+    }
+    #[allow(clippy::too_many_lines)]
+    fn check_crate_post(&mut self, cx: &LateContext<'_, '_>, _krate: &hir::Crate<'_>) {
+        let mut used = FxHashMap::default();
+        let mut check_dup = vec![];
+        for (import, span) in &self.imports {
+            let found_idx = self.mac_refs.iter().position(|mac| import.ends_with(&mac.name));
+
+            if let Some(idx) = found_idx {
+                let _ = self.mac_refs.remove(idx);
+                let seg = import.split("::").collect::<Vec<_>>();
+
+                match seg.as_slice() {
+                    // an empty path is impossible
+                    // a path should always consist of 2 or more segments
+                    [] | [_] => return,
+                    [root, item] => {
+                        if !check_dup.contains(&(*item).to_string()) {
+                            used.entry(((*root).to_string(), span))
+                                .or_insert_with(Vec::new)
+                                .push((*item).to_string());
+                            check_dup.push((*item).to_string());
+                        }
+                    },
+                    [root, rest @ ..] => {
+                        if rest.iter().all(|item| !check_dup.contains(&(*item).to_string())) {
+                            let filtered = rest
+                                .iter()
+                                .filter_map(|item| {
+                                    if check_dup.contains(&(*item).to_string()) {
+                                        None
+                                    } else {
+                                        Some((*item).to_string())
+                                    }
+                                })
+                                .collect::<Vec<_>>();
+                            used.entry(((*root).to_string(), span))
+                                .or_insert_with(Vec::new)
+                                .push(filtered.join("::"));
+                            check_dup.extend(filtered);
+                        } else {
+                            let rest = rest.to_vec();
+                            used.entry(((*root).to_string(), span))
+                                .or_insert_with(Vec::new)
+                                .push(rest.join("::"));
+                            check_dup.extend(rest.iter().map(ToString::to_string));
+                        }
+                    },
+                }
+            }
+        }
+
+        let mut suggestions = vec![];
+        for ((root, span), path) in used {
+            if path.len() == 1 {
+                suggestions.push((span, format!("{}::{}", root, path[0])))
+            } else {
+                suggestions.push((span, format!("{}::{{{}}}", root, path.join(", "))))
+            }
+        }
+
+        // If mac_refs is not empty we have encountered an import we could not handle
+        // such as `std::prelude::v1::foo` or some other macro that expands to an import.
+        if self.mac_refs.is_empty() {
+            for (span, import) in suggestions {
+                let help = format!("use {};", import);
                 span_lint_and_sugg(
-                    ecx,
+                    cx,
                     MACRO_USE_IMPORTS,
-                    mac_attr.span,
-                    msg,
+                    *span,
+                    "`macro_use` attributes are no longer needed in the Rust 2018 edition",
                     "remove the attribute and import the macro directly, try",
                     help,
-                    Applicability::HasPlaceholders,
-                );
+                    Applicability::MaybeIncorrect,
+                )
             }
         }
     }

tests/ui/auxiliary/macro_use_helper.rs

@@ -0,0 +1,60 @@
+extern crate macro_rules;
+
+// STMT
+#[macro_export]
+macro_rules! pub_macro {
+    () => {
+        let _ = "hello Mr. Vonnegut";
+    };
+}
+
+pub mod inner {
+    pub use super::*;
+
+    // RE-EXPORT
+    // this will stick in `inner` module
+    pub use macro_rules::foofoo;
+    pub use macro_rules::try_err;
+
+    pub mod nested {
+        pub use macro_rules::string_add;
+    }
+
+    // ITEM
+    #[macro_export]
+    macro_rules! inner_mod_macro {
+        () => {
+            #[allow(dead_code)]
+            pub struct Tardis;
+        };
+    }
+}
+
+// EXPR
+#[macro_export]
+macro_rules! function_macro {
+    () => {
+        if true {
+        } else {
+        }
+    };
+}
+
+// TYPE
+#[macro_export]
+macro_rules! ty_macro {
+    () => {
+        Vec<u8>
+    };
+}
+
+mod extern_exports {
+    pub(super) mod private_inner {
+        #[macro_export]
+        macro_rules! pub_in_private_macro {
+            ($name:ident) => {
+                let $name = String::from("secrets and lies");
+            };
+        }
+    }
+}

tests/ui/macro_use_imports.fixed

@@ -0,0 +1,43 @@
+// compile-flags: --edition 2018
+// aux-build:macro_rules.rs
+// aux-build:macro_use_helper.rs
+// run-rustfix
+// ignore-32bit
+
+#![allow(unused_imports, unreachable_code, unused_variables, dead_code)]
+#![allow(clippy::single_component_path_imports)]
+#![warn(clippy::macro_use_imports)]
+
+#[macro_use]
+extern crate macro_use_helper as mac;
+
+#[macro_use]
+extern crate clippy_mini_macro_test as mini_mac;
+
+mod a {
+    use mac::{pub_macro, inner_mod_macro, function_macro, ty_macro, pub_in_private_macro};
+    use mac;
+    use mini_mac::ClippyMiniMacroTest;
+    use mini_mac;
+    use mac::{inner::foofoo, inner::try_err};
+    use mac::inner;
+    use mac::inner::nested::string_add;
+    use mac::inner::nested;
+
+    #[derive(ClippyMiniMacroTest)]
+    struct Test;
+
+    fn test() {
+        pub_macro!();
+        inner_mod_macro!();
+        pub_in_private_macro!(_var);
+        function_macro!();
+        let v: ty_macro!() = Vec::default();
+
+        inner::try_err!();
+        inner::foofoo!();
+        nested::string_add!();
+    }
+}
+
+fn main() {}