X-Git-Url: https://git.lizzy.rs/?a=blobdiff_plain;f=clippy_lints%2Fsrc%2Fsingle_component_path_imports.rs;h=1eaad438237ec16f4831806b7f5588e527cc151e;hb=ebf88c9734246a790305f6faaba0bf8e3f150dff;hp=5a9bc73fe42b2d78b0b3abcef2cfeecf31fd78c7;hpb=09165ff5761bb1f397e37ee2d32d96adf7afdd86;p=rust.git

diff --git a/clippy_lints/src/single_component_path_imports.rs b/clippy_lints/src/single_component_path_imports.rs
index 5a9bc73fe42..1eaad438237 100644
--- a/clippy_lints/src/single_component_path_imports.rs
+++ b/clippy_lints/src/single_component_path_imports.rs
@@ -1,10 +1,10 @@
-use crate::utils::{in_macro, span_lint_and_sugg};
-use if_chain::if_chain;
+use clippy_utils::diagnostics::{span_lint_and_help, span_lint_and_sugg};
+use clippy_utils::in_macro;
+use rustc_ast::{ptr::P, Crate, Item, ItemKind, MacroDef, ModKind, UseTreeKind, VisibilityKind};
 use rustc_errors::Applicability;
 use rustc_lint::{EarlyContext, EarlyLintPass};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
-use rustc_span::edition::Edition;
-use syntax::ast::{Item, ItemKind, UseTreeKind};
+use rustc_span::{edition::Edition, symbol::kw, Span, Symbol};
 
 declare_clippy_lint! {
     /// **What it does:** Checking for imports with single component use path.
@@ -16,7 +16,7 @@
     ///
     /// **Example:**
     ///
-    /// ```rust, ignore
+    /// ```rust,ignore
     /// use regex;
     ///
     /// fn main() {
@@ -24,7 +24,7 @@
     /// }
     /// ```
     /// Better as
-    /// ```rust, ignore
+    /// ```rust,ignore
     /// fn main() {
     ///     regex::Regex::new(r"^\d{4}-\d{2}-\d{2}$").unwrap();
     /// }
@@ -37,26 +37,144 @@
 declare_lint_pass!(SingleComponentPathImports => [SINGLE_COMPONENT_PATH_IMPORTS]);
 
 impl EarlyLintPass for SingleComponentPathImports {
-    fn check_item(&mut self, cx: &EarlyContext<'_>, item: &Item) {
-        if_chain! {
-            if !in_macro(item.span);
-            if cx.sess.opts.edition == Edition::Edition2018;
-            if !item.vis.node.is_pub();
-            if let ItemKind::Use(use_tree) = &item.kind;
-            if let segments = &use_tree.prefix.segments;
-            if segments.len() == 1;
-            if let UseTreeKind::Simple(None, _, _) = use_tree.kind;
-            then {
+    fn check_crate(&mut self, cx: &EarlyContext<'_>, krate: &Crate) {
+        if cx.sess.opts.edition < Edition::Edition2018 {
+            return;
+        }
+        check_mod(cx, &krate.items);
+    }
+}
+
+fn check_mod(cx: &EarlyContext<'_>, items: &[P<Item>]) {
+    // keep track of imports reused with `self` keyword,
+    // such as `self::crypto_hash` in the example below
+    // ```rust,ignore
+    // use self::crypto_hash::{Algorithm, Hasher};
+    // ```
+    let mut imports_reused_with_self = Vec::new();
+
+    // keep track of single use statements
+    // such as `crypto_hash` in the example below
+    // ```rust,ignore
+    // use crypto_hash;
+    // ```
+    let mut single_use_usages = Vec::new();
+
+    // keep track of macros defined in the module as we don't want it to trigger on this (#7106)
+    // ```rust,ignore
+    // macro_rules! foo { () => {} };
+    // pub(crate) use foo;
+    // ```
+    let mut macros = Vec::new();
+
+    for item in items {
+        track_uses(
+            cx,
+            item,
+            &mut imports_reused_with_self,
+            &mut single_use_usages,
+            &mut macros,
+        );
+    }
+
+    for single_use in &single_use_usages {
+        if !imports_reused_with_self.contains(&single_use.0) {
+            let can_suggest = single_use.2;
+            if can_suggest {
                 span_lint_and_sugg(
                     cx,
                     SINGLE_COMPONENT_PATH_IMPORTS,
-                    item.span,
+                    single_use.1,
                     "this import is redundant",
                     "remove it entirely",
                     String::new(),
-                    Applicability::MachineApplicable
+                    Applicability::MachineApplicable,
+                );
+            } else {
+                span_lint_and_help(
+                    cx,
+                    SINGLE_COMPONENT_PATH_IMPORTS,
+                    single_use.1,
+                    "this import is redundant",
+                    None,
+                    "remove this import",
                 );
             }
         }
     }
 }
+
+fn track_uses(
+    cx: &EarlyContext<'_>,
+    item: &Item,
+    imports_reused_with_self: &mut Vec<Symbol>,
+    single_use_usages: &mut Vec<(Symbol, Span, bool)>,
+    macros: &mut Vec<Symbol>,
+) {
+    if in_macro(item.span) || item.vis.kind.is_pub() {
+        return;
+    }
+
+    match &item.kind {
+        ItemKind::Mod(_, ModKind::Loaded(ref items, ..)) => {
+            check_mod(cx, items);
+        },
+        ItemKind::MacroDef(MacroDef { macro_rules: true, .. }) => {
+            macros.push(item.ident.name);
+        },
+        ItemKind::Use(use_tree) => {
+            let segments = &use_tree.prefix.segments;
+
+            let should_report =
+                |name: &Symbol| !macros.contains(name) || matches!(item.vis.kind, VisibilityKind::Inherited);
+
+            // keep track of `use some_module;` usages
+            if segments.len() == 1 {
+                if let UseTreeKind::Simple(None, _, _) = use_tree.kind {
+                    let name = segments[0].ident.name;
+                    if should_report(&name) {
+                        single_use_usages.push((name, item.span, true));
+                    }
+                }
+                return;
+            }
+
+            if segments.is_empty() {
+                // keep track of `use {some_module, some_other_module};` usages
+                if let UseTreeKind::Nested(trees) = &use_tree.kind {
+                    for tree in trees {
+                        let segments = &tree.0.prefix.segments;
+                        if segments.len() == 1 {
+                            if let UseTreeKind::Simple(None, _, _) = tree.0.kind {
+                                let name = segments[0].ident.name;
+                                if should_report(&name) {
+                                    single_use_usages.push((name, tree.0.span, false));
+                                }
+                            }
+                        }
+                    }
+                }
+            } else {
+                // keep track of `use self::some_module` usages
+                if segments[0].ident.name == kw::SelfLower {
+                    // simple case such as `use self::module::SomeStruct`
+                    if segments.len() > 1 {
+                        imports_reused_with_self.push(segments[1].ident.name);
+                        return;
+                    }
+
+                    // nested case such as `use self::{module1::Struct1, module2::Struct2}`
+                    if let UseTreeKind::Nested(trees) = &use_tree.kind {
+                        for tree in trees {
+                            let segments = &tree.0.prefix.segments;
+                            if !segments.is_empty() {
+                                imports_reused_with_self.push(segments[0].ident.name);
+                            }
+                        }
+                    }
+                }
+            }
+        },
+        _ => {},
+    }
+}