]> git.lizzy.rs Git - rust.git/blobdiff - clippy_lints/src/returns.rs
rustup https://github.com/rust-lang/rust/pull/67455
[rust.git] / clippy_lints / src / returns.rs
index caeb1e8b9fbb6d114ca451b6f236a4129d5c04f6..c3afa156017d21dce3803aa2c0f61d6db568e434 100644 (file)
@@ -1,13 +1,14 @@
 use if_chain::if_chain;
+use rustc::declare_lint_pass;
 use rustc::lint::{in_external_macro, EarlyContext, EarlyLintPass, LintArray, LintContext, LintPass};
-use rustc::{declare_lint_pass, declare_tool_lint};
 use rustc_errors::Applicability;
+use rustc_session::declare_tool_lint;
 use syntax::ast;
 use syntax::source_map::Span;
 use syntax::visit::FnKind;
 use syntax_pos::BytePos;
 
-use crate::utils::{in_macro_or_desugar, match_path_ast, snippet_opt, span_lint_and_then};
+use crate::utils::{match_path_ast, snippet_opt, span_lint_and_then};
 
 declare_clippy_lint! {
     /// **What it does:** Checks for return statements at the end of a block.
@@ -86,7 +87,7 @@
 #[derive(PartialEq, Eq, Copy, Clone)]
 enum RetReplacement {
     Empty,
-    Unit
+    Block,
 }
 
 declare_lint_pass!(Return => [NEEDLESS_RETURN, LET_AND_RETURN, UNUSED_UNIT]);
@@ -95,7 +96,7 @@ impl Return {
     // Check the final stmt or expr in a block for unnecessary return.
     fn check_block_return(&mut self, cx: &EarlyContext<'_>, block: &ast::Block) {
         if let Some(stmt) = block.stmts.last() {
-            match stmt.node {
+            match stmt.kind {
                 ast::StmtKind::Expr(ref expr) | ast::StmtKind::Semi(ref expr) => {
                     self.check_final_expr(cx, expr, Some(stmt.span), RetReplacement::Empty);
                 },
@@ -105,13 +106,24 @@ fn check_block_return(&mut self, cx: &EarlyContext<'_>, block: &ast::Block) {
     }
 
     // Check a the final expression in a block if it's a return.
-    fn check_final_expr(&mut self, cx: &EarlyContext<'_>, expr: &ast::Expr, span: Option<Span>, replacement: RetReplacement) {
-        match expr.node {
+    fn check_final_expr(
+        &mut self,
+        cx: &EarlyContext<'_>,
+        expr: &ast::Expr,
+        span: Option<Span>,
+        replacement: RetReplacement,
+    ) {
+        match expr.kind {
             // simple return is always "bad"
             ast::ExprKind::Ret(ref inner) => {
                 // allow `#[cfg(a)] return a; #[cfg(b)] return b;`
                 if !expr.attrs.iter().any(attr_is_cfg) {
-                    self.emit_return_lint(cx, span.expect("`else return` is not possible"), inner.as_ref().map(|i| i.span), replacement);
+                    Self::emit_return_lint(
+                        cx,
+                        span.expect("`else return` is not possible"),
+                        inner.as_ref().map(|i| i.span),
+                        replacement,
+                    );
                 }
             },
             // a whole block? check it!
@@ -128,76 +140,71 @@ fn check_final_expr(&mut self, cx: &EarlyContext<'_>, expr: &ast::Expr, span: Op
             // a match expr, check all arms
             ast::ExprKind::Match(_, ref arms) => {
                 for arm in arms {
-                    self.check_final_expr(cx, &arm.body, Some(arm.body.span), RetReplacement::Unit);
+                    self.check_final_expr(cx, &arm.body, Some(arm.body.span), RetReplacement::Block);
                 }
             },
             _ => (),
         }
     }
 
-    fn emit_return_lint(&mut self, cx: &EarlyContext<'_>, ret_span: Span, inner_span: Option<Span>, replacement: RetReplacement) {
+    fn emit_return_lint(cx: &EarlyContext<'_>, ret_span: Span, inner_span: Option<Span>, replacement: RetReplacement) {
         match inner_span {
             Some(inner_span) => {
-                if in_external_macro(cx.sess(), inner_span) || in_macro_or_desugar(inner_span) {
+                if in_external_macro(cx.sess(), inner_span) || inner_span.from_expansion() {
                     return;
                 }
 
                 span_lint_and_then(cx, NEEDLESS_RETURN, ret_span, "unneeded return statement", |db| {
                     if let Some(snippet) = snippet_opt(cx, inner_span) {
+                        db.span_suggestion(ret_span, "remove `return`", snippet, Applicability::MachineApplicable);
+                    }
+                })
+            },
+            None => match replacement {
+                RetReplacement::Empty => {
+                    span_lint_and_then(cx, NEEDLESS_RETURN, ret_span, "unneeded return statement", |db| {
                         db.span_suggestion(
                             ret_span,
-                            "remove `return` as shown",
-                            snippet,
+                            "remove `return`",
+                            String::new(),
                             Applicability::MachineApplicable,
                         );
-                    }
-                })
+                    });
+                },
+                RetReplacement::Block => {
+                    span_lint_and_then(cx, NEEDLESS_RETURN, ret_span, "unneeded return statement", |db| {
+                        db.span_suggestion(
+                            ret_span,
+                            "replace `return` with an empty block",
+                            "{}".to_string(),
+                            Applicability::MachineApplicable,
+                        );
+                    });
+                },
             },
-            None => {
-                match replacement {
-                    RetReplacement::Empty => {
-                        span_lint_and_then(cx, NEEDLESS_RETURN, ret_span, "unneeded return statement", |db| {
-                            db.span_suggestion(
-                                ret_span,
-                                "remove `return`",
-                                String::new(),
-                                Applicability::MachineApplicable,
-                            );
-                        });
-                    }
-                    RetReplacement::Unit => {
-                        span_lint_and_then(cx, NEEDLESS_RETURN, ret_span, "unneeded return statement", |db| {
-                            db.span_suggestion(
-                                ret_span,
-                                "replace `return` with the unit type `()`",
-                                "()".to_string(),
-                                Applicability::MachineApplicable,
-                            );
-                        });
-                    }
-                }
-            }
         }
     }
 
     // Check for "let x = EXPR; x"
-    fn check_let_return(&mut self, cx: &EarlyContext<'_>, block: &ast::Block) {
+    fn check_let_return(cx: &EarlyContext<'_>, block: &ast::Block) {
         let mut it = block.stmts.iter();
 
         // we need both a let-binding stmt and an expr
         if_chain! {
             if let Some(retexpr) = it.next_back();
-            if let ast::StmtKind::Expr(ref retexpr) = retexpr.node;
+            if let ast::StmtKind::Expr(ref retexpr) = retexpr.kind;
             if let Some(stmt) = it.next_back();
-            if let ast::StmtKind::Local(ref local) = stmt.node;
+            if let ast::StmtKind::Local(ref local) = stmt.kind;
             // don't lint in the presence of type inference
             if local.ty.is_none();
             if local.attrs.is_empty();
             if let Some(ref initexpr) = local.init;
-            if let ast::PatKind::Ident(_, ident, _) = local.pat.node;
-            if let ast::ExprKind::Path(_, ref path) = retexpr.node;
+            if let ast::PatKind::Ident(_, ident, _) = local.pat.kind;
+            if let ast::ExprKind::Path(_, ref path) = retexpr.kind;
             if match_path_ast(path, &[&*ident.name.as_str()]);
             if !in_external_macro(cx.sess(), initexpr.span);
+            if !in_external_macro(cx.sess(), retexpr.span);
+            if !in_external_macro(cx.sess(), local.span);
             then {
                 span_lint_and_then(
                     cx,
@@ -234,8 +241,8 @@ fn check_fn(&mut self, cx: &EarlyContext<'_>, kind: FnKind<'_>, decl: &ast::FnDe
         }
         if_chain! {
             if let ast::FunctionRetTy::Ty(ref ty) = decl.output;
-            if let ast::TyKind::Tup(ref vals) = ty.node;
-            if vals.is_empty() && !in_macro_or_desugar(ty.span) && get_def(span) == get_def(ty.span);
+            if let ast::TyKind::Tup(ref vals) = ty.kind;
+            if vals.is_empty() && !ty.span.from_expansion() && get_def(span) == get_def(ty.span);
             then {
                 let (rspan, appl) = if let Ok(fn_source) =
                         cx.sess().source_map()
@@ -263,11 +270,11 @@ fn check_fn(&mut self, cx: &EarlyContext<'_>, kind: FnKind<'_>, decl: &ast::FnDe
     }
 
     fn check_block(&mut self, cx: &EarlyContext<'_>, block: &ast::Block) {
-        self.check_let_return(cx, block);
+        Self::check_let_return(cx, block);
         if_chain! {
             if let Some(ref stmt) = block.stmts.last();
-            if let ast::StmtKind::Expr(ref expr) = stmt.node;
-            if is_unit_expr(expr) && !in_macro_or_desugar(expr.span);
+            if let ast::StmtKind::Expr(ref expr) = stmt.kind;
+            if is_unit_expr(expr) && !stmt.span.from_expansion();
             then {
                 let sp = expr.span;
                 span_lint_and_then(cx, UNUSED_UNIT, sp, "unneeded unit expression", |db| {
@@ -283,9 +290,9 @@ fn check_block(&mut self, cx: &EarlyContext<'_>, block: &ast::Block) {
     }
 
     fn check_expr(&mut self, cx: &EarlyContext<'_>, e: &ast::Expr) {
-        match e.node {
+        match e.kind {
             ast::ExprKind::Ret(Some(ref expr)) | ast::ExprKind::Break(_, Some(ref expr)) => {
-                if is_unit_expr(expr) && !in_macro_or_desugar(expr.span) {
+                if is_unit_expr(expr) && !expr.span.from_expansion() {
                     span_lint_and_then(cx, UNUSED_UNIT, expr.span, "unneeded `()`", |db| {
                         db.span_suggestion(
                             expr.span,
@@ -306,13 +313,18 @@ fn attr_is_cfg(attr: &ast::Attribute) -> bool {
 }
 
 // get the def site
+#[must_use]
 fn get_def(span: Span) -> Option<Span> {
-    span.ctxt().outer_expn_info().and_then(|info| info.def_site)
+    if span.from_expansion() {
+        Some(span.ctxt().outer_expn_data().def_site)
+    } else {
+        None
+    }
 }
 
 // is this expr a `()` unit?
 fn is_unit_expr(expr: &ast::Expr) -> bool {
-    if let ast::ExprKind::Tup(ref vals) = expr.node {
+    if let ast::ExprKind::Tup(ref vals) = expr.kind {
         vals.is_empty()
     } else {
         false