Improve `implicit_return`

[rust.git] / clippy_lints / src / collapsible_if.rs

diff --git a/clippy_lints/src/collapsible_if.rs b/clippy_lints/src/collapsible_if.rs
index 25fb773a6d674a3b33f4bc6a6ed1f68b501c7fd8..dae5c86bd4437b28c9025b399214351b15a99d8e 100644 (file)
--- a/clippy_lints/src/collapsible_if.rs
+++ b/clippy_lints/src/collapsible_if.rs
@@ -12,20 +12,18 @@
 //!
 //! This lint is **warn** by default
 
+use clippy_utils::diagnostics::{span_lint_and_sugg, span_lint_and_then};
+use clippy_utils::source::{snippet_block, snippet_block_with_applicability};
+use clippy_utils::sugg::Sugg;
 use if_chain::if_chain;
 use rustc_ast::ast;
+use rustc_errors::Applicability;
 use rustc_lint::{EarlyContext, EarlyLintPass};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 
-use crate::utils::sugg::Sugg;
-use crate::utils::{snippet_block, snippet_block_with_applicability, span_lint_and_sugg, span_lint_and_then};
-use rustc_errors::Applicability;
-
 declare_clippy_lint! {
     /// **What it does:** Checks for nested `if` statements which can be collapsed
-    /// by `&&`-combining their conditions and for `else { if ... }` expressions
-    /// that
-    /// can be collapsed to `else if ...`.
+    /// by `&&`-combining their conditions.
     ///
     /// **Why is this bad?** Each `if`-statement adds one level of nesting, which
     /// makes code look more complex than it really is.
@@ -40,7 +38,31 @@
     ///     }
     /// }
     ///
-    /// // or
+    /// ```
+    ///
+    /// Should be written:
+    ///
+    /// ```rust.ignore
+    /// if x && y {
+    ///     …
+    /// }
+    /// ```
+    pub COLLAPSIBLE_IF,
+    style,
+    "nested `if`s that can be collapsed (e.g., `if x { if y { ... } }`"
+}
+
+declare_clippy_lint! {
+    /// **What it does:** Checks for collapsible `else { if ... }` expressions
+    /// that can be collapsed to `else if ...`.
+    ///
+    /// **Why is this bad?** Each `if`-statement adds one level of nesting, which
+    /// makes code look more complex than it really is.
+    ///
+    /// **Known problems:** None.
+    ///
+    /// **Example:**
+    /// ```rust,ignore
     ///
     /// if x {
     ///     …
@@ -54,24 +76,18 @@
     /// Should be written:
     ///
     /// ```rust.ignore
-    /// if x && y {
-    ///     …
-    /// }
-    ///
-    /// // or
-    ///
     /// if x {
     ///     …
     /// } else if y {
     ///     …
     /// }
     /// ```
-    pub COLLAPSIBLE_IF,
+    pub COLLAPSIBLE_ELSE_IF,
     style,
-    "`if`s that can be collapsed (e.g., `if x { if y { ... } }` and `else { if x { ... } }`)"
+    "nested `else`-`if` expressions that can be collapsed (e.g., `else { if x { ... } }`)"
 }
 
-declare_lint_pass!(CollapsibleIf => [COLLAPSIBLE_IF]);
+declare_lint_pass!(CollapsibleIf => [COLLAPSIBLE_IF, COLLAPSIBLE_ELSE_IF]);
 
 impl EarlyLintPass for CollapsibleIf {
     fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &ast::Expr) {
@@ -106,16 +122,17 @@ fn check_collapsible_maybe_if_let(cx: &EarlyContext<'_>, else_: &ast::Expr) {
         if let ast::ExprKind::Block(ref block, _) = else_.kind;
         if !block_starts_with_comment(cx, block);
         if let Some(else_) = expr_block(block);
+        if else_.attrs.is_empty();
         if !else_.span.from_expansion();
         if let ast::ExprKind::If(..) = else_.kind;
         then {
             let mut applicability = Applicability::MachineApplicable;
             span_lint_and_sugg(
                 cx,
-                COLLAPSIBLE_IF,
+                COLLAPSIBLE_ELSE_IF,
                 block.span,
                 "this `else { if .. }` block can be collapsed",
-                "try",
+                "collapse nested if block",
                 snippet_block_with_applicability(cx, else_.span, "..", Some(block.span), &mut applicability).into_owned(),
                 applicability,
             );
@@ -127,22 +144,18 @@ fn check_collapsible_no_if_let(cx: &EarlyContext<'_>, expr: &ast::Expr, check: &
     if_chain! {
         if !block_starts_with_comment(cx, then);
         if let Some(inner) = expr_block(then);
+        if inner.attrs.is_empty();
         if let ast::ExprKind::If(ref check_inner, ref content, None) = inner.kind;
+        // Prevent triggering on `if c { if let a = b { .. } }`.
+        if !matches!(check_inner.kind, ast::ExprKind::Let(..));
+        if expr.span.ctxt() == inner.span.ctxt();
         then {
-            if let ast::ExprKind::Let(..) = check_inner.kind {
-                // Prevent triggering on `if c { if let a = b { .. } }`.
-                return;
-            }
-
-            if expr.span.ctxt() != inner.span.ctxt() {
-                return;
-            }
-            span_lint_and_then(cx, COLLAPSIBLE_IF, expr.span, "this `if` statement can be collapsed", |db| {
+            span_lint_and_then(cx, COLLAPSIBLE_IF, expr.span, "this `if` statement can be collapsed", |diag| {
                 let lhs = Sugg::ast(cx, check, "..");
                 let rhs = Sugg::ast(cx, check_inner, "..");
-                db.span_suggestion(
+                diag.span_suggestion(
                     expr.span,
-                    "try",
+                    "collapse nested if block",
                     format!(
                         "if {} {}",
                         lhs.and(&rhs),