From 16bbd243f9e5c71ff0481c7168a32f4f442c582f Mon Sep 17 00:00:00 2001
From: Cameron Steffen <cam.steffen94@gmail.com>
Date: Wed, 24 Mar 2021 19:17:25 -0500
Subject: [PATCH] Simplify needless_bool

---
 clippy_lints/src/needless_bool.rs | 63 ++++++++++---------------------
 1 file changed, 19 insertions(+), 44 deletions(-)

diff --git a/clippy_lints/src/needless_bool.rs b/clippy_lints/src/needless_bool.rs
index e780943625272..d391fbecf82e1 100644
--- a/clippy_lints/src/needless_bool.rs
+++ b/clippy_lints/src/needless_bool.rs
@@ -6,10 +6,10 @@ use clippy_utils::diagnostics::{span_lint, span_lint_and_sugg};
 use clippy_utils::higher;
 use clippy_utils::source::snippet_with_applicability;
 use clippy_utils::sugg::Sugg;
-use clippy_utils::{get_parent_node, is_else_clause, is_expn_of};
+use clippy_utils::{get_parent_node, is_else_clause, is_expn_of, peel_blocks, peel_blocks_with_stmt};
 use rustc_ast::ast::LitKind;
 use rustc_errors::Applicability;
-use rustc_hir::{BinOpKind, Block, Expr, ExprKind, HirId, Node, StmtKind, UnOp};
+use rustc_hir::{BinOpKind, Block, Expr, ExprKind, HirId, Node, UnOp};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::source_map::Spanned;
@@ -143,8 +143,8 @@ impl<'tcx> LateLintPass<'tcx> for NeedlessBool {
                     applicability,
                 );
             };
-            if let ExprKind::Block(then, _) = then.kind {
-                match (fetch_bool_block(then), fetch_bool_expr(r#else)) {
+            if let Some((a, b)) = fetch_bool_block(then).and_then(|a| Some((a, fetch_bool_block(r#else)?))) {
+                match (a, b) {
                     (RetBool(true), RetBool(true)) | (Bool(true), Bool(true)) => {
                         span_lint(
                             cx,
@@ -167,8 +167,6 @@ impl<'tcx> LateLintPass<'tcx> for NeedlessBool {
                     (Bool(false), Bool(true)) => reduce(false, true),
                     _ => (),
                 }
-            } else {
-                panic!("IfExpr `then` node is not an `ExprKind::Block`");
             }
         }
     }
@@ -271,8 +269,6 @@ fn check_comparison<'a, 'tcx>(
     right_false: Option<(impl FnOnce(Sugg<'a>) -> Sugg<'a>, &str)>,
     no_literal: Option<(impl FnOnce(Sugg<'a>, Sugg<'a>) -> Sugg<'a>, &str)>,
 ) {
-    use self::Expression::{Bool, Other};
-
     if let ExprKind::Binary(op, left_side, right_side) = e.kind {
         let (l_ty, r_ty) = (
             cx.typeck_results().expr_ty(left_side),
@@ -304,19 +300,19 @@ fn check_comparison<'a, 'tcx>(
             }
 
             match (fetch_bool_expr(left_side), fetch_bool_expr(right_side)) {
-                (Bool(true), Other) => left_true.map_or((), |(h, m)| {
+                (Some(true), None) => left_true.map_or((), |(h, m)| {
                     suggest_bool_comparison(cx, e, right_side, applicability, m, h);
                 }),
-                (Other, Bool(true)) => right_true.map_or((), |(h, m)| {
+                (None, Some(true)) => right_true.map_or((), |(h, m)| {
                     suggest_bool_comparison(cx, e, left_side, applicability, m, h);
                 }),
-                (Bool(false), Other) => left_false.map_or((), |(h, m)| {
+                (Some(false), None) => left_false.map_or((), |(h, m)| {
                     suggest_bool_comparison(cx, e, right_side, applicability, m, h);
                 }),
-                (Other, Bool(false)) => right_false.map_or((), |(h, m)| {
+                (None, Some(false)) => right_false.map_or((), |(h, m)| {
                     suggest_bool_comparison(cx, e, left_side, applicability, m, h);
                 }),
-                (Other, Other) => no_literal.map_or((), |(h, m)| {
+                (None, None) => no_literal.map_or((), |(h, m)| {
                     let left_side = Sugg::hir_with_applicability(cx, left_side, "..", &mut applicability);
                     let right_side = Sugg::hir_with_applicability(cx, right_side, "..", &mut applicability);
                     span_lint_and_sugg(
@@ -365,41 +361,20 @@ fn suggest_bool_comparison<'a, 'tcx>(
 enum Expression {
     Bool(bool),
     RetBool(bool),
-    Other,
 }
 
-fn fetch_bool_block(block: &Block<'_>) -> Expression {
-    match (&*block.stmts, block.expr.as_ref()) {
-        (&[], Some(e)) => fetch_bool_expr(&**e),
-        (&[ref e], None) => {
-            if let StmtKind::Semi(e) = e.kind {
-                if let ExprKind::Ret(_) = e.kind {
-                    fetch_bool_expr(e)
-                } else {
-                    Expression::Other
-                }
-            } else {
-                Expression::Other
-            }
-        },
-        _ => Expression::Other,
+fn fetch_bool_block(expr: &Expr<'_>) -> Option<Expression> {
+    match peel_blocks_with_stmt(expr).kind {
+        ExprKind::Ret(Some(ret)) => Some(Expression::RetBool(fetch_bool_expr(ret)?)),
+        _ => Some(Expression::Bool(fetch_bool_expr(expr)?)),
     }
 }
 
-fn fetch_bool_expr(expr: &Expr<'_>) -> Expression {
-    match expr.kind {
-        ExprKind::Block(block, _) => fetch_bool_block(block),
-        ExprKind::Lit(ref lit_ptr) => {
-            if let LitKind::Bool(value) = lit_ptr.node {
-                Expression::Bool(value)
-            } else {
-                Expression::Other
-            }
-        },
-        ExprKind::Ret(Some(expr)) => match fetch_bool_expr(expr) {
-            Expression::Bool(value) => Expression::RetBool(value),
-            _ => Expression::Other,
-        },
-        _ => Expression::Other,
+fn fetch_bool_expr(expr: &Expr<'_>) -> Option<bool> {
+    if let ExprKind::Lit(ref lit_ptr) = peel_blocks(expr).kind {
+        if let LitKind::Bool(value) = lit_ptr.node {
+            return Some(value);
+        }
     }
+    None
 }