Add ifs_as_logical_ops lint

CHANGELOG.md

@@ -5838,6 +5838,7 @@ Released 2018-09-13
 [`if_not_else`]: https://rust-lang.github.io/rust-clippy/master/index.html#if_not_else
 [`if_same_then_else`]: https://rust-lang.github.io/rust-clippy/master/index.html#if_same_then_else
 [`if_then_some_else_none`]: https://rust-lang.github.io/rust-clippy/master/index.html#if_then_some_else_none
+[`ifs_as_logical_ops`]: https://rust-lang.github.io/rust-clippy/master/index.html#ifs_as_logical_ops
 [`ifs_same_cond`]: https://rust-lang.github.io/rust-clippy/master/index.html#ifs_same_cond
 [`ignore_without_reason`]: https://rust-lang.github.io/rust-clippy/master/index.html#ignore_without_reason
 [`ignored_unit_patterns`]: https://rust-lang.github.io/rust-clippy/master/index.html#ignored_unit_patterns

clippy_lints/src/declared_lints.rs

@@ -198,6 +198,7 @@ pub static LINTS: &[&crate::LintInfo] = &[
     crate::if_let_mutex::IF_LET_MUTEX_INFO,
     crate::if_not_else::IF_NOT_ELSE_INFO,
     crate::if_then_some_else_none::IF_THEN_SOME_ELSE_NONE_INFO,
+    crate::ifs_as_logical_ops::IFS_AS_LOGICAL_OPS_INFO,
     crate::ignored_unit_patterns::IGNORED_UNIT_PATTERNS_INFO,
     crate::impl_hash_with_borrow_str_and_bytes::IMPL_HASH_BORROW_WITH_STR_AND_BYTES_INFO,
     crate::implicit_hasher::IMPLICIT_HASHER_INFO,

clippy_lints/src/ifs_as_logical_ops.rs

@@ -0,0 +1,67 @@
+use clippy_utils::diagnostics::span_lint_and_sugg;
+use clippy_utils::is_never_expr;
+use clippy_utils::source::SpanRangeExt;
+use clippy_utils::sym::clippy_utils;
+use rustc_ast::LitKind;
+use rustc_errors::Applicability;
+use rustc_hir::*;
+use rustc_lint::{LateContext, LateLintPass};
+use rustc_session::declare_lint_pass;
+
+declare_clippy_lint! {
+    /// ### What it does
+    ///
+    /// ### Why is this bad?
+    ///
+    /// ### Example
+    /// ```no_run
+    /// // example code where clippy issues a warning
+    /// ```
+    /// Use instead:
+    /// ```no_run
+    /// // example code which does not raise clippy warning
+    /// ```
+    #[clippy::version = "1.89.0"]
+    pub IFS_AS_LOGICAL_OPS,
+    nursery,
+    "default lint description"
+}
+declare_lint_pass!(IfsAsLogicalOps => [IFS_AS_LOGICAL_OPS]);
+
+impl<'tcx> LateLintPass<'tcx> for IfsAsLogicalOps {
+    fn check_expr(&mut self, cx: &LateContext<'tcx>, e: &'tcx Expr<'tcx>) {
+        if let ExprKind::If(cond, cond_inner, Some(els)) = e.kind
+            && let ExprKind::Block(if_block, _label) = cond_inner.kind
+            // Check if the if-block has only a return statement
+            && if_block.stmts.len() == 0
+            && let Some(if_expr) = if_block.expr
+            // and does not diverge.
+            && is_never_expr(cx, if_expr).is_none()
+            // And that the else block consists of only the boolean 'false'.
+            && let ExprKind::Block(else_block, _label) = els.kind
+            && else_block.stmts.len() == 0
+            && let Some(else_expr) = else_block.expr
+            && let ExprKind::Lit(lit) = else_expr.kind
+            && let LitKind::Bool(value) = lit.node
+            && value == false
+        {
+            let maybe_lhs_snippet = if_expr.span.get_source_text(cx);
+            let maybe_rhs_snippet = lit.span.get_source_text(cx);
+            if let Some(lhs_snippet) = maybe_lhs_snippet
+                && let Some(rhs_snippet) = maybe_rhs_snippet
+            {
+                let lhs_text = lhs_snippet.as_str();
+                let rhs_text = rhs_snippet.as_str();
+                span_lint_and_sugg(
+                    cx,
+                    IFS_AS_LOGICAL_OPS,
+                    e.span,
+                    "Logical operations are clearer than if conditions in this instance",
+                    "try",
+                    format!("{lhs_text} && {rhs_text}"),
+                    Applicability::MachineApplicable,
+                );
+            }
+        }
+    }
+}

clippy_lints/src/lib.rs

@@ -157,6 +157,7 @@ mod future_not_send;
 mod if_let_mutex;
 mod if_not_else;
 mod if_then_some_else_none;
+mod ifs_as_logical_ops;
 mod ignored_unit_patterns;
 mod impl_hash_with_borrow_str_and_bytes;
 mod implicit_hasher;
@@ -948,5 +949,6 @@ pub fn register_lints(store: &mut rustc_lint::LintStore, conf: &'static Conf) {
     store.register_late_pass(move |_| Box::new(redundant_test_prefix::RedundantTestPrefix));
     store.register_late_pass(|_| Box::new(cloned_ref_to_slice_refs::ClonedRefToSliceRefs::new(conf)));
     store.register_late_pass(|_| Box::new(infallible_try_from::InfallibleTryFrom));
+    store.register_late_pass(|_| Box::new(ifs_as_logical_ops::IfsAsLogicalOps));
     // add lints here, do not remove this comment, it's used in `new_lint`
 }

output.txt

@@ -0,0 +1,23 @@
+    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.03s
+     Running `target/debug/clippy_dev lint /Users/barun511/open_source/clippy-examples/src/main.rs`
+   Compiling clippy_lints v0.1.89 (/Users/barun511/open_source/rust-clippy/clippy_lints)
+warning: unused import: `clippy_utils::sym::clippy_utils`
+ --> clippy_lints/src/ifs_as_logical_ops.rs:3:5
+  |
+3 | use clippy_utils::sym::clippy_utils;
+  |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+  |
+  = note: `#[warn(unused_imports)]` on by default
+
+warning: unused variable: `cond`
+  --> clippy_lints/src/ifs_as_logical_ops.rs:31:29
+   |
+31 |         if let ExprKind::If(cond, cond_inner, Some(els)) = e.kind
+   |                             ^^^^ help: if this is intentional, prefix it with an underscore: `_cond`
+   |
+   = note: `#[warn(unused_variables)]` on by default
+
+warning: `clippy_lints` (lib) generated 2 warnings (run `cargo fix --lib -p clippy_lints` to apply 1 suggestion)
+   Compiling clippy v0.1.89 (/Users/barun511/open_source/rust-clippy)
+    Finished `dev` profile [unoptimized + debuginfo] target(s) in 1.81s
+     Running `target/debug/clippy-driver -L ./target/debug -Z no-codegen --edition 2024 /Users/barun511/open_source/clippy-examples/src/main.rs`

tests/ui/ifs_as_logical_ops.fixed

@@ -0,0 +1,10 @@
+#![warn(clippy::ifs_as_logical_ops)]
+
+fn main() {
+    // test code goes here
+}
+
+fn john(b1: bool, b2: bool) -> bool {
+    b2 && false
+    //~^ ifs_as_logical_ops
+}

tests/ui/ifs_as_logical_ops.rs

@@ -0,0 +1,10 @@
+#![warn(clippy::ifs_as_logical_ops)]
+
+fn main() {
+    // test code goes here
+}
+
+fn john(b1: bool, b2: bool) -> bool {
+    if b1 { b2 } else { false }
+    //~^ ifs_as_logical_ops
+}

tests/ui/ifs_as_logical_ops.stderr

@@ -0,0 +1,11 @@
+error: Logical operations are clearer than if conditions in this instance
+  --> tests/ui/ifs_as_logical_ops.rs:8:5
+   |
+LL |     if b1 { b2 } else { false }
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `b2 && false`
+   |
+   = note: `-D clippy::ifs-as-logical-ops` implied by `-D warnings`
+   = help: to override `-D warnings` add `#[allow(clippy::ifs_as_logical_ops)]`
+
+error: aborting due to 1 previous error
+