Directional commit for ifs-as-logical-ops

Author: barun511

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

@@ -197,6 +197,7 @@ 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 +1,57 @@
+use clippy_utils::diagnostics::span_lint_and_sugg;
+use clippy_utils::source::snippet;
+use rustc_ast::ast::*;
+use rustc_ast::token::LitKind;
+use rustc_errors::Applicability;
+use rustc_lint::{EarlyContext, EarlyLintPass};
+use rustc_session::declare_lint_pass;
+use rustc_span::kw;
+
+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 EarlyLintPass for IfsAsLogicalOps {
+    fn check_expr(&mut self, cx: &EarlyContext<'_>, e: &Expr) {
+        if let ExprKind::If(cond, cond_inner, Some(els)) = &e.kind
+            && let Some(inner_if_stmt) = cond_inner.stmts.first()
+            && let ExprKind::Block(inner_block, _label) = &els.kind
+            && let Some(stmt) = inner_block.stmts.first()
+            && let StmtKind::Expr(els_expr) = &stmt.kind
+            && let ExprKind::Lit(lit) = &els_expr.kind
+            && let LitKind::Bool = &lit.kind
+            && lit.symbol == kw::False
+        {
+            let if_cond_snippet = snippet(cx, cond.span, "..");
+            let conjunction_snippet = " && ";
+            let inner_snippet = snippet(cx, inner_if_stmt.span, "..");
+            let final_snippet = if_cond_snippet + conjunction_snippet + inner_snippet;
+
+            span_lint_and_sugg(
+                cx,
+                IFS_AS_LOGICAL_OPS,
+                e.span,
+                "Logical operations are clearer than if conditions in this instance",
+                "try",
+                final_snippet.to_string(),
+                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;
@@ -946,5 +947,6 @@ pub fn register_lints(store: &mut rustc_lint::LintStore, conf: &'static Conf) {
     store.register_late_pass(|_| Box::new(single_option_map::SingleOptionMap));
     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_early_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 +1,102 @@
+    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.01s
+     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)
+error[E0423]: expected function, tuple struct or tuple variant, found enum `Option`
+   --> clippy_lints/src/ifs_as_logical_ops.rs:41:17
+    |
+41  |                 Option(cond.span),
+    |                 ^^^^^^
+    |
+    = help: you might have meant to construct the enum's non-tuple variant
+note: these items exist but are inaccessible
+   --> clippy_lints/src/len_zero.rs:321:5
+    |
+321 |     Option(DefId),
+    |     ^^^^^^^^^^^^^ `crate::len_zero::LenOutput::Option`: not accessible
+    |
+   ::: clippy_lints/src/question_mark.rs:320:5
+    |
+320 |     Option,
+    |     ^^^^^^ `crate::question_mark::TryMode::Option`: not accessible
+    |
+   ::: clippy_lints/src/unwrap.rs:84:5
+    |
+84  |     Option,
+    |     ^^^^^^ `crate::unwrap::UnwrappableKind::Option`: not accessible
+help: try to construct one of the enum's variants
+    |
+41  -                 Option(cond.span),
+41  +                 std::option::Option::Some(cond.span),
+    |
+help: consider importing one of these items instead
+    |
+1   + use clippy_utils::sym::Option;
+    |
+1   + use rustc_hir::LangItem::Option;
+    |
+1   + use rustc_middle::ty::lang_items::TraitSolverLangItem::Option;
+    |
+1   + use rustc_span::sym::Option;
+    |
+      and 1 other candidate
+
+warning: unnecessary qualification
+  --> clippy_lints/src/ifs_as_logical_ops.rs:27:57
+   |
+27 |     fn check_expr(&mut self, cx: &EarlyContext<'_>, e: &rustc_ast::Expr) {
+   |                                                         ^^^^^^^^^^^^^^^
+   |
+note: the lint level is defined here
+  --> clippy_lints/src/lib.rs:27:5
+   |
+27 |     unused_qualifications,
+   |     ^^^^^^^^^^^^^^^^^^^^^
+help: remove the unnecessary path segments
+   |
+27 -     fn check_expr(&mut self, cx: &EarlyContext<'_>, e: &rustc_ast::Expr) {
+27 +     fn check_expr(&mut self, cx: &EarlyContext<'_>, e: &Expr) {
+   |
+
+error[E0308]: mismatched types
+  --> clippy_lints/src/ifs_as_logical_ops.rs:31:20
+   |
+31 |             && let StmtKind::Expr(els_expr) = stmt
+   |                    ^^^^^^^^^^^^^^^^^^^^^^^^   ---- this expression has type `&rustc_ast::Stmt`
+   |                    |
+   |                    expected `Stmt`, found `StmtKind`
+
+error[E0308]: mismatched types
+  --> clippy_lints/src/ifs_as_logical_ops.rs:32:20
+   |
+32 |             && let ExprKind::Lit(lit) = els_expr
+   |                    ^^^^^^^^^^^^^^^^^^   -------- this expression has type `&P<rustc_ast::Expr>`
+   |                    |
+   |                    expected `P<Expr>`, found `ExprKind`
+   |
+   = note: expected struct `P<rustc_ast::Expr>`
+                found enum `rustc_ast::ExprKind`
+
+error[E0308]: mismatched types
+  --> clippy_lints/src/ifs_as_logical_ops.rs:33:20
+   |
+33 |             && let LitKind::Bool(value) = lit
+   |                    ^^^^^^^^^^^^^^^^^^^^   --- this expression has type `&rustc_ast::token::Lit`
+   |                    |
+   |                    expected `Lit`, found `LitKind`
+
+error[E0277]: can't compare `&bool` with `bool`
+  --> clippy_lints/src/ifs_as_logical_ops.rs:34:22
+   |
+34 |             && value == false
+   |                      ^^ no implementation for `&bool == bool`
+   |
+   = help: the trait `std::cmp::PartialEq<bool>` is not implemented for `&bool`
+help: consider dereferencing here
+   |
+34 |             && *value == false
+   |                +
+
+Some errors have detailed explanations: E0277, E0308, E0423.
+For more information about an error, try `rustc --explain E0277`.
+warning: `clippy_lints` (lib) generated 1 warning
+error: could not compile `clippy_lints` (lib) due to 5 previous errors; 1 warning emitted

tests/ui/ifs_as_logical_ops.rs

@@ -0,0 +1,11 @@
+#![allow(unused)]
+#![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
+}