Add assert(true) and assert(false) lints

Author: A.A.Abroskin

clippy_lints/src/assert_checks.rs

@@ -0,0 +1,78 @@
+// Copyright 2014-2018 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use crate::rustc::hir::{Expr, ExprKind};
+use crate::rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
+use crate::rustc::{declare_tool_lint, lint_array};
+use crate::syntax::ast::LitKind;
+use crate::utils::{is_direct_expn_of, span_lint};
+use if_chain::if_chain;
+
+/// **What it does:** Check explicit call assert!(true)
+///
+/// **Why is this bad?** Will be optimized out by the compiler
+///
+/// **Known problems:** None
+///
+/// **Example:**
+/// ```rust
+/// assert!(true)
+/// ```
+declare_clippy_lint! {
+    pub EXPLICIT_TRUE,
+    correctness,
+    "assert!(true) will be optimized out by the compiler"
+}
+
+/// **What it does:** Check explicit call assert!(false)
+///
+/// **Why is this bad?** Should probably be replaced by a panic!()
+///
+/// **Known problems:** None
+///
+/// **Example:**
+/// ```rust
+/// assert!(false)
+/// ```
+declare_clippy_lint! {
+    pub EXPLICIT_FALSE,
+    correctness,
+    "assert!(false) should probably be replaced by a panic!()r"
+}
+
+pub struct AssertChecks;
+
+impl LintPass for AssertChecks {
+    fn get_lints(&self) -> LintArray {
+        lint_array![EXPLICIT_TRUE, EXPLICIT_FALSE]
+    }
+}
+
+impl<'a, 'tcx> LateLintPass<'a, 'tcx> for AssertChecks {
+    fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, e: &'tcx Expr) {
+        if_chain! {
+            if is_direct_expn_of(e.span, "assert").is_some();
+            if let ExprKind::Unary(_, ref lit) = e.node;
+            if let ExprKind::Lit(ref inner) = lit.node;
+            then {
+                match inner.node {
+                    LitKind::Bool(true) => {
+                        span_lint(cx, EXPLICIT_TRUE, e.span,
+                            "assert!(true) will be optimized out by the compiler");
+                    },
+                    LitKind::Bool(false) => {
+                        span_lint(cx, EXPLICIT_FALSE, e.span,
+                            "assert!(false) should probably be replaced by a panic!()");
+                    },
+                    _ => (),
+                }
+            }
+        }
+    }
+}

clippy_lints/src/lib.rs

@@ -87,6 +87,7 @@ mod utils;
 // begin lints modules, do not remove this comment, it’s used in `update_lints`
 pub mod approx_const;
 pub mod arithmetic;
+pub mod assert_checks;
 pub mod assign_ops;
 pub mod attrs;
 pub mod bit_mask;
@@ -483,6 +484,7 @@ pub fn register_plugins(reg: &mut rustc_plugin::Registry<'_>, conf: &Conf) {
     reg.register_late_lint_pass(box ptr_offset_with_cast::Pass);
     reg.register_late_lint_pass(box redundant_clone::RedundantClone);
     reg.register_late_lint_pass(box slow_vector_initialization::Pass);
+    reg.register_late_lint_pass(box assert_checks::AssertChecks);
 
     reg.register_lint_group("clippy::restriction", Some("clippy_restriction"), vec![
         arithmetic::FLOAT_ARITHMETIC,
@@ -560,6 +562,8 @@ pub fn register_plugins(reg: &mut rustc_plugin::Registry<'_>, conf: &Conf) {
 
     reg.register_lint_group("clippy::all", Some("clippy"), vec![
         approx_const::APPROX_CONSTANT,
+        assert_checks::EXPLICIT_TRUE,
+        assert_checks::EXPLICIT_FALSE,
         assign_ops::ASSIGN_OP_PATTERN,
         assign_ops::MISREFACTORED_ASSIGN_OP,
         attrs::DEPRECATED_CFG_ATTR,
@@ -939,6 +943,8 @@ pub fn register_plugins(reg: &mut rustc_plugin::Registry<'_>, conf: &Conf) {
 
     reg.register_lint_group("clippy::correctness", Some("clippy_correctness"), vec![
         approx_const::APPROX_CONSTANT,
+        assert_checks::EXPLICIT_TRUE,
+        assert_checks::EXPLICIT_FALSE,
         attrs::DEPRECATED_SEMVER,
         attrs::USELESS_ATTRIBUTE,
         bit_mask::BAD_BIT_MASK,

tests/ui/assert_checks.rs

@@ -0,0 +1,13 @@
+// Copyright 2014-2018 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+fn main() {
+    assert!(true);
+    assert!(false);
+}

tests/ui/assert_checks.stderr

@@ -0,0 +1,18 @@
+error: assert!(true) will be optimized out by the compiler
+  --> $DIR/assert_checks.rs:11:5
+   |
+11 |     assert!(true);
+   |     ^^^^^^^^^^^^^^
+   |
+   = note: #[deny(clippy::explicit_true)] on by default
+
+error: assert!(false) should probably be replaced by a panic!()
+  --> $DIR/assert_checks.rs:12:5
+   |
+12 |     assert!(false);
+   |     ^^^^^^^^^^^^^^^
+   |
+   = note: #[deny(clippy::explicit_false)] on by default
+
+error: aborting due to 2 previous errors
+

tests/ui/attrs.rs

@@ -8,7 +8,7 @@
 // except according to those terms.
 
 #![warn(clippy::inline_always, clippy::deprecated_semver)]
-
+#![allow(clippy::assert_checks::explicit_true)]
 #[inline(always)]
 fn test_attr_lint() {
     assert!(true)

tests/ui/empty_line_after_outer_attribute.rs

@@ -8,7 +8,7 @@
 // except according to those terms.
 
 #![warn(clippy::empty_line_after_outer_attr)]
-
+#![allow(clippy::assert_checks::explicit_true)]
 // This should produce a warning
 #[crate_type = "lib"]
 

tests/ui/panic_unimplemented.rs

@@ -8,7 +8,7 @@
 // except according to those terms.
 
 #![warn(clippy::panic_params, clippy::unimplemented)]
-
+#![allow(clippy::assert_checks::explicit_true)]
 fn missing() {
     if true {
         panic!("{}");