[move][move-linter] implemen meaningless math operator rules

external-crates/move/crates/move-compiler/src/linters/constant_naming.rs

@@ -19,13 +19,13 @@ use crate::{
     },
 };
 
-use super::{LinterDiagCategory, CONSTANT_NAMING_DIAG_CODE, LINT_WARNING_PREFIX};
+use super::{LinterDiagnosticCategory, CONSTANT_NAMING_DIAG_CODE, LINT_WARNING_PREFIX};
 
 /// Diagnostic information for constant naming violations.
 const CONSTANT_NAMING_DIAG: DiagnosticInfo = custom(
     LINT_WARNING_PREFIX,
     Severity::Warning,
-    LinterDiagCategory::Style as u8,
+    LinterDiagnosticCategory::Style as u8,
     CONSTANT_NAMING_DIAG_CODE,
     "constant should follow naming convention",
 );

external-crates/move/crates/move-compiler/src/linters/meaningless_math_operation.rs

@@ -0,0 +1,102 @@
+//! Detects meaningless math operations like `x * 0`, `x << 0`, `x >> 0`, `x * 1`, `x + 0`, `x - 0`, and `x / 0`.
+//! Aims to reduce code redundancy and improve clarity by flagging operations with no effect.
+use crate::{
+    diag,
+    diagnostics::{
+        codes::{custom, DiagnosticInfo, Severity},
+        WarningFilters,
+    },
+    expansion::ast::Value_,
+    parser::ast::BinOp_,
+    shared::CompilationEnv,
+    typing::{
+        ast::{self as T, Exp, UnannotatedExp_},
+        visitor::{TypingVisitorConstructor, TypingVisitorContext},
+    },
+};
+use move_ir_types::location::Loc;
+
+use super::{LinterDiagnosticCategory, LINT_WARNING_PREFIX, MEANINGLESS_MATH_OP_DIAG_CODE};
+
+const MEANINGLESS_MATH_OP_DIAG: DiagnosticInfo = custom(
+    LINT_WARNING_PREFIX,
+    Severity::Warning,
+    LinterDiagnosticCategory::Complexity as u8,
+    MEANINGLESS_MATH_OP_DIAG_CODE,
+    "Detected a meaningless math operation that has no effect.",
+);
+
+pub struct MeaninglessMathOperation;
+
+pub struct Context<'a> {
+    env: &'a mut CompilationEnv,
+}
+
+impl TypingVisitorConstructor for MeaninglessMathOperation {
+    type Context<'a> = Context<'a>;
+
+    fn context<'a>(env: &'a mut CompilationEnv, _program: &T::Program) -> Self::Context<'a> {
+        Context { env }
+    }
+}
+
+impl TypingVisitorContext for Context<'_> {
+    fn visit_exp_custom(&mut self, exp: &mut T::Exp) -> bool {
+        if let UnannotatedExp_::BinopExp(_, op, _, rhs) = &exp.exp.value {
+            match op.value {
+                BinOp_::Mul | BinOp_::Div => {
+                    if is_zero(&rhs) || (matches!(op.value, BinOp_::Mul) && is_one(&rhs)) {
+                        report_meaningless_math_op(self.env, op.loc);
+                    }
+                }
+                BinOp_::Add | BinOp_::Sub => {
+                    if is_zero(&rhs) {
+                        report_meaningless_math_op(self.env, op.loc);
+                    }
+                }
+                BinOp_::Shl | BinOp_::Shr => {
+                    if is_zero(&rhs) {
+                        report_meaningless_math_op(self.env, op.loc);
+                    }
+                }
+                _ => {}
+            }
+        }
+
+        false
+    }
+    fn add_warning_filter_scope(&mut self, filter: WarningFilters) {
+        self.env.add_warning_filter_scope(filter)
+    }
+
+    fn pop_warning_filter_scope(&mut self) {
+        self.env.pop_warning_filter_scope()
+    }
+}
+
+fn is_zero(exp: &Exp) -> bool {
+    if let UnannotatedExp_::Value(spanned) = &exp.exp.value {
+        matches!(spanned.value, Value_::U64(0))
+    } else {
+        false
+    }
+}
+
+fn is_one(exp: &Exp) -> bool {
+    if let UnannotatedExp_::Value(spanned) = &exp.exp.value {
+        matches!(spanned.value, Value_::U64(1))
+    } else {
+        false
+    }
+}
+
+fn report_meaningless_math_op(env: &mut CompilationEnv, loc: Loc) {
+    let diag = diag!(
+        MEANINGLESS_MATH_OP_DIAG,
+        (
+            loc,
+            "Detected a meaningless math operation that has no effect.",
+        )
+    );
+    env.add_diag(diag);
+}

external-crates/move/crates/move-compiler/src/linters/mod.rs

@@ -1,13 +1,16 @@
 // Copyright (c) The Move Contributors
 // SPDX-License-Identifier: Apache-2.0
 
-use move_symbol_pool::Symbol;
-
 use crate::{
     command_line::compiler::Visitor, diagnostics::codes::WarningFilter,
-    linters::constant_naming::ConstantNamingVisitor, typing::visitor::TypingVisitor,
+    linters::constant_naming::ConstantNamingVisitor,
+    linters::meaningless_math_operation::MeaninglessMathOperation, typing::visitor::TypingVisitor,
 };
+use move_symbol_pool::Symbol;
+
 pub mod constant_naming;
+pub mod meaningless_math_operation;
+
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub enum LintLevel {
     // No linters
@@ -32,22 +35,28 @@ pub enum LinterDiagnosticCategory {
 pub const ALLOW_ATTR_CATEGORY: &str = "lint";
 pub const LINT_WARNING_PREFIX: &str = "Lint ";
 pub const CONSTANT_NAMING_FILTER_NAME: &str = "constant_naming";
-
 pub const CONSTANT_NAMING_DIAG_CODE: u8 = 1;
 
-pub enum LinterDiagCategory {
-    Style,
-}
+pub const MEANINGLESS_MATH_OP_FILTER_NAME: &str = "meaningless_math_op";
+pub const MEANINGLESS_MATH_OP_DIAG_CODE: u8 = 6;
 
 pub fn known_filters() -> (Option<Symbol>, Vec<WarningFilter>) {
     (
         Some(ALLOW_ATTR_CATEGORY.into()),
-        vec![WarningFilter::code(
-            Some(LINT_WARNING_PREFIX),
-            LinterDiagCategory::Style as u8,
-            CONSTANT_NAMING_DIAG_CODE,
-            Some(CONSTANT_NAMING_FILTER_NAME),
-        )],
+        vec![
+            WarningFilter::code(
+                Some(LINT_WARNING_PREFIX),
+                LinterDiagnosticCategory::Style as u8,
+                CONSTANT_NAMING_DIAG_CODE,
+                Some(CONSTANT_NAMING_FILTER_NAME),
+            ),
+            WarningFilter::code(
+                Some(LINT_WARNING_PREFIX),
+                LinterDiagnosticCategory::Complexity as u8,
+                MEANINGLESS_MATH_OP_DIAG_CODE,
+                Some(MEANINGLESS_MATH_OP_FILTER_NAME),
+            ),
+        ],
     )
 }
 
@@ -56,9 +65,12 @@ pub fn linter_visitors(level: LintLevel) -> Vec<Visitor> {
         LintLevel::None => vec![],
         LintLevel::Default => vec![],
         LintLevel::All => {
-            vec![constant_naming::ConstantNamingVisitor::visitor(
-                ConstantNamingVisitor,
-            )]
+            vec![
+                constant_naming::ConstantNamingVisitor::visitor(ConstantNamingVisitor),
+                meaningless_math_operation::MeaninglessMathOperation::visitor(
+                    MeaninglessMathOperation,
+                ),
+            ]
         }
     }
 }

external-crates/move/crates/move-compiler/src/sui_mode/linters/mod.rs

@@ -13,16 +13,15 @@ use crate::{
 };
 use move_ir_types::location::Loc;
 use move_symbol_pool::Symbol;
-
 pub mod coin_field;
 pub mod collection_equality;
 pub mod custom_state_change;
 pub mod freeze_wrapped;
 pub mod public_random;
 pub mod self_transfer;
 pub mod share_owned;
-
 pub const SUI_PKG_NAME: &str = "sui";
+pub const INCLUDE_NEW_RULES: bool = true;
 
 pub const TRANSFER_MOD_NAME: &str = "transfer";
 pub const TRANSFER_FUN: &str = "transfer";
@@ -87,7 +86,7 @@ pub enum LinterDiagnosticCode {
 }
 
 pub fn known_filters() -> (Option<Symbol>, Vec<WarningFilter>) {
-    let filters = vec![
+    let mut filters = vec![
         WarningFilter::All(Some(LINT_WARNING_PREFIX)),
         WarningFilter::code(
             Some(LINT_WARNING_PREFIX),

external-crates/move/crates/move-compiler/tests/linter/correct_meaningless_math_operation.move

@@ -0,0 +1,10 @@
+module 0x42::M {
+    // Intentionally meaningful operations for control cases
+    public fun multiply(x: u64, y: u64): u64 {
+        x * y // This should not trigger the linter
+    }
+
+    public fun divide_by_nonzero(x: u64, y: u64): u64 {
+        x / y // Assuming y is not zero, this should not trigger the linter
+    }
+}

external-crates/move/crates/move-compiler/tests/linter/incorrect_constant_naming.exp

@@ -1,12 +1,12 @@
-warning[Lint W00001]: constant should follow naming convention
+warning[Lint W04001]: constant should follow naming convention
   ┌─ tests/linter/incorrect_constant_naming.move:3:5
   │
 3 │     const Another_BadName: u64 = 42; // Should trigger a warning
   │     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 'Another_BadName' should be ALL_CAPS. Or for error constants, use PascalCase
   │
   = This warning can be suppressed with '#[allow(lint(constant_naming))]' applied to the 'module' or module member ('const', 'fun', or 'struct')
 
-warning[Lint W00001]: constant should follow naming convention
+warning[Lint W04001]: constant should follow naming convention
   ┌─ tests/linter/incorrect_constant_naming.move:4:5
   │
 4 │     const JSON_Max_Size: u64 = 1048576;