[clang-tools-extra] Add clang-tidy check readability-math-missing-parentheses (PR #84481)
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Fri Mar 8 05:38:10 PST 2024
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-clang-tidy
Author: Bhuminjay Soni (11happy)
<details>
<summary>Changes</summary>
**Overview:**
This pull request fixes #<!-- -->80850 where author suggests adding a readability check to detect missing parentheses around mathematical expressions when operators of different priorities are used.
**Testing:**
- Tested the updated code.
- Verified that other functionalities remain unaffected.
**Dependencies:**
- No dependencies on other pull requests.
**CC:**
- @<!-- -->PiotrZSL
---
Full diff: https://github.com/llvm/llvm-project/pull/84481.diff
8 Files Affected:
- (modified) clang-tools-extra/clang-tidy/readability/CMakeLists.txt (+1)
- (added) clang-tools-extra/clang-tidy/readability/MathMissingParenthesesCheck.cpp (+167)
- (added) clang-tools-extra/clang-tidy/readability/MathMissingParenthesesCheck.h (+31)
- (modified) clang-tools-extra/clang-tidy/readability/ReadabilityTidyModule.cpp (+3)
- (modified) clang-tools-extra/docs/ReleaseNotes.rst (+6)
- (modified) clang-tools-extra/docs/clang-tidy/checks/list.rst (+1)
- (added) clang-tools-extra/docs/clang-tidy/checks/readability/math-missing-parentheses.rst (+19)
- (added) clang-tools-extra/test/clang-tidy/checkers/readability/math-missing-parentheses.cpp (+42)
``````````diff
diff --git a/clang-tools-extra/clang-tidy/readability/CMakeLists.txt b/clang-tools-extra/clang-tidy/readability/CMakeLists.txt
index a6c8cbd8eb448a..0d4fa095501dfb 100644
--- a/clang-tools-extra/clang-tidy/readability/CMakeLists.txt
+++ b/clang-tools-extra/clang-tidy/readability/CMakeLists.txt
@@ -27,6 +27,7 @@ add_clang_library(clangTidyReadabilityModule
IsolateDeclarationCheck.cpp
MagicNumbersCheck.cpp
MakeMemberFunctionConstCheck.cpp
+ MathMissingParenthesesCheck.cpp
MisleadingIndentationCheck.cpp
MisplacedArrayIndexCheck.cpp
NamedParameterCheck.cpp
diff --git a/clang-tools-extra/clang-tidy/readability/MathMissingParenthesesCheck.cpp b/clang-tools-extra/clang-tidy/readability/MathMissingParenthesesCheck.cpp
new file mode 100644
index 00000000000000..d9574a9fb7a476
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/readability/MathMissingParenthesesCheck.cpp
@@ -0,0 +1,167 @@
+//===--- MathMissingParenthesesCheck.cpp - clang-tidy ---------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "MathMissingParenthesesCheck.h"
+#include "../utils/ASTUtils.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/Lex/Preprocessor.h"
+#include <set>
+#include <stack>
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::readability {
+
+void MathMissingParenthesesCheck::registerMatchers(MatchFinder *Finder) {
+ Finder->addMatcher(binaryOperator(unless(hasParent(binaryOperator())),
+ hasDescendant(binaryOperator()))
+ .bind("binOp"),
+ this);
+}
+static int precedenceCheck(const char op) {
+ if (op == '/' || op == '*' || op == '%')
+ return 5;
+
+ else if (op == '+' || op == '-')
+ return 4;
+
+ else if (op == '&')
+ return 3;
+ else if (op == '^')
+ return 2;
+
+ else if (op == '|')
+ return 1;
+
+ else
+ return 0;
+}
+static bool isOperand(const char c) {
+ if (c >= 'a' && c <= 'z')
+ return true;
+ else if (c >= 'A' && c <= 'Z')
+ return true;
+ else if (c >= '0' && c <= '9')
+ return true;
+ else if (c == '$')
+ return true;
+ else
+ return false;
+}
+static bool conditionForNegative(const std::string s, int i,
+ const std::string CurStr) {
+ if (CurStr[0] == '-') {
+ if (i == 0) {
+ return true;
+ } else {
+ while (s[i - 1] == ' ') {
+ i--;
+ }
+ if (!isOperand(s[i - 1])) {
+ return true;
+ } else {
+ return false;
+ }
+ }
+ } else {
+ return false;
+ }
+}
+static std::string getOperationOrder(std::string s, std::set<char> &Operators) {
+ std::stack<std::string> StackOne;
+ std::string TempStr = "";
+ for (int i = 0; i < s.length(); i++) {
+ std::string CurStr = "";
+ CurStr += s[i];
+ if (CurStr == " ")
+ continue;
+ else {
+ if (isOperand(CurStr[0]) || conditionForNegative(s, i, CurStr)) {
+ while (i < s.length() && (isOperand(s[i]) || s[i] == '-')) {
+ if (s[i] == '-') {
+ TempStr += "$";
+ } else {
+ TempStr += CurStr;
+ }
+ i++;
+ CurStr = s[i];
+ }
+ TempStr += " ";
+ } else if (CurStr == "(") {
+ StackOne.push("(");
+ } else if (CurStr == ")") {
+ while (StackOne.top() != "(") {
+ TempStr += StackOne.top();
+ StackOne.pop();
+ }
+ StackOne.pop();
+ } else {
+ while (!StackOne.empty() && precedenceCheck(CurStr[0]) <=
+ precedenceCheck((StackOne.top())[0])) {
+ TempStr += StackOne.top();
+ StackOne.pop();
+ }
+ StackOne.push(CurStr);
+ }
+ }
+ }
+ while (!StackOne.empty()) {
+ TempStr += StackOne.top();
+ StackOne.pop();
+ }
+ std::stack<std::string> StackTwo;
+ for (int i = 0; i < TempStr.length(); i++) {
+ if (TempStr[i] == ' ')
+ continue;
+ else if (isOperand(TempStr[i])) {
+ std::string CurStr = "";
+ while (i < TempStr.length() && isOperand(TempStr[i])) {
+ if (TempStr[i] == '$') {
+ CurStr += "-";
+ } else {
+ CurStr += TempStr[i];
+ }
+ i++;
+ }
+ StackTwo.push(CurStr);
+ } else {
+ std::string OperandOne = StackTwo.top();
+ StackTwo.pop();
+ std::string OperandTwo = StackTwo.top();
+ StackTwo.pop();
+ Operators.insert(TempStr[i]);
+ StackTwo.push("(" + OperandTwo + " " + TempStr[i] + " " + OperandOne +
+ ")");
+ }
+ }
+ return StackTwo.top();
+}
+void MathMissingParenthesesCheck::check(
+ const MatchFinder::MatchResult &Result) {
+ const auto *BinOp = Result.Nodes.getNodeAs<BinaryOperator>("binOp");
+ if (!BinOp)
+ return;
+ clang::SourceManager &SM = *Result.SourceManager;
+ clang::LangOptions LO = Result.Context->getLangOpts();
+ clang::CharSourceRange Range =
+ clang::CharSourceRange::getTokenRange(BinOp->getSourceRange());
+ std::string Expression = clang::Lexer::getSourceText(Range, SM, LO).str();
+ std::set<char> Operators;
+ std::string FinalExpression = getOperationOrder(Expression, Operators);
+ if (Operators.size() > 1) {
+ if (FinalExpression.length() > 2) {
+ FinalExpression = FinalExpression.substr(1, FinalExpression.length() - 2);
+ }
+ diag(BinOp->getBeginLoc(),
+ "add parantheses to clarify the precedence of operations")
+ << FixItHint::CreateReplacement(Range, FinalExpression);
+ }
+}
+
+} // namespace clang::tidy::readability
diff --git a/clang-tools-extra/clang-tidy/readability/MathMissingParenthesesCheck.h b/clang-tools-extra/clang-tidy/readability/MathMissingParenthesesCheck.h
new file mode 100644
index 00000000000000..60b402831b45e0
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/readability/MathMissingParenthesesCheck.h
@@ -0,0 +1,31 @@
+//===--- MathMissingParenthesesCheck.h - clang-tidy -------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_MATHMISSINGPARENTHESESCHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_MATHMISSINGPARENTHESESCHECK_H
+
+#include "../ClangTidyCheck.h"
+
+namespace clang::tidy::readability {
+
+/// Checks for mathematical expressions that involve operators of different
+/// priorities.
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/readability/math-missing-parentheses.html
+class MathMissingParenthesesCheck : public ClangTidyCheck {
+public:
+ MathMissingParenthesesCheck(StringRef Name, ClangTidyContext *Context)
+ : ClangTidyCheck(Name, Context) {}
+ void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+ void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+};
+
+} // namespace clang::tidy::readability
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_MATHMISSINGPARENTHESESCHECK_H
diff --git a/clang-tools-extra/clang-tidy/readability/ReadabilityTidyModule.cpp b/clang-tools-extra/clang-tidy/readability/ReadabilityTidyModule.cpp
index 87b299bf1ef1c5..b198153d27ee49 100644
--- a/clang-tools-extra/clang-tidy/readability/ReadabilityTidyModule.cpp
+++ b/clang-tools-extra/clang-tidy/readability/ReadabilityTidyModule.cpp
@@ -31,6 +31,7 @@
#include "IsolateDeclarationCheck.h"
#include "MagicNumbersCheck.h"
#include "MakeMemberFunctionConstCheck.h"
+#include "MathMissingParenthesesCheck.h"
#include "MisleadingIndentationCheck.h"
#include "MisplacedArrayIndexCheck.h"
#include "NamedParameterCheck.h"
@@ -101,6 +102,8 @@ class ReadabilityModule : public ClangTidyModule {
"readability-identifier-naming");
CheckFactories.registerCheck<ImplicitBoolConversionCheck>(
"readability-implicit-bool-conversion");
+ CheckFactories.registerCheck<MathMissingParenthesesCheck>(
+ "readability-math-missing-parentheses");
CheckFactories.registerCheck<RedundantInlineSpecifierCheck>(
"readability-redundant-inline-specifier");
CheckFactories.registerCheck<InconsistentDeclarationParameterNameCheck>(
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index fd2cba4e4f463b..61b9665ffe73ed 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -100,6 +100,12 @@ Improvements to clang-tidy
New checks
^^^^^^^^^^
+- New :doc:`readability-math-missing-parentheses
+ <clang-tidy/checks/readability/math-missing-parentheses>` check.
+
+ Checks for mathematical expressions that involve operators
+ of different priorities.
+
New check aliases
^^^^^^^^^^^^^^^^^
diff --git a/clang-tools-extra/docs/clang-tidy/checks/list.rst b/clang-tools-extra/docs/clang-tidy/checks/list.rst
index f773e80b562e4f..0cc5c217899d4d 100644
--- a/clang-tools-extra/docs/clang-tidy/checks/list.rst
+++ b/clang-tools-extra/docs/clang-tidy/checks/list.rst
@@ -359,6 +359,7 @@ Clang-Tidy Checks
:doc:`readability-isolate-declaration <readability/isolate-declaration>`, "Yes"
:doc:`readability-magic-numbers <readability/magic-numbers>`,
:doc:`readability-make-member-function-const <readability/make-member-function-const>`, "Yes"
+ :doc:`readability-math-missing-parentheses <readability/math-missing-parentheses>`, "Yes"
:doc:`readability-misleading-indentation <readability/misleading-indentation>`,
:doc:`readability-misplaced-array-index <readability/misplaced-array-index>`, "Yes"
:doc:`readability-named-parameter <readability/named-parameter>`, "Yes"
diff --git a/clang-tools-extra/docs/clang-tidy/checks/readability/math-missing-parentheses.rst b/clang-tools-extra/docs/clang-tidy/checks/readability/math-missing-parentheses.rst
new file mode 100644
index 00000000000000..fb3167e8e0f8f1
--- /dev/null
+++ b/clang-tools-extra/docs/clang-tidy/checks/readability/math-missing-parentheses.rst
@@ -0,0 +1,19 @@
+.. title:: clang-tidy - readability-math-missing-parentheses
+
+readability-math-missing-parentheses
+====================================
+
+Checks for mathematical expressions that involve operators of different priorities.
+
+Before:
+
+.. code-block:: c++
+
+ int x = 1 + 2 * 3 - 4 / 5;
+
+
+After:
+
+.. code-block:: c++
+
+ int x = (1 + (2 * 3)) - (4 / 5);
\ No newline at end of file
diff --git a/clang-tools-extra/test/clang-tidy/checkers/readability/math-missing-parentheses.cpp b/clang-tools-extra/test/clang-tidy/checkers/readability/math-missing-parentheses.cpp
new file mode 100644
index 00000000000000..54cc0d4dabbdee
--- /dev/null
+++ b/clang-tools-extra/test/clang-tidy/checkers/readability/math-missing-parentheses.cpp
@@ -0,0 +1,42 @@
+// RUN: %check_clang_tidy %s readability-math-missing-parentheses %t
+
+// FIXME: Add something that triggers the check here.
+void f(){
+ //CHECK-MESSAGES: :[[@LINE+2]]:13: warning: add parantheses to clarify the precedence of operations [readability-math-missing-parentheses]
+ //CHECK-FIXES: int a = 1 + (2 * 3);
+ int a = 1 + 2 * 3;
+
+ int b = 1 + 2 + 3; // No warning
+
+ int c = 1 * 2 * 3; // No warning
+
+ //CHECK-MESSAGES: :[[@LINE+2]]:13: warning: add parantheses to clarify the precedence of operations [readability-math-missing-parentheses]
+ //CHECK-FIXES: int d = (1 + (2 * 3)) - (4 / 5);
+ int d = 1 + 2 * 3 - 4 / 5;
+
+ //CHECK-MESSAGES: :[[@LINE+2]]:13: warning: add parantheses to clarify the precedence of operations [readability-math-missing-parentheses]
+ //CHECK-FIXES: int e = (1 & (2 + 3)) | (4 * 5);
+ int e = 1 & 2 + 3 | 4 * 5;
+
+ //CHECK-MESSAGES: :[[@LINE+2]]:13: warning: add parantheses to clarify the precedence of operations [readability-math-missing-parentheses]
+ //CHECK-FIXES: int f = (1 * -2) + 4;
+ int f = 1 * -2 + 4;
+
+ //CHECK-MESSAGES: :[[@LINE+2]]:13: warning: add parantheses to clarify the precedence of operations [readability-math-missing-parentheses]
+ //CHECK-FIXES: int g = (((1 * 2) * 3) + 4) + 5;
+ int g = 1 * 2 * 3 + 4 + 5;
+
+ // CHECK-MESSAGES: :[[@LINE+2]]:13: warning: add parantheses to clarify the precedence of operations [readability-math-missing-parentheses]
+ // CHECK-FIXES: int h = (120 & (2 + 3)) | (22 * 5);
+ int h = 120 & 2 + 3 | 22 * 5;
+
+ int i = 1 & 2 & 3; // No warning
+
+ int j = 1 | 2 | 3; // No warning
+
+ int k = 1 ^ 2 ^ 3; // No warning
+
+ // CHECK-MESSAGES: :[[@LINE+2]]:13: warning: add parantheses to clarify the precedence of operations [readability-math-missing-parentheses]
+ // CHECK-FIXES: int l = (1 + 2) ^ 3;
+ int l = 1 + 2 ^ 3;
+}
``````````
</details>
https://github.com/llvm/llvm-project/pull/84481
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