Add clang-tidy check readability-math-missing-parentheses

clang-tools-extra/clang-tidy/readability/CMakeLists.txt

@@ -28,6 +28,7 @@ add_clang_library(clangTidyReadabilityModule
   IsolateDeclarationCheck.cpp
   MagicNumbersCheck.cpp
   MakeMemberFunctionConstCheck.cpp
+  MathMissingParenthesesCheck.cpp
   MisleadingIndentationCheck.cpp
   MisplacedArrayIndexCheck.cpp
   NamedParameterCheck.cpp

clang-tools-extra/clang-tidy/readability/MathMissingParenthesesCheck.cpp

@@ -0,0 +1,97 @@
+//===--- 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 "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/Lex/Lexer.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::readability {
+
+void MathMissingParenthesesCheck::registerMatchers(MatchFinder *Finder) {
+  Finder->addMatcher(binaryOperator(unless(hasParent(binaryOperator())),
+                                    unless(isAssignmentOperator()),
+                                    unless(isComparisonOperator()),
+                                    unless(hasAnyOperatorName("&&", "||")),
+                                    hasDescendant(binaryOperator()))
+                         .bind("binOp"),
+                     this);
+}
+
+static int getPrecedence(const BinaryOperator *BinOp) {
+  if (!BinOp)
+    return 0;
+  switch (BinOp->getOpcode()) {
+  case BO_Mul:
+  case BO_Div:
+  case BO_Rem:
+    return 5;
+  case BO_Add:
+  case BO_Sub:
+    return 4;
+  case BO_And:
+    return 3;
+  case BO_Xor:
+    return 2;
+  case BO_Or:
+    return 1;
+  default:
+    return 0;
+  }
+}
+static void addParantheses(const BinaryOperator *BinOp,
+                           const BinaryOperator *ParentBinOp,
+                           ClangTidyCheck *Check,
+                           const clang::SourceManager &SM,
+                           const clang::LangOptions &LangOpts) {
+  if (!BinOp)
+    return;
+
+  int Precedence1 = getPrecedence(BinOp);
+  int Precedence2 = getPrecedence(ParentBinOp);
+
+  if (ParentBinOp != nullptr && Precedence1 != Precedence2) {
+    const clang::SourceLocation StartLoc = BinOp->getBeginLoc();
+    const clang::SourceLocation EndLoc =
+        clang::Lexer::getLocForEndOfToken(BinOp->getEndLoc(), 0, SM, LangOpts);
+    if (EndLoc.isInvalid())
+      return;
+
+    Check->diag(StartLoc,
+                "'%0' has higher precedence than '%1'; add parentheses to "
+                "explicitly specify the order of operations")
+        << (Precedence1 > Precedence2 ? BinOp->getOpcodeStr()
+                                      : ParentBinOp->getOpcodeStr())
+        << (Precedence1 > Precedence2 ? ParentBinOp->getOpcodeStr()
+                                      : BinOp->getOpcodeStr())
+        << FixItHint::CreateInsertion(StartLoc, "(")
+        << FixItHint::CreateInsertion(EndLoc, ")")
+        << SourceRange(StartLoc, EndLoc);
+  }
+
+  addParantheses(dyn_cast<BinaryOperator>(BinOp->getLHS()->IgnoreImpCasts()),
+                 BinOp, Check, SM, LangOpts);
+  addParantheses(dyn_cast<BinaryOperator>(BinOp->getRHS()->IgnoreImpCasts()),
+                 BinOp, Check, SM, LangOpts);
+}
+
+void MathMissingParenthesesCheck::check(
+    const MatchFinder::MatchResult &Result) {
+  const auto *BinOp = Result.Nodes.getNodeAs<BinaryOperator>("binOp");
+  std::vector<
+      std::pair<clang::SourceRange, std::pair<const clang::BinaryOperator *,
+                                              const clang::BinaryOperator *>>>
+      Insertions;
+  const SourceManager &SM = *Result.SourceManager;
+  const clang::LangOptions &LO = Result.Context->getLangOpts();
+  addParantheses(BinOp, nullptr, this, SM, LO);
+}
+
+} // namespace clang::tidy::readability

clang-tools-extra/clang-tidy/readability/MathMissingParenthesesCheck.h

@@ -0,0 +1,34 @@
+//===--- 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 {
+
+/// Check for mising parantheses in 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;
+  std::optional<TraversalKind> getCheckTraversalKind() const override {
+    return TK_IgnoreUnlessSpelledInSource;
+  }
+};
+
+} // namespace clang::tidy::readability
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_MATHMISSINGPARENTHESESCHECK_H

clang-tools-extra/clang-tidy/readability/ReadabilityTidyModule.cpp

@@ -32,6 +32,7 @@
 #include "IsolateDeclarationCheck.h"
 #include "MagicNumbersCheck.h"
 #include "MakeMemberFunctionConstCheck.h"
+#include "MathMissingParenthesesCheck.h"
 #include "MisleadingIndentationCheck.h"
 #include "MisplacedArrayIndexCheck.h"
 #include "NamedParameterCheck.h"
@@ -105,6 +106,8 @@ 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>(

clang-tools-extra/docs/ReleaseNotes.rst

@@ -129,6 +129,12 @@ New checks
   Enforces consistent style for enumerators' initialization, covering three
   styles: none, first only, or all initialized explicitly.
 
+- New :doc:`readability-math-missing-parentheses
+  <clang-tidy/checks/readability/math-missing-parentheses>` check.
+
+  Check for missing parentheses in mathematical expressions that involve
+  operators of different priorities.
+
 - New :doc:`readability-use-std-min-max
   <clang-tidy/checks/readability/use-std-min-max>` check.
 

clang-tools-extra/docs/clang-tidy/checks/list.rst

@@ -362,6 +362,7 @@ 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"

clang-tools-extra/docs/clang-tidy/checks/readability/math-missing-parentheses.rst

@@ -0,0 +1,27 @@
+.. title:: clang-tidy - readability-math-missing-parentheses
+
+readability-math-missing-parentheses
+====================================
+
+Check for missing parentheses in mathematical expressions that involve operators
+of different priorities.
+
+Parentheses in mathematical expressions clarify the order
+of operations, especially with different-priority operators. Lengthy or multiline
+expressions can obscure this order, leading to coding errors. IDEs can aid clarity
+by highlighting parentheses. Explicitly using parentheses also clarifies what the 
+developer had in mind when writing the expression. Ensuring their presence reduces
+ambiguity and errors, promoting clearer and more maintainable code.
+
+Before:
+
+.. code-block:: c++
+
+  int x = 1 + 2 * 3 - 4 / 5;
+
+
+After:
+
+.. code-block:: c++
+
+  int x = 1 + (2 * 3) - (4 / 5);

clang-tools-extra/test/clang-tidy/checkers/readability/math-missing-parentheses.cpp

@@ -0,0 +1,120 @@
+// RUN: %check_clang_tidy %s readability-math-missing-parentheses %t
+
+#define MACRO_AND &
+#define MACRO_ADD +
+#define MACRO_OR |
+#define MACRO_MULTIPLY *
+#define MACRO_XOR ^
+#define MACRO_SUBTRACT -
+#define MACRO_DIVIDE /
+
+int foo(){
+    return 5;
+}
+
+int bar(){
+    return 4;
+}
+
+class fun{
+public:
+    int A;
+    double B;
+    fun(){
+        A = 5;
+        B = 5.4;
+    }
+};
+
+void f(){
+    //CHECK-MESSAGES: :[[@LINE+2]]:17: warning: '*' has higher precedence than '+'; add parentheses to explicitly specify the order of operations [readability-math-missing-parentheses]
+    //CHECK-FIXES: int a = 1 + (2 * 3);
+    int a = 1 + 2 * 3;
+
+    int a_negative = 1 + (2 * 3); // No warning
+
+    int b = 1 + 2 + 3; // No warning
+
+    int c = 1 * 2 * 3; // No warning
+
+    //CHECK-MESSAGES: :[[@LINE+3]]:17: warning: '*' has higher precedence than '+'; add parentheses to explicitly specify the order of operations [readability-math-missing-parentheses]
+    //CHECK-MESSAGES: :[[@LINE+2]]:25: warning: '/' has higher precedence than '-'; add parentheses to explicitly specify the order of operations [readability-math-missing-parentheses]
+    //CHECK-FIXES: int d = 1 + (2 * 3) - (4 / 5);
+    int d = 1 + 2 * 3 - 4 / 5;
+
+    int d_negative = 1 + (2 * 3) - (4 / 5); // No warning
+
+    //CHECK-MESSAGES: :[[@LINE+4]]:13: warning: '&' has higher precedence than '|'; add parentheses to explicitly specify the order of operations [readability-math-missing-parentheses]
+    //CHECK-MESSAGES: :[[@LINE+3]]:17: warning: '+' has higher precedence than '&'; add parentheses to explicitly specify the order of operations [readability-math-missing-parentheses]
+    //CHECK-MESSAGES: :[[@LINE+2]]:25: warning: '*' has higher precedence than '|'; add parentheses to explicitly specify the order of operations [readability-math-missing-parentheses]
+    //CHECK-FIXES: int e = (1 & (2 + 3)) | (4 * 5);
+    int e = 1 & 2 + 3 | 4 * 5;
+
+    int e_negative = (1 & (2 + 3)) | (4 * 5); // No warning
+
+    //CHECK-MESSAGES: :[[@LINE+2]]:13: warning: '*' has higher precedence than '+'; add parentheses to explicitly specify the order of operations [readability-math-missing-parentheses]
+    //CHECK-FIXES: int f = (1 * -2) + 4;
+    int f = 1 * -2 + 4;
+
+    int f_negative = (1 * -2) + 4; // No warning
+
+    //CHECK-MESSAGES: :[[@LINE+2]]:13: warning: '*' has higher precedence than '+'; add parentheses to explicitly specify the order of operations [readability-math-missing-parentheses]
+    //CHECK-FIXES: int g = (1 * 2 * 3) + 4 + 5;
+    int g = 1 * 2 * 3 + 4 + 5;
+
+    int g_negative = (1 * 2 * 3) + 4 + 5; // No warning
+
+    //CHECK-MESSAGES: :[[@LINE+4]]:13: warning: '&' has higher precedence than '|'; add parentheses to explicitly specify the order of operations [readability-math-missing-parentheses]
+    //CHECK-MESSAGES: :[[@LINE+3]]:19: warning: '+' has higher precedence than '&'; add parentheses to explicitly specify the order of operations [readability-math-missing-parentheses]
+    //CHECK-MESSAGES: :[[@LINE+2]]:27: warning: '*' has higher precedence than '|'; add parentheses to explicitly specify the order of operations [readability-math-missing-parentheses]
+    //CHECK-FIXES: int h = (120 & (2 + 3)) | (22 * 5);
+    int h = 120 & 2 + 3 | 22 * 5;
+
+    int h_negative = (120 & (2 + 3)) | (22 * 5); // No warning
+
+    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: '+' has higher precedence than '^'; add parentheses to explicitly specify the order of operations [readability-math-missing-parentheses]
+    //CHECK-FIXES: int l = (1 + 2) ^ 3;
+    int l = 1 + 2 ^ 3;
+
+    int l_negative = (1 + 2) ^ 3; // No warning
+
+    //CHECK-MESSAGES: :[[@LINE+2]]:13: warning: '*' has higher precedence than '+'; add parentheses to explicitly specify the order of operations [readability-math-missing-parentheses]
+    //CHECK-FIXES: int m = (2 * foo()) + bar();
+    int m = 2 * foo() + bar();
+
+    int m_negative = (2 * foo()) + bar(); // No warning
+
+    //CHECK-MESSAGES: :[[@LINE+2]]:13: warning: '*' has higher precedence than '+'; add parentheses to explicitly specify the order of operations [readability-math-missing-parentheses]
+    //CHECK-FIXES: int n = (1.05 * foo()) + double(bar());
+    int n = 1.05 * foo() + double(bar());
+
+    int n_negative = (1.05 * foo()) + double(bar()); // No warning
+
+    //CHECK-MESSAGES: :[[@LINE+3]]:17: warning: '*' has higher precedence than '+'; add parentheses to explicitly specify the order of operations [readability-math-missing-parentheses]
+    //CHECK-FIXES: int o = 1 + (obj.A * 3) + obj.B;
+    fun obj;
+    int o = 1 + obj.A * 3 + obj.B;
+
+    int o_negative = 1 + (obj.A * 3) + obj.B; // No warning
+
+    //CHECK-MESSAGES: :[[@LINE+2]]:18: warning: '*' has higher precedence than '+'; add parentheses to explicitly specify the order of operations [readability-math-missing-parentheses]
+    //CHECK-FIXES: int p = 1U + (2 * 3);
+    int p = 1U + 2 * 3;
+
+    int p_negative = 1U + (2 * 3); // No warning
+
+    //CHECK-MESSAGES: :[[@LINE+7]]:13: warning: '+' has higher precedence than '|'; add parentheses to explicitly specify the order of operations [readability-math-missing-parentheses]
+    //CHECK-MESSAGES: :[[@LINE+6]]:25: warning: '*' has higher precedence than '+'; add parentheses to explicitly specify the order of operations [readability-math-missing-parentheses]
+    //CHECK-MESSAGES: :[[@LINE+5]]:53: warning: '&' has higher precedence than '^'; add parentheses to explicitly specify the order of operations [readability-math-missing-parentheses]
+    //CHECK-MESSAGES: :[[@LINE+4]]:53: warning: '^' has higher precedence than '|'; add parentheses to explicitly specify the order of operations [readability-math-missing-parentheses]
+    //CHECK-MESSAGES: :[[@LINE+3]]:77: warning: '-' has higher precedence than '^'; add parentheses to explicitly specify the order of operations [readability-math-missing-parentheses]
+    //CHECK-MESSAGES: :[[@LINE+2]]:94: warning: '/' has higher precedence than '-'; add parentheses to explicitly specify the order of operations [readability-math-missing-parentheses]
+    //CHECK-FIXES: int q = (1 MACRO_ADD (2 MACRO_MULTIPLY 3)) MACRO_OR ((4 MACRO_AND 5) MACRO_XOR (6 MACRO_SUBTRACT (7 MACRO_DIVIDE 8)));
+    int q = 1 MACRO_ADD 2 MACRO_MULTIPLY 3 MACRO_OR 4 MACRO_AND 5 MACRO_XOR 6 MACRO_SUBTRACT 7 MACRO_DIVIDE 8; // No warning
+}