[clang-tools-extra] Add clang-tidy check readability-math-missing-parentheses (PR #84481)

[Bhuminjay Soni via cfe-commits]

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@@ -0,0 +1,87 @@
+//===--- 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"
+
+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 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 bool addParantheses(const BinaryOperator *BinOp,
+                           const BinaryOperator *ParentBinOp,
+                           std::vector<clang::SourceRange> &Insertions) {
+  bool NeedToDiagnose = false;
+  if (!BinOp)
+    return NeedToDiagnose;
+
+  if (ParentBinOp != nullptr &&
+      getPrecedence(BinOp) != getPrecedence(ParentBinOp)) {
+    NeedToDiagnose = true;
+    const clang::SourceLocation StartLoc = BinOp->getBeginLoc();
+    const clang::SourceLocation EndLoc = BinOp->getEndLoc().getLocWithOffset(1);
+    Insertions.push_back(clang::SourceRange(StartLoc, EndLoc));
+  }
+
+  NeedToDiagnose |= addParantheses(
+      dyn_cast<BinaryOperator>(BinOp->getLHS()->IgnoreImpCasts()), BinOp,
+      Insertions);
+  NeedToDiagnose |= addParantheses(
+      dyn_cast<BinaryOperator>(BinOp->getRHS()->IgnoreImpCasts()), BinOp,
+      Insertions);
+  return NeedToDiagnose;
+}
+
+void MathMissingParenthesesCheck::check(
+    const MatchFinder::MatchResult &Result) {
+  const auto *BinOp = Result.Nodes.getNodeAs<BinaryOperator>("binOp");
+  bool NeedToDiagnose = false;
+  std::vector<clang::SourceRange> Insertions;
+  const clang::SourceLocation StartLoc = BinOp->getBeginLoc();
+
+  if (addParantheses(BinOp, nullptr, Insertions)) {
+    auto const &Diag = diag(
+        StartLoc, "add parantheses to clarify the precedence of operations");
+    for (const auto &Insertion : Insertions) {
+      Diag << FixItHint::CreateInsertion(Insertion.getBegin(), "(");
+      Diag << FixItHint::CreateInsertion(Insertion.getEnd(), ")");
+      Diag << SourceRange(Insertion.getBegin(), Insertion.getEnd());
----------------
11happy wrote:

done

https://github.com/llvm/llvm-project/pull/84481