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

[Julian Schmidt via cfe-commits]

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@@ -0,0 +1,68 @@
+//===--- 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);
+}
+
+void addParantheses(
+    const BinaryOperator *BinOp, const BinaryOperator *ParentBinOp,
+    bool &NeedToDiagnose,
+    std::vector<std::pair<clang::SourceLocation, clang::SourceLocation>>
+        &Insertions) {
+  if (!BinOp)
+    return;
+
+  if (ParentBinOp != nullptr &&
+      ParentBinOp->getOpcode() != BinOp->getOpcode()) {
+    NeedToDiagnose = true;
+  }
+  const clang::SourceLocation StartLoc = BinOp->getBeginLoc();
+  const clang::SourceLocation EndLoc = BinOp->getEndLoc().getLocWithOffset(1);
+  Insertions.push_back({StartLoc, EndLoc});
+  addParantheses(dyn_cast<BinaryOperator>(BinOp->getLHS()->IgnoreImpCasts()),
+                 BinOp, NeedToDiagnose, Insertions);
+  addParantheses(dyn_cast<BinaryOperator>(BinOp->getRHS()->IgnoreImpCasts()),
+                 BinOp, NeedToDiagnose, Insertions);
+}
+
+void MathMissingParenthesesCheck::check(
+    const MatchFinder::MatchResult &Result) {
+  const auto *BinOp = Result.Nodes.getNodeAs<BinaryOperator>("binOp");
+  bool NeedToDiagnose = false;
+  std::vector<std::pair<clang::SourceLocation, clang::SourceLocation>>
+      Insertions;
+  addParantheses(BinOp, nullptr, NeedToDiagnose, Insertions);
+  const clang::SourceLocation StartLoc = BinOp->getBeginLoc();
+  const clang::SourceLocation EndLoc = BinOp->getEndLoc().getLocWithOffset(1);
+  const clang::SourceRange range(StartLoc, EndLoc);
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5chmidti wrote:

`range` and `EndLoc` are unused

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