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

[Piotr Zegar via cfe-commits]

================
@@ -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) {
----------------
PiotrZSL wrote:

won't work when dealing with function calls like:

`x.get(10+5) * x.get(10-5) - x.get(10+5) / x.get("string (something")`
avoid manual parsing, Clang AST already does all work., and you do not need to compare all at once, you can do that one by one

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