[clang-tools-extra] [llvm] [clang] Add clang-tidy check to suggest replacement of conditional statement with std::min/std::max (PR #77816)

[Piotr Zegar via cfe-commits]

================
@@ -0,0 +1,151 @@
+//===--- UseStdMinMaxCheck.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 "UseStdMinMaxCheck.h"
+#include "../utils/ASTUtils.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/Lex/Preprocessor.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::readability {
+
+static const llvm::StringRef AlgorithmHeader("<algorithm>");
+
+static bool MinCondition(const BinaryOperator::Opcode &Op, const Expr *CondLhs,
+                         const Expr *CondRhs, const Expr *AssignLhs,
+                         const Expr *AssignRhs, const ASTContext &Context) {
+  if ((Op == BO_LT || Op == BO_LE) &&
+      (tidy::utils::areStatementsIdentical(CondLhs, AssignRhs, Context) &&
+       tidy::utils::areStatementsIdentical(CondRhs, AssignLhs, Context)))
+    return true;
+
+  if ((Op == BO_GT || Op == BO_GE) &&
+      (tidy::utils::areStatementsIdentical(CondLhs, AssignLhs, Context) &&
+       tidy::utils::areStatementsIdentical(CondRhs, AssignRhs, Context)))
+    return true;
+
+  return false;
+}
+
+static bool MaxCondition(const BinaryOperator::Opcode &Op, const Expr *CondLhs,
+                         const Expr *CondRhs, const Expr *AssignLhs,
+                         const Expr *AssignRhs, const ASTContext &Context) {
+  if ((Op == BO_LT || Op == BO_LE) &&
+      (tidy::utils::areStatementsIdentical(CondLhs, AssignLhs, Context) &&
+       tidy::utils::areStatementsIdentical(CondRhs, AssignRhs, Context)))
+    return true;
+
+  if ((Op == BO_GT || Op == BO_GE) &&
+      (tidy::utils::areStatementsIdentical(CondLhs, AssignRhs, Context) &&
+       tidy::utils::areStatementsIdentical(CondRhs, AssignLhs, Context)))
+    return true;
+
+  return false;
+}
+
+static std::string
+CreateReplacement(const bool UseMax, const BinaryOperator::Opcode &Op,
+                  const Expr *CondLhs, const Expr *CondRhs,
+                  const Expr *AssignLhs, const ASTContext &Context,
+                  const SourceManager &Source, const LangOptions &LO,
+                  const StringRef &FunctionName) {
+  const auto CondLhsStr = Lexer::getSourceText(
+      Source.getExpansionRange(CondLhs->getSourceRange()), Source, LO);
+  const auto CondRhsStr = Lexer::getSourceText(
+      Source.getExpansionRange(CondRhs->getSourceRange()), Source, LO);
+  const auto AssignLhsStr = Lexer::getSourceText(
+      Source.getExpansionRange(AssignLhs->getSourceRange()), Source, LO);
+  return (AssignLhsStr + " = " + FunctionName +
+          ((CondLhs->getType() != CondRhs->getType())
+               ? "<" + AssignLhs->getType().getAsString() + ">("
+               : "(") +
+          CondLhsStr + ", " + CondRhsStr + ");")
+      .str();
+}
+
+UseStdMinMaxCheck::UseStdMinMaxCheck(StringRef Name, ClangTidyContext *Context)
+    : ClangTidyCheck(Name, Context),
+      IncludeInserter(Options.getLocalOrGlobal("IncludeStyle",
+                                               utils::IncludeSorter::IS_LLVM),
+                      areDiagsSelfContained()) {}
+
+void UseStdMinMaxCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
+  Options.store(Opts, "IncludeStyle", IncludeInserter.getStyle());
+}
+
+void UseStdMinMaxCheck::registerMatchers(MatchFinder *Finder) {
+  auto AssignOperator =
+      binaryOperator(hasOperatorName("="), hasLHS(expr().bind("AssignLhs")),
+                     hasRHS(expr().bind("AssignRhs")));
+
+  Finder->addMatcher(
+      ifStmt(
+          stmt().bind("if"),
+          unless(hasElse(stmt())), // Ensure `if` has no `else`
+          hasCondition(binaryOperator(hasAnyOperatorName("<", ">", "<=", ">="),
+                                      hasLHS(expr().bind("CondLhs")),
+                                      hasRHS(expr().bind("CondRhs")))
+                           .bind("binaryOp")),
+          hasThen(
+              anyOf(stmt(AssignOperator),
+                    compoundStmt(statementCountIs(1), has(AssignOperator)))),
+          hasParent(stmt(unless(ifStmt(hasElse(
+              equalsBoundNode("if"))))))), // Ensure `if` has no `else if`
+      this);
+}
+
+void UseStdMinMaxCheck::registerPPCallbacks(const SourceManager &SM,
+                                            Preprocessor *PP,
+                                            Preprocessor *ModuleExpanderPP) {
+  IncludeInserter.registerPreprocessor(PP);
+}
+
+void UseStdMinMaxCheck::check(const MatchFinder::MatchResult &Result) {
+  const auto *If = Result.Nodes.getNodeAs<IfStmt>("if");
+  const auto &Context = *Result.Context;
+  const auto &LO = Context.getLangOpts();
+  const auto *CondLhs = Result.Nodes.getNodeAs<Expr>("CondLhs");
+  const auto *CondRhs = Result.Nodes.getNodeAs<Expr>("CondRhs");
+  const auto *AssignLhs = Result.Nodes.getNodeAs<Expr>("AssignLhs");
+  const auto *AssignRhs = Result.Nodes.getNodeAs<Expr>("AssignRhs");
+  const auto *BinaryOp = Result.Nodes.getNodeAs<BinaryOperator>("binaryOp");
+  const auto BinaryOpcode = BinaryOp->getOpcode();
+  const auto OperatorStr = BinaryOp->getOpcodeStr();
+  const SourceManager &Source = Context.getSourceManager();
+  const SourceLocation IfLocation = If->getIfLoc();
+  const SourceLocation ThenLocation = If->getEndLoc();
+
+  // Ignore Macros
+  if (IfLocation.isMacroID() || ThenLocation.isMacroID())
+    return;
+
+  auto ReplaceAndDiagnose = [&](bool UseMax) {
----------------
PiotrZSL wrote:

change UseMax into const llvm::StringRef FunctionName, and pass strings directly in line 144 and 147, no need for bool

https://github.com/llvm/llvm-project/pull/77816