[clang-tools-extra] [clang-tidy] add check to suggest replacement of nested std::min or std::max with initializer lists (PR #85572)

[Piotr Zegar via cfe-commits]

================
@@ -0,0 +1,337 @@
+//===--- MinMaxUseInitializerListCheck.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 "MinMaxUseInitializerListCheck.h"
+#include "../utils/ASTUtils.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/Frontend/CompilerInstance.h"
+#include "clang/Lex/Lexer.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::modernize {
+
+struct FindArgsResult {
+  const Expr *First;
+  const Expr *Last;
+  const Expr *Compare;
+  std::vector<const Expr *> Args;
+};
+
+static const FindArgsResult findArgs(const CallExpr *Call);
+static std::vector<std::pair<int, int>>
+getCommentRanges(const std::string &source);
+static bool
+isPositionInComment(int position,
+                    const std::vector<std::pair<int, int>> &commentRanges);
+static void
+removeCharacterFromSource(std::string &FunctionCallSource,
+                          const std::vector<std::pair<int, int>> &CommentRanges,
+                          char Character, const CallExpr *InnerCall,
+                          std::vector<FixItHint> &Result, bool ReverseSearch);
+static SourceLocation
+getLocForEndOfToken(const Expr *expr, const MatchFinder::MatchResult &Match);
+static const std::vector<FixItHint>
+generateReplacement(const MatchFinder::MatchResult &Match,
+                    const CallExpr *TopCall, const FindArgsResult &Result);
+
+MinMaxUseInitializerListCheck::MinMaxUseInitializerListCheck(
+    StringRef Name, ClangTidyContext *Context)
+    : ClangTidyCheck(Name, Context),
+      Inserter(Options.getLocalOrGlobal("IncludeStyle",
+                                        utils::IncludeSorter::IS_LLVM),
+               areDiagsSelfContained()) {}
+
+void MinMaxUseInitializerListCheck::storeOptions(
+    ClangTidyOptions::OptionMap &Opts) {
+  Options.store(Opts, "IncludeStyle", Inserter.getStyle());
+}
+
+void MinMaxUseInitializerListCheck::registerMatchers(MatchFinder *Finder) {
+  auto CreateMatcher = [](const std::string &FunctionName) {
+    auto FuncDecl = functionDecl(hasName(FunctionName));
+    auto Expression = callExpr(callee(FuncDecl));
+
+    return callExpr(callee(FuncDecl),
+                    anyOf(hasArgument(0, Expression),
+                          hasArgument(1, Expression),
+                          hasArgument(0, cxxStdInitializerListExpr())),
+                    unless(hasParent(Expression)))
+        .bind("topCall");
+  };
+
+  Finder->addMatcher(CreateMatcher("::std::max"), this);
+  Finder->addMatcher(CreateMatcher("::std::min"), this);
+}
+
+void MinMaxUseInitializerListCheck::registerPPCallbacks(
+    const SourceManager &SM, Preprocessor *PP, Preprocessor *ModuleExpanderPP) {
+  Inserter.registerPreprocessor(PP);
+}
+
+void MinMaxUseInitializerListCheck::check(
+    const MatchFinder::MatchResult &Match) {
+
+  const auto *TopCall = Match.Nodes.getNodeAs<CallExpr>("topCall");
+
+  FindArgsResult Result = findArgs(TopCall);
+  const std::vector<FixItHint> Replacement =
+      generateReplacement(Match, TopCall, Result);
+
+  // if only changes are inserting '{' and '}' then ignore
+  if (Replacement.size() <= 2) {
+    return;
+  }
+
+  const DiagnosticBuilder Diagnostic =
+      diag(TopCall->getBeginLoc(),
+           "do not use nested 'std::%0' calls, use initializer lists instead")
+      << TopCall->getDirectCallee()->getName()
+      << Inserter.createIncludeInsertion(
+             Match.SourceManager->getFileID(TopCall->getBeginLoc()),
+             "<algorithm>");
+
+  for (const auto &FixIt : Replacement) {
+    Diagnostic << FixIt;
+  }
+}
+
+static const FindArgsResult findArgs(const CallExpr *Call) {
+  FindArgsResult Result;
+  Result.First = nullptr;
+  Result.Last = nullptr;
+  Result.Compare = nullptr;
+
+  if (Call->getNumArgs() == 3) {
+    auto ArgIterator = Call->arguments().begin();
+    std::advance(ArgIterator, 2);
+    Result.Compare = *ArgIterator;
+  } else {
+    auto ArgIterator = Call->arguments().begin();
+
+    if (const auto *InitListExpr =
+            dyn_cast<CXXStdInitializerListExpr>(*ArgIterator)) {
+      if (const auto *TempExpr =
+              dyn_cast<MaterializeTemporaryExpr>(InitListExpr->getSubExpr())) {
+        if (const auto *InitList =
+                dyn_cast<clang::InitListExpr>(TempExpr->getSubExpr())) {
+          for (const Expr *Init : InitList->inits()) {
+            Result.Args.push_back(Init);
+          }
+          Result.First = *ArgIterator;
+          Result.Last = *ArgIterator;
+
+          std::advance(ArgIterator, 1);
+          if (ArgIterator != Call->arguments().end()) {
+            Result.Compare = *ArgIterator;
+          }
+          return Result;
+        }
+      }
+    }
+  }
+
+  for (const Expr *Arg : Call->arguments()) {
+    if (!Result.First)
+      Result.First = Arg;
+
+    if (Arg == Result.Compare)
+      continue;
+
+    Result.Args.push_back(Arg);
+    Result.Last = Arg;
+  }
+
+  return Result;
+}
+
+static std::vector<std::pair<int, int>>
+getCommentRanges(const std::string &source) {
----------------
PiotrZSL wrote:

You do not need to parse comments.

https://github.com/llvm/llvm-project/pull/85572