[clang] [clang-tools-extra] [clang-tidy] Add new check `modernize-use-designated-initializers` (PR #80541)

[Piotr Zegar via cfe-commits]

Danny =?utf-8?q?Mösch?= <danny.moesch at icloud.com>,
Danny =?utf-8?q?Mösch?= <danny.moesch at icloud.com>,
Danny =?utf-8?q?Mösch?= <danny.moesch at icloud.com>,
Danny =?utf-8?q?Mösch?= <danny.moesch at icloud.com>,
Danny =?utf-8?q?Mösch?= <danny.moesch at icloud.com>,
Danny =?utf-8?q?Mösch?= <danny.moesch at icloud.com>,
Danny =?utf-8?q?Mösch?= <danny.moesch at icloud.com>,
Danny =?utf-8?q?Mösch?= <danny.moesch at icloud.com>,
Danny =?utf-8?q?Mösch?= <danny.moesch at icloud.com>,
Danny =?utf-8?q?Mösch?= <danny.moesch at icloud.com>,
Danny =?utf-8?q?Mösch?= <danny.moesch at icloud.com>,
Danny =?utf-8?q?Mösch?= <danny.moesch at icloud.com>,
Danny =?utf-8?q?Mösch?= <danny.moesch at icloud.com>,
Danny =?utf-8?q?Mösch?= <danny.moesch at icloud.com>,
Danny =?utf-8?q?Mösch?= <danny.moesch at icloud.com>,
Danny =?utf-8?q?Mösch?= <danny.moesch at icloud.com>,
Danny =?utf-8?q?Mösch?= <danny.moesch at icloud.com>,
Danny =?utf-8?q?Mösch?= <danny.moesch at icloud.com>,
Danny =?utf-8?q?Mösch?= <danny.moesch at icloud.com>,
Danny =?utf-8?q?Mösch?= <danny.moesch at icloud.com>,
Danny =?utf-8?q?Mösch?= <danny.moesch at icloud.com>,
Danny =?utf-8?q?Mösch?= <danny.moesch at icloud.com>,
Danny =?utf-8?q?Mösch?= <danny.moesch at icloud.com>,
Danny =?utf-8?q?Mösch?= <danny.moesch at icloud.com>,
Danny =?utf-8?q?Mösch?= <danny.moesch at icloud.com>,
Danny =?utf-8?q?Mösch?= <danny.moesch at icloud.com>,
Danny =?utf-8?q?Mösch?= <danny.moesch at icloud.com>,
Danny =?utf-8?q?Mösch?= <danny.moesch at icloud.com>,
Danny =?utf-8?q?Mösch?= <danny.moesch at icloud.com>,
Danny =?utf-8?q?Mösch?= <danny.moesch at icloud.com>,
Danny =?utf-8?q?Mösch?= <danny.moesch at icloud.com>,
Danny =?utf-8?q?Mösch?= <danny.moesch at icloud.com>,
Danny =?utf-8?q?Mösch?= <danny.moesch at icloud.com>,
Danny =?utf-8?q?Mösch?= <danny.moesch at icloud.com>,
Danny =?utf-8?q?Mösch?= <danny.moesch at icloud.com>,
Danny =?utf-8?q?Mösch?= <danny.moesch at icloud.com>,
Danny =?utf-8?q?Mösch?= <danny.moesch at icloud.com>,
Danny =?utf-8?q?Mösch?= <danny.moesch at icloud.com>,
Danny =?utf-8?q?Mösch?= <danny.moesch at icloud.com>,
Danny =?utf-8?q?Mösch?= <danny.moesch at icloud.com>,
Danny =?utf-8?q?Mösch?= <danny.moesch at icloud.com>,
Danny =?utf-8?q?Mösch?= <danny.moesch at icloud.com>,
Danny =?utf-8?q?Mösch?= <danny.moesch at icloud.com>
Message-ID:
In-Reply-To: <llvm.org/llvm/llvm-project/pull/80541 at github.com>


================
@@ -0,0 +1,132 @@
+//===--- UseDesignatedInitializersCheck.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 "UseDesignatedInitializersCheck.h"
+#include "clang/AST/APValue.h"
+#include "clang/AST/Decl.h"
+#include "clang/AST/Expr.h"
+#include "clang/AST/Stmt.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/ASTMatchers/ASTMatchers.h"
+#include "clang/ASTMatchers/ASTMatchersMacros.h"
+#include "clang/Basic/Diagnostic.h"
+#include "clang/Lex/Lexer.h"
+#include "clang/Tooling/DesignatedInitializers.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::modernize {
+
+static constexpr char IgnoreSingleElementAggregatesName[] =
+    "IgnoreSingleElementAggregates";
+static constexpr bool IgnoreSingleElementAggregatesDefault = true;
+
+static constexpr char RestrictToPODTypesName[] = "RestrictToPODTypes";
+static constexpr bool RestrictToPODTypesDefault = false;
+
+static constexpr char IgnoreMacrosName[] = "IgnoreMacros";
+static constexpr bool IgnoreMacrosDefault = true;
+
+namespace {
+
+AST_MATCHER(CXXRecordDecl, isAggregate) { return Node.isAggregate(); }
+
+AST_MATCHER(CXXRecordDecl, isPOD) { return Node.isPOD(); }
+
+AST_MATCHER(InitListExpr, isFullyDesignated) {
+  if (const InitListExpr *SyntacticForm =
+          Node.isSyntacticForm() ? &Node : Node.getSyntacticForm()) {
+    return llvm::all_of(SyntacticForm->children(), [](auto *InitExpr) {
+      return isa<DesignatedInitExpr>(InitExpr);
+    });
+  }
+  return true;
+}
+
+AST_MATCHER(InitListExpr, hasSingleElement) { return Node.getNumInits() == 1; }
+
+} // namespace
+
+UseDesignatedInitializersCheck::UseDesignatedInitializersCheck(
+    StringRef Name, ClangTidyContext *Context)
+    : ClangTidyCheck(Name, Context), IgnoreSingleElementAggregates(Options.get(
+                                         IgnoreSingleElementAggregatesName,
+                                         IgnoreSingleElementAggregatesDefault)),
+      RestrictToPODTypes(
+          Options.get(RestrictToPODTypesName, RestrictToPODTypesDefault)),
+      IgnoreMacros(Options.get(IgnoreMacrosName, IgnoreMacrosDefault)) {}
+
+void UseDesignatedInitializersCheck::registerMatchers(MatchFinder *Finder) {
+  const auto HasBaseWithFields =
+      hasAnyBase(hasType(cxxRecordDecl(has(fieldDecl()))));
+  Finder->addMatcher(
+      initListExpr(
+          hasType(cxxRecordDecl(RestrictToPODTypes ? isPOD() : isAggregate(),
+                                unless(HasBaseWithFields))
+                      .bind("type")),
+          unless(IgnoreSingleElementAggregates ? hasSingleElement()
+                                               : unless(anything())),
+          unless(isFullyDesignated()))
+          .bind("init"),
+      this);
+}
+
+static bool isFullyUndesignated(const InitListExpr *SyntacticInitList) {
+  return std::all_of(
+      SyntacticInitList->begin(), SyntacticInitList->end(),
+      [](auto *InitExpr) { return !isa<DesignatedInitExpr>(InitExpr); });
+}
+
+void UseDesignatedInitializersCheck::check(
+    const MatchFinder::MatchResult &Result) {
+  const auto *InitList = Result.Nodes.getNodeAs<InitListExpr>("init");
+  const auto *Type = Result.Nodes.getNodeAs<CXXRecordDecl>("type");
+  if (!Type || !InitList)
+    return;
+  if (const auto *SyntacticInitList = InitList->getSyntacticForm()) {
+    const llvm::DenseMap<clang::SourceLocation, std::string> Designators =
+        clang::tooling::getUnwrittenDesignators(SyntacticInitList);
+    if (isFullyUndesignated(SyntacticInitList)) {
+      if (IgnoreMacros && InitList->getBeginLoc().isMacroID()) {
+        return;
+      }
+      DiagnosticBuilder Diag =
+          diag(InitList->getLBraceLoc(), "use designated initializer list");
----------------
PiotrZSL wrote:

consider adding record name: "use designated initializer list to initialize 'SomeClassName'".
and diagnostic note that would point to that record. after this diag (make sure that 2 diag are not created at once, use scope)

https://github.com/llvm/llvm-project/pull/80541