[clang-tools-extra] [clang-tidy] Add new check `modernize-use-designated-initializers` (PR #80541)
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Sat Feb 3 05:27:50 PST 2024
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>
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-clang-tidy
@llvm/pr-subscribers-clang-tools-extra
Author: Danny Mösch (SimplyDanny)
<details>
<summary>Changes</summary>
Resolves #<!-- -->77618.
---
Full diff: https://github.com/llvm/llvm-project/pull/80541.diff
8 Files Affected:
- (modified) clang-tools-extra/clang-tidy/modernize/CMakeLists.txt (+1)
- (modified) clang-tools-extra/clang-tidy/modernize/ModernizeTidyModule.cpp (+3)
- (added) clang-tools-extra/clang-tidy/modernize/UseDesignatedInitializersCheck.cpp (+77)
- (added) clang-tools-extra/clang-tidy/modernize/UseDesignatedInitializersCheck.h (+42)
- (modified) clang-tools-extra/docs/ReleaseNotes.rst (+6)
- (modified) clang-tools-extra/docs/clang-tidy/checks/list.rst (+1)
- (added) clang-tools-extra/docs/clang-tidy/checks/modernize/use-designated-initializers.rst (+44)
- (added) clang-tools-extra/test/clang-tidy/checkers/modernize/use-designated-initializers.cpp (+48)
``````````diff
diff --git a/clang-tools-extra/clang-tidy/modernize/CMakeLists.txt b/clang-tools-extra/clang-tidy/modernize/CMakeLists.txt
index 28ca52f46943a..6852db6c2ee31 100644
--- a/clang-tools-extra/clang-tidy/modernize/CMakeLists.txt
+++ b/clang-tools-extra/clang-tidy/modernize/CMakeLists.txt
@@ -31,6 +31,7 @@ add_clang_library(clangTidyModernizeModule
UseBoolLiteralsCheck.cpp
UseConstraintsCheck.cpp
UseDefaultMemberInitCheck.cpp
+ UseDesignatedInitializersCheck.cpp
UseEmplaceCheck.cpp
UseEqualsDefaultCheck.cpp
UseEqualsDeleteCheck.cpp
diff --git a/clang-tools-extra/clang-tidy/modernize/ModernizeTidyModule.cpp b/clang-tools-extra/clang-tidy/modernize/ModernizeTidyModule.cpp
index 654f4bd0c6ba4..e96cf274f58cf 100644
--- a/clang-tools-extra/clang-tidy/modernize/ModernizeTidyModule.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/ModernizeTidyModule.cpp
@@ -32,6 +32,7 @@
#include "UseBoolLiteralsCheck.h"
#include "UseConstraintsCheck.h"
#include "UseDefaultMemberInitCheck.h"
+#include "UseDesignatedInitializersCheck.h"
#include "UseEmplaceCheck.h"
#include "UseEqualsDefaultCheck.h"
#include "UseEqualsDeleteCheck.h"
@@ -68,6 +69,8 @@ class ModernizeModule : public ClangTidyModule {
CheckFactories.registerCheck<MakeSharedCheck>("modernize-make-shared");
CheckFactories.registerCheck<MakeUniqueCheck>("modernize-make-unique");
CheckFactories.registerCheck<PassByValueCheck>("modernize-pass-by-value");
+ CheckFactories.registerCheck<UseDesignatedInitializersCheck>(
+ "modernize-use-designated-initializers");
CheckFactories.registerCheck<UseStartsEndsWithCheck>(
"modernize-use-starts-ends-with");
CheckFactories.registerCheck<UseStdNumbersCheck>(
diff --git a/clang-tools-extra/clang-tidy/modernize/UseDesignatedInitializersCheck.cpp b/clang-tools-extra/clang-tidy/modernize/UseDesignatedInitializersCheck.cpp
new file mode 100644
index 0000000000000..d269cef13e6aa
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/modernize/UseDesignatedInitializersCheck.cpp
@@ -0,0 +1,77 @@
+//===--- 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/Decl.h"
+#include "clang/AST/Expr.h"
+#include "clang/AST/Stmt.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/ASTMatchers/ASTMatchers.h"
+#include <algorithm>
+#include <iterator>
+#include <vector>
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::modernize {
+
+static constexpr auto IgnoreSingleElementAggregatesName =
+ "IgnoreSingleElementAggregates";
+static constexpr auto IgnoreSingleElementAggregatesDefault = true;
+
+static std::vector<Stmt *>
+getUndesignatedComponents(const InitListExpr *SyntacticInitList) {
+ std::vector<Stmt *> Result;
+ std::copy_if(SyntacticInitList->begin(), SyntacticInitList->end(),
+ std::back_inserter(Result),
+ [](auto S) { return !isa<DesignatedInitExpr>(S); });
+ return Result;
+}
+
+UseDesignatedInitializersCheck::UseDesignatedInitializersCheck(
+ StringRef Name, ClangTidyContext *Context)
+ : ClangTidyCheck(Name, Context),
+ IgnoreSingleElementAggregates(
+ Options.getLocalOrGlobal(IgnoreSingleElementAggregatesName,
+ IgnoreSingleElementAggregatesDefault)) {}
+
+void UseDesignatedInitializersCheck::registerMatchers(MatchFinder *Finder) {
+ Finder->addMatcher(
+ initListExpr(hasType(recordDecl().bind("type"))).bind("init"), this);
+}
+
+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 || !Type->isAggregate())
+ return;
+ if (IgnoreSingleElementAggregates && InitList->getNumInits() == 1)
+ return;
+ if (const auto *SyntacticInitList = InitList->getSyntacticForm()) {
+ const auto UndesignatedComponents =
+ getUndesignatedComponents(SyntacticInitList);
+ if (UndesignatedComponents.empty())
+ return;
+ if (UndesignatedComponents.size() == SyntacticInitList->getNumInits()) {
+ diag(InitList->getLBraceLoc(), "use designated initializer list");
+ return;
+ }
+ for (const auto *InitExpr : UndesignatedComponents) {
+ diag(InitExpr->getBeginLoc(), "use designated init expression");
+ }
+ }
+}
+
+void UseDesignatedInitializersCheck::storeOptions(
+ ClangTidyOptions::OptionMap &Opts) {
+ Options.store(Opts, IgnoreSingleElementAggregatesName,
+ IgnoreSingleElementAggregates);
+}
+
+} // namespace clang::tidy::modernize
diff --git a/clang-tools-extra/clang-tidy/modernize/UseDesignatedInitializersCheck.h b/clang-tools-extra/clang-tidy/modernize/UseDesignatedInitializersCheck.h
new file mode 100644
index 0000000000000..34290aba06fab
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/modernize/UseDesignatedInitializersCheck.h
@@ -0,0 +1,42 @@
+//===--- UseDesignatedInitializersCheck.h - clang-tidy ----------*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MODERNIZE_USEDESIGNATEDINITIALIZERSCHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MODERNIZE_USEDESIGNATEDINITIALIZERSCHECK_H
+
+#include "../ClangTidyCheck.h"
+
+namespace clang::tidy::modernize {
+
+/// Triggers on initializer lists for aggregate type that could be
+/// written as designated initializers instead.
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/modernize/use-designated-initializers.html
+class UseDesignatedInitializersCheck : public ClangTidyCheck {
+public:
+ UseDesignatedInitializersCheck(StringRef Name, ClangTidyContext *Context);
+ void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+ void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+
+private:
+ std::optional<TraversalKind> getCheckTraversalKind() const override {
+ return TK_IgnoreUnlessSpelledInSource;
+ }
+ bool isLanguageVersionSupported(const LangOptions &LangOpts) const override {
+ return LangOpts.CPlusPlus20;
+ }
+ void storeOptions(ClangTidyOptions::OptionMap &Opts) override;
+
+private:
+ bool IgnoreSingleElementAggregates;
+};
+
+} // namespace clang::tidy::modernize
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MODERNIZE_USEDESIGNATEDINITIALIZERSCHECK_H
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index 9e819ea34c397..ce86f2ea455ff 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -100,6 +100,12 @@ Improvements to clang-tidy
New checks
^^^^^^^^^^
+- New :doc:`modernize-use-designated-initializers
+ <clang-tidy/checks/modernize/use-designated-initializers>` check.
+
+ Triggers on initializer lists for aggregate type that could be
+ written as designated initializers instead.
+
New check aliases
^^^^^^^^^^^^^^^^^
diff --git a/clang-tools-extra/docs/clang-tidy/checks/list.rst b/clang-tools-extra/docs/clang-tidy/checks/list.rst
index f40192ed9dea2..5d3b99e0996c2 100644
--- a/clang-tools-extra/docs/clang-tidy/checks/list.rst
+++ b/clang-tools-extra/docs/clang-tidy/checks/list.rst
@@ -287,6 +287,7 @@ Clang-Tidy Checks
:doc:`modernize-use-bool-literals <modernize/use-bool-literals>`, "Yes"
:doc:`modernize-use-constraints <modernize/use-constraints>`, "Yes"
:doc:`modernize-use-default-member-init <modernize/use-default-member-init>`, "Yes"
+ :doc:`modernize-use-designated-initializers <modernize/use-designated-initializers>`, "Yes"
:doc:`modernize-use-emplace <modernize/use-emplace>`, "Yes"
:doc:`modernize-use-equals-default <modernize/use-equals-default>`, "Yes"
:doc:`modernize-use-equals-delete <modernize/use-equals-delete>`, "Yes"
diff --git a/clang-tools-extra/docs/clang-tidy/checks/modernize/use-designated-initializers.rst b/clang-tools-extra/docs/clang-tidy/checks/modernize/use-designated-initializers.rst
new file mode 100644
index 0000000000000..1e182218dbd8e
--- /dev/null
+++ b/clang-tools-extra/docs/clang-tidy/checks/modernize/use-designated-initializers.rst
@@ -0,0 +1,44 @@
+.. title:: clang-tidy - modernize-use-designated-initializers
+
+modernize-use-designated-initializers
+=====================================
+
+Triggers on initializer lists for aggregate type that could be written as
+designated initializers instead.
+
+With plain initializer lists, it is very easy to introduce bugs when adding
+new fields in the middle of a struct or class type. The same confusion might
+arise when changing the order of fields.
+
+C++ 20 supports the designated initializer syntax for aggregate types.
+By applying it, we can always be sure that aggregates are constructed correctly,
+because the every variable being initialized is referenced by name.
+
+Example:
+
+.. code-block::
+
+ struct S { int i, j; };
+
+is an aggregate type that should be initialized as
+
+.. code-block::
+
+ S s{.i = 1, .j = 2};
+
+instead of
+
+.. code-block::
+
+ S s{1, 2};
+
+which could easily become an issue when ``i`` and ``j`` are swapped in the
+declaration of ``S``.
+
+Options
+-------
+
+.. options:: IgnoreSingleElementAggregates
+
+ The value `false` specifies that even initializers for aggregate types
+ with only a single element should be checked. The default value is `true`.
diff --git a/clang-tools-extra/test/clang-tidy/checkers/modernize/use-designated-initializers.cpp b/clang-tools-extra/test/clang-tidy/checkers/modernize/use-designated-initializers.cpp
new file mode 100644
index 0000000000000..d932e2d5e4863
--- /dev/null
+++ b/clang-tools-extra/test/clang-tidy/checkers/modernize/use-designated-initializers.cpp
@@ -0,0 +1,48 @@
+// RUN: %check_clang_tidy -std=c++20 %s modernize-use-designated-initializers %t
+// RUN: %check_clang_tidy -check-suffixes=,SINGLE-ELEMENT -std=c++20 %s modernize-use-designated-initializers %t \
+// RUN: -- -config="{CheckOptions: [{key: modernize-use-designated-initializers.IgnoreSingleElementAggregates, value: false}]}" \
+// RUN: --
+
+struct S1 {};
+
+S1 s11{};
+S1 s12 = {};
+S1 s13();
+S1 s14;
+
+struct S2 { int i, j; };
+
+S2 s21{.i=1, .j =2};
+
+S2 s22 = {1, 2};
+// CHECK-MESSAGES: :[[@LINE-1]]:10: warning: use designated initializer list [modernize-use-designated-initializers]
+
+S2 s23{1};
+// CHECK-MESSAGES: :[[@LINE-1]]:7: warning: use designated initializer list [modernize-use-designated-initializers]
+
+S2 s24{.i = 1};
+
+S2 s25 = {.i=1, 2};
+// CHECK-MESSAGES: :[[@LINE-1]]:17: warning: use designated init expression [modernize-use-designated-initializers]
+
+class S3 {
+ public:
+ S2 s2;
+ double d;
+};
+
+S3 s31 = {.s2 = 1, 2, 3.1};
+// CHECK-MESSAGES: :[[@LINE-1]]:20: warning: use designated init expression [modernize-use-designated-initializers]
+// CHECK-MESSAGES: :[[@LINE-2]]:23: warning: use designated init expression [modernize-use-designated-initializers]
+
+S3 s32 = {{.i = 1, 2}};
+// CHECK-MESSAGES: :[[@LINE-1]]:10: warning: use designated initializer list [modernize-use-designated-initializers]
+// CHECK-MESSAGES: :[[@LINE-2]]:20: warning: use designated init expression [modernize-use-designated-initializers]
+
+struct S4 {
+ double d;
+ private: static int i;
+};
+
+S4 s41 {2.2};
+// CHECK-MESSAGES-SINGLE-ELEMENT: :[[@LINE-1]]:8: warning: use designated initializer list [modernize-use-designated-initializers]
``````````
</details>
https://github.com/llvm/llvm-project/pull/80541
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