[clang-tools-extra] Add new check: do not return 0; at the end of main() in C++ (PR #77586)
Bhuminjay Soni via cfe-commits
cfe-commits at lists.llvm.org
Wed Jan 10 03:25:11 PST 2024
https://github.com/11happy created https://github.com/llvm/llvm-project/pull/77586
**Overview:**
This pull request fixes #38469 where the issue proposes a new static analysis check in C++ to discourage the explicit return 0; statement at the end of the main() function. As C++ automatically assumes a return 0; in this context, having the explicit statement is redundant. The suggested change aims to enhance code readability by eliminating unnecessary lines in the main() function.
**Testing:**
- Tested the updated code.
- Verified that other functionalities remain unaffected.
**Dependencies:**
- No dependencies on other pull requests.
**CC:**
- @kirillbobyrev , @AaronBallman
>From bae95013cd7f937a5496cafcd40a77cc563addb0 Mon Sep 17 00:00:00 2001
From: 11happy <soni5happy at gmail.com>
Date: Wed, 10 Jan 2024 16:48:43 +0530
Subject: [PATCH] Added check for redundant return statement
Signed-off-by: 11happy <soni5happy at gmail.com>
---
.../clang-tidy/readability/CMakeLists.txt | 1 +
.../readability/DonotreturnzerocheckCheck.cpp | 54 +++++++++++++++++++
.../readability/DonotreturnzerocheckCheck.h | 30 +++++++++++
.../readability/ReadabilityTidyModule.cpp | 3 ++
clang-tools-extra/docs/ReleaseNotes.rst | 8 +++
.../docs/clang-tidy/checks/list.rst | 1 +
.../readability/DoNotReturnZeroCheck.rst | 25 +++++++++
.../readability/DoNotReturnZeroCheck.cpp | 8 +++
8 files changed, 130 insertions(+)
create mode 100644 clang-tools-extra/clang-tidy/readability/DonotreturnzerocheckCheck.cpp
create mode 100644 clang-tools-extra/clang-tidy/readability/DonotreturnzerocheckCheck.h
create mode 100644 clang-tools-extra/docs/clang-tidy/checks/readability/DoNotReturnZeroCheck.rst
create mode 100644 clang-tools-extra/test/clang-tidy/checkers/readability/DoNotReturnZeroCheck.cpp
diff --git a/clang-tools-extra/clang-tidy/readability/CMakeLists.txt b/clang-tools-extra/clang-tidy/readability/CMakeLists.txt
index 408c822b861c5f..cb7741d6f56ce7 100644
--- a/clang-tools-extra/clang-tidy/readability/CMakeLists.txt
+++ b/clang-tools-extra/clang-tidy/readability/CMakeLists.txt
@@ -14,6 +14,7 @@ add_clang_library(clangTidyReadabilityModule
ContainerSizeEmptyCheck.cpp
ConvertMemberFunctionsToStatic.cpp
DeleteNullPointerCheck.cpp
+ DonotreturnzerocheckCheck.cpp
DuplicateIncludeCheck.cpp
ElseAfterReturnCheck.cpp
FunctionCognitiveComplexityCheck.cpp
diff --git a/clang-tools-extra/clang-tidy/readability/DonotreturnzerocheckCheck.cpp b/clang-tools-extra/clang-tidy/readability/DonotreturnzerocheckCheck.cpp
new file mode 100644
index 00000000000000..66ea29be3c54a8
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/readability/DonotreturnzerocheckCheck.cpp
@@ -0,0 +1,54 @@
+//===--- DonotreturnzerocheckCheck.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 "DonotreturnzerocheckCheck.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+
+using namespace clang::ast_matchers;
+
+
+
+namespace clang::tidy::readability {
+ bool isCPlusPlusOrC99(const LangOptions &LangOpts) {
+ return LangOpts.CPlusPlus || LangOpts.C99;
+ }
+
+void DonotreturnzerocheckCheck::registerMatchers(MatchFinder *Finder) {
+ // FIXME: Add matchers.
+ Finder->addMatcher(functionDecl(
+ isMain(),returns(asString("int"))
+ ).bind("main"), this);
+}
+
+void DonotreturnzerocheckCheck::check(const MatchFinder::MatchResult &Result) {
+ // FIXME: Add callback implementation.
+ const auto *MatchedDecl = Result.Nodes.getNodeAs<FunctionDecl>("main");
+ if(isCPlusPlusOrC99(Result.Context->getLangOpts())){
+ SourceLocation ReturnLoc;
+ if (MatchedDecl->hasBody()) {
+ const CompoundStmt *Body = dyn_cast<CompoundStmt>(MatchedDecl->getBody());
+ if (Body && !Body->body_empty()) {
+ const Stmt *LastStmt = Body->body_back();
+ if (const auto *Return = dyn_cast<ReturnStmt>(LastStmt)) {
+ ReturnLoc = Return->getReturnLoc();
+ }
+ }
+ }
+
+ if (ReturnLoc.isValid()) {
+ // Suggest removal of the redundant return statement.
+ diag(ReturnLoc, "redundant 'return 0;' at the end of main")
+ << FixItHint::CreateRemoval(CharSourceRange::getTokenRange(ReturnLoc));
+ }
+
+ }
+
+}
+
+}
\ No newline at end of file
diff --git a/clang-tools-extra/clang-tidy/readability/DonotreturnzerocheckCheck.h b/clang-tools-extra/clang-tidy/readability/DonotreturnzerocheckCheck.h
new file mode 100644
index 00000000000000..1407b8c1831c9d
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/readability/DonotreturnzerocheckCheck.h
@@ -0,0 +1,30 @@
+//===--- DonotreturnzerocheckCheck.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_READABILITY_DONOTRETURNZEROCHECKCHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_DONOTRETURNZEROCHECKCHECK_H
+
+#include "../ClangTidyCheck.h"
+
+namespace clang::tidy::readability {
+
+/// FIXME: Write a short description.
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/readability/DoNotReturnZeroCheck.html
+class DonotreturnzerocheckCheck : public ClangTidyCheck {
+public:
+ DonotreturnzerocheckCheck(StringRef Name, ClangTidyContext *Context)
+ : ClangTidyCheck(Name, Context) {}
+ void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+ void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+};
+
+} // namespace clang::tidy::readability
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_DONOTRETURNZEROCHECKCHECK_H
diff --git a/clang-tools-extra/clang-tidy/readability/ReadabilityTidyModule.cpp b/clang-tools-extra/clang-tidy/readability/ReadabilityTidyModule.cpp
index 0b0aad7c0dcb36..3c3bc4fa94b97c 100644
--- a/clang-tools-extra/clang-tidy/readability/ReadabilityTidyModule.cpp
+++ b/clang-tools-extra/clang-tidy/readability/ReadabilityTidyModule.cpp
@@ -19,6 +19,7 @@
#include "ContainerSizeEmptyCheck.h"
#include "ConvertMemberFunctionsToStatic.h"
#include "DeleteNullPointerCheck.h"
+#include "DonotreturnzerocheckCheck.h"
#include "DuplicateIncludeCheck.h"
#include "ElseAfterReturnCheck.h"
#include "FunctionCognitiveComplexityCheck.h"
@@ -62,6 +63,8 @@ namespace readability {
class ReadabilityModule : public ClangTidyModule {
public:
void addCheckFactories(ClangTidyCheckFactories &CheckFactories) override {
+ CheckFactories.registerCheck<DonotreturnzerocheckCheck>(
+ "readability-DoNotReturnZeroCheck");
CheckFactories.registerCheck<AvoidConstParamsInDecls>(
"readability-avoid-const-params-in-decls");
CheckFactories.registerCheck<AvoidReturnWithVoidValueCheck>(
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index b4d87e0ed2a67a..cb45a135842576 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -224,6 +224,14 @@ New checks
Recommends the smallest possible underlying type for an ``enum`` or ``enum``
class based on the range of its enumerators.
+- New :doc:`readability-DoNotReturnZeroCheck
+ <clang-tidy/checks/readability/DoNotReturnZeroCheck>` check.
+
+ The readability-DoNotReturnZeroCheck clang-tidy check identifies
+ and suggests removal of redundant return 0; statements at the end of the main
+ function in C++ programs, enhancing code readability by eliminating unnecessary
+ code that is implicitly handled by modern C++ standards.
+
- New :doc:`readability-reference-to-constructed-temporary
<clang-tidy/checks/readability/reference-to-constructed-temporary>` check.
diff --git a/clang-tools-extra/docs/clang-tidy/checks/list.rst b/clang-tools-extra/docs/clang-tidy/checks/list.rst
index 2f86121ad87299..c0b1dfd05fcca0 100644
--- a/clang-tools-extra/docs/clang-tidy/checks/list.rst
+++ b/clang-tools-extra/docs/clang-tidy/checks/list.rst
@@ -336,6 +336,7 @@ Clang-Tidy Checks
:doc:`portability-restrict-system-includes <portability/restrict-system-includes>`, "Yes"
:doc:`portability-simd-intrinsics <portability/simd-intrinsics>`,
:doc:`portability-std-allocator-const <portability/std-allocator-const>`,
+ :doc:`readability-DoNotReturnZeroCheck <readability/DoNotReturnZeroCheck>`, "Yes"
:doc:`readability-avoid-const-params-in-decls <readability/avoid-const-params-in-decls>`, "Yes"
:doc:`readability-avoid-return-with-void-value <readability/avoid-return-with-void-value>`,
:doc:`readability-avoid-unconditional-preprocessor-if <readability/avoid-unconditional-preprocessor-if>`,
diff --git a/clang-tools-extra/docs/clang-tidy/checks/readability/DoNotReturnZeroCheck.rst b/clang-tools-extra/docs/clang-tidy/checks/readability/DoNotReturnZeroCheck.rst
new file mode 100644
index 00000000000000..3b6d0f86a3a1c6
--- /dev/null
+++ b/clang-tools-extra/docs/clang-tidy/checks/readability/DoNotReturnZeroCheck.rst
@@ -0,0 +1,25 @@
+.. title:: clang-tidy - readability-DoNotReturnZeroCheck
+
+readability-DoNotReturnZeroCheck
+================================
+
+This Check warns about redundant return statements returning zero.
+
+Before:
+
+.. code-block:: c++
+
+ int main(){
+ int a;
+ return 0;
+ }
+
+
+After:
+
+.. code-block:: c++
+
+ int main(){
+ int a;
+
+ }
diff --git a/clang-tools-extra/test/clang-tidy/checkers/readability/DoNotReturnZeroCheck.cpp b/clang-tools-extra/test/clang-tidy/checkers/readability/DoNotReturnZeroCheck.cpp
new file mode 100644
index 00000000000000..b2689e5eff907b
--- /dev/null
+++ b/clang-tools-extra/test/clang-tidy/checkers/readability/DoNotReturnZeroCheck.cpp
@@ -0,0 +1,8 @@
+// RUN: %check_clang_tidy %s readability-DoNotReturnZeroCheck %t
+
+
+int main() {
+ return 0; // Should trigger a warning.
+ // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: redundant 'return 0;' at the end of main [readability-DoNotReturnZeroCheck]
+ // CHECK-FIXES: {{^}}int main() {{{$}}
+}
\ No newline at end of file
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