[clang-tidy] add readability-redundant-parentheses (#159911)

This check wants to detect a common happened case that forgetting to
remove parenthese during modifying code.

---------

Co-authored-by: Victor Chernyakin <chernyakin.victor.j@outlook.com>
Co-authored-by: Baranov Victor <bar.victor.2002@gmail.com>

Author: 3 people

clang-tools-extra/clang-tidy/readability/CMakeLists.txt

@@ -44,6 +44,7 @@ add_clang_library(clangTidyReadabilityModule STATIC
   RedundantDeclarationCheck.cpp
   RedundantFunctionPtrDereferenceCheck.cpp
   RedundantMemberInitCheck.cpp
+  RedundantParenthesesCheck.cpp
   RedundantPreprocessorCheck.cpp
   RedundantSmartptrGetCheck.cpp
   RedundantStringCStrCheck.cpp

clang-tools-extra/clang-tidy/readability/ReadabilityTidyModule.cpp

@@ -47,6 +47,7 @@
 #include "RedundantFunctionPtrDereferenceCheck.h"
 #include "RedundantInlineSpecifierCheck.h"
 #include "RedundantMemberInitCheck.h"
+#include "RedundantParenthesesCheck.h"
 #include "RedundantPreprocessorCheck.h"
 #include "RedundantSmartptrGetCheck.h"
 #include "RedundantStringCStrCheck.h"
@@ -138,6 +139,8 @@ class ReadabilityModule : public ClangTidyModule {
         "readability-redundant-function-ptr-dereference");
     CheckFactories.registerCheck<RedundantMemberInitCheck>(
         "readability-redundant-member-init");
+    CheckFactories.registerCheck<RedundantParenthesesCheck>(
+        "readability-redundant-parentheses");
     CheckFactories.registerCheck<RedundantPreprocessorCheck>(
         "readability-redundant-preprocessor");
     CheckFactories.registerCheck<ReferenceToConstructedTemporaryCheck>(

clang-tools-extra/clang-tidy/readability/RedundantParenthesesCheck.cpp

@@ -0,0 +1,55 @@
+//===----------------------------------------------------------------------===//
+//
+// 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 "RedundantParenthesesCheck.h"
+#include "clang/AST/Expr.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/ASTMatchers/ASTMatchers.h"
+#include "clang/ASTMatchers/ASTMatchersMacros.h"
+#include <cassert>
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::readability {
+
+namespace {
+
+AST_MATCHER_P(ParenExpr, subExpr, ast_matchers::internal::Matcher<Expr>,
+              InnerMatcher) {
+  return InnerMatcher.matches(*Node.getSubExpr(), Finder, Builder);
+}
+
+AST_MATCHER(ParenExpr, isInMacro) {
+  const Expr *E = Node.getSubExpr();
+  return Node.getLParen().isMacroID() || Node.getRParen().isMacroID() ||
+         E->getBeginLoc().isMacroID() || E->getEndLoc().isMacroID();
+}
+
+} // namespace
+
+void RedundantParenthesesCheck::registerMatchers(MatchFinder *Finder) {
+  const auto ConstantExpr =
+      expr(anyOf(integerLiteral(), floatLiteral(), characterLiteral(),
+                 cxxBoolLiteral(), stringLiteral(), cxxNullPtrLiteralExpr()));
+  Finder->addMatcher(
+      parenExpr(subExpr(anyOf(parenExpr(), ConstantExpr, declRefExpr())),
+                unless(anyOf(isInMacro(),
+                             // sizeof(...) is common used.
+                             hasParent(unaryExprOrTypeTraitExpr()))))
+          .bind("dup"),
+      this);
+}
+
+void RedundantParenthesesCheck::check(const MatchFinder::MatchResult &Result) {
+  const auto *PE = Result.Nodes.getNodeAs<ParenExpr>("dup");
+  diag(PE->getBeginLoc(), "redundant parentheses around expression")
+      << FixItHint::CreateRemoval(PE->getLParen())
+      << FixItHint::CreateRemoval(PE->getRParen());
+}
+
+} // namespace clang::tidy::readability

clang-tools-extra/clang-tidy/readability/RedundantParenthesesCheck.h

@@ -0,0 +1,34 @@
+//===----------------------------------------------------------------------===//
+//
+// 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_REDUNDANTPARENTHESESCHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_REDUNDANTPARENTHESESCHECK_H
+
+#include "../ClangTidyCheck.h"
+#include "clang/Basic/LangOptions.h"
+
+namespace clang::tidy::readability {
+
+/// Detect redundant parentheses.
+///
+/// For the user-facing documentation see:
+/// https://clang.llvm.org/extra/clang-tidy/checks/readability/redundant-parentheses.html
+class RedundantParenthesesCheck : public ClangTidyCheck {
+public:
+  RedundantParenthesesCheck(StringRef Name, ClangTidyContext *Context)
+      : ClangTidyCheck(Name, Context) {}
+  void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+  void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+  bool isLanguageVersionSupported(const LangOptions &LangOpts) const override {
+    return LangOpts.CPlusPlus | LangOpts.C99;
+  }
+};
+
+} // namespace clang::tidy::readability
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_REDUNDANTPARENTHESESCHECK_H

clang-tools-extra/docs/ReleaseNotes.rst

@@ -203,6 +203,11 @@ New checks
   Finds virtual function overrides with different visibility than the function
   in the base class.
 
+- New :doc:`readability-redundant-parentheses
+  <clang-tidy/checks/readability/redundant-parentheses>` check.
+
+  Detect redundant parentheses.
+
 New check aliases
 ^^^^^^^^^^^^^^^^^
 

clang-tools-extra/docs/clang-tidy/checks/list.rst

@@ -404,6 +404,7 @@ Clang-Tidy Checks
    :doc:`readability-redundant-function-ptr-dereference <readability/redundant-function-ptr-dereference>`, "Yes"
    :doc:`readability-redundant-inline-specifier <readability/redundant-inline-specifier>`, "Yes"
    :doc:`readability-redundant-member-init <readability/redundant-member-init>`, "Yes"
+   :doc:`readability-redundant-parentheses <readability/redundant-parentheses>`, "Yes"
    :doc:`readability-redundant-preprocessor <readability/redundant-preprocessor>`,
    :doc:`readability-redundant-smartptr-get <readability/redundant-smartptr-get>`, "Yes"
    :doc:`readability-redundant-string-cstr <readability/redundant-string-cstr>`, "Yes"

clang-tools-extra/docs/clang-tidy/checks/readability/redundant-parentheses.rst

@@ -0,0 +1,29 @@
+.. title:: clang-tidy - readability-redundant-parentheses
+
+readability-redundant-parentheses
+=================================
+
+Detect redundant parentheses.
+
+When modifying code, one often forgets to remove the corresponding parentheses.
+This results in overly lengthy code. When the expression is complex, finding
+the matching parentheses becomes particularly difficult.
+
+Example
+-------
+
+.. code-block:: c++
+
+  (1);
+  ((a + 2)) * 3;
+  (a);
+  ("aaa");
+
+Currently this check does not take into account the precedence of operations.
+Even if the expression within the parentheses has a higher priority than that
+outside the parentheses. In other words, removing the parentheses will not
+affect the semantics.
+
+.. code-block:: c++
+
+  int a = (1 * 2) + 3; // no warning

clang-tools-extra/test/clang-tidy/checkers/readability/redundant-parentheses.cpp

@@ -0,0 +1,64 @@
+// RUN: %check_clang_tidy %s readability-redundant-parentheses %t
+
+void parenExpr() {
+  1 + 1;
+  (1 + 1);
+  ((1 + 1));
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: redundant parentheses around expression [readability-redundant-parentheses]
+  // CHECK-FIXES:    (1 + 1);
+  (((1 + 1)));
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: redundant parentheses around expression [readability-redundant-parentheses]
+  // CHECK-MESSAGES: :[[@LINE-2]]:4: warning: redundant parentheses around expression [readability-redundant-parentheses]
+  // CHECK-FIXES:    (1 + 1);
+  ((((1 + 1))));
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: redundant parentheses around expression [readability-redundant-parentheses]
+  // CHECK-MESSAGES: :[[@LINE-2]]:4: warning: redundant parentheses around expression [readability-redundant-parentheses]
+  // CHECK-MESSAGES: :[[@LINE-3]]:5: warning: redundant parentheses around expression [readability-redundant-parentheses]
+  // CHECK-FIXES:    (1 + 1);
+}
+
+#define EXP (1 + 1)
+#define PAREN(e) (e)
+void parenExprWithMacro() {
+  EXP; // 1
+  (EXP); // 2
+  ((EXP)); // 3
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: redundant parentheses around expression [readability-redundant-parentheses]
+  // CHECK-FIXES:    (EXP); // 3
+  PAREN((1));
+}
+
+void constant() {
+  (1);
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: redundant parentheses around expression [readability-redundant-parentheses]
+  // CHECK-FIXES:    1;
+  (1.0);
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: redundant parentheses around expression [readability-redundant-parentheses]
+  // CHECK-FIXES:    1.0;
+  (true);
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: redundant parentheses around expression [readability-redundant-parentheses]
+  // CHECK-FIXES:    true;
+  (',');
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: redundant parentheses around expression [readability-redundant-parentheses]
+  // CHECK-FIXES:    ',';
+  ("v4");
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: redundant parentheses around expression [readability-redundant-parentheses]
+  // CHECK-FIXES:    "v4";
+  (nullptr);
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: redundant parentheses around expression [readability-redundant-parentheses]
+  // CHECK-FIXES:    nullptr;
+}
+
+void declRefExpr(int a) {
+  (a);
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: redundant parentheses around expression [readability-redundant-parentheses]
+  // CHECK-FIXES:    a;
+}
+
+void exceptions() {
+  sizeof(1);
+  alignof(2);
+  alignof((3));
+  // CHECK-MESSAGES: :[[@LINE-1]]:11: warning: redundant parentheses around expression [readability-redundant-parentheses]
+  // CHECK-FIXES:    alignof(3);
+}