From 399a50cf356f4881cbab46a95d2c9efed18454ba Mon Sep 17 00:00:00 2001 From: Daniel Marjamaki Date: Tue, 1 Nov 2016 13:26:15 +0000 Subject: [PATCH] [clang-tidy] Add check readability-redundant-declaration Finds redundant variable and function declarations. extern int X; extern int X; // <- redundant Differential Revision: https://reviews.llvm.org/D24656 llvm-svn: 285689 --- .../clang-tidy/readability/CMakeLists.txt | 1 + .../readability/ReadabilityTidyModule.cpp | 3 + .../readability/RedundantDeclarationCheck.cpp | 71 ++++++++++++++++++++++ .../readability/RedundantDeclarationCheck.h | 35 +++++++++++ clang-tools-extra/docs/ReleaseNotes.rst | 5 ++ clang-tools-extra/docs/clang-tidy/checks/list.rst | 1 + .../checks/readability-redundant-declaration.rst | 27 ++++++++ .../readability-redundant-declaration.cpp | 23 +++++++ 8 files changed, 166 insertions(+) create mode 100644 clang-tools-extra/clang-tidy/readability/RedundantDeclarationCheck.cpp create mode 100644 clang-tools-extra/clang-tidy/readability/RedundantDeclarationCheck.h create mode 100644 clang-tools-extra/docs/clang-tidy/checks/readability-redundant-declaration.rst create mode 100644 clang-tools-extra/test/clang-tidy/readability-redundant-declaration.cpp diff --git a/clang-tools-extra/clang-tidy/readability/CMakeLists.txt b/clang-tools-extra/clang-tidy/readability/CMakeLists.txt index e0d532d..efbe49e 100644 --- a/clang-tools-extra/clang-tidy/readability/CMakeLists.txt +++ b/clang-tools-extra/clang-tidy/readability/CMakeLists.txt @@ -16,6 +16,7 @@ add_clang_library(clangTidyReadabilityModule NonConstParameterCheck.cpp ReadabilityTidyModule.cpp RedundantControlFlowCheck.cpp + RedundantDeclarationCheck.cpp RedundantMemberInitCheck.cpp RedundantStringCStrCheck.cpp RedundantSmartptrGetCheck.cpp diff --git a/clang-tools-extra/clang-tidy/readability/ReadabilityTidyModule.cpp b/clang-tools-extra/clang-tidy/readability/ReadabilityTidyModule.cpp index 0b6508a..285826b 100644 --- a/clang-tools-extra/clang-tidy/readability/ReadabilityTidyModule.cpp +++ b/clang-tools-extra/clang-tidy/readability/ReadabilityTidyModule.cpp @@ -23,6 +23,7 @@ #include "NamedParameterCheck.h" #include "NonConstParameterCheck.h" #include "RedundantControlFlowCheck.h" +#include "RedundantDeclarationCheck.h" #include "RedundantMemberInitCheck.h" #include "RedundantSmartptrGetCheck.h" #include "RedundantStringCStrCheck.h" @@ -68,6 +69,8 @@ public: "readability-non-const-parameter"); CheckFactories.registerCheck( "readability-redundant-control-flow"); + CheckFactories.registerCheck( + "readability-redundant-declaration"); CheckFactories.registerCheck( "readability-redundant-smartptr-get"); CheckFactories.registerCheck( diff --git a/clang-tools-extra/clang-tidy/readability/RedundantDeclarationCheck.cpp b/clang-tools-extra/clang-tidy/readability/RedundantDeclarationCheck.cpp new file mode 100644 index 0000000..44aa7a5 --- /dev/null +++ b/clang-tools-extra/clang-tidy/readability/RedundantDeclarationCheck.cpp @@ -0,0 +1,71 @@ +//===--- RedundantDeclarationCheck.cpp - clang-tidy------------------------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// + +#include "RedundantDeclarationCheck.h" +#include "clang/AST/ASTContext.h" +#include "clang/ASTMatchers/ASTMatchFinder.h" +#include "clang/Lex/Lexer.h" + +using namespace clang::ast_matchers; + +namespace clang { +namespace tidy { +namespace readability { + +void RedundantDeclarationCheck::registerMatchers(MatchFinder *Finder) { + Finder->addMatcher(namedDecl(anyOf(varDecl(), functionDecl())).bind("Decl"), this); +} + +void RedundantDeclarationCheck::check(const MatchFinder::MatchResult &Result) { + const NamedDecl *D = Result.Nodes.getNodeAs("Decl"); + const auto *Prev = D->getPreviousDecl(); + if (!Prev) + return; + if (Prev->getLocation() == D->getLocation()) + return; + + const SourceManager &SM = *Result.SourceManager; + + const bool DifferentHeaders = + !SM.isInMainFile(D->getLocation()) && + !SM.isWrittenInSameFile(Prev->getLocation(), D->getLocation()); + + bool MultiVar = false; + if (const auto *VD = dyn_cast(D)) { + if (VD->getPreviousDecl()->getStorageClass() == SC_Extern && + VD->getStorageClass() != SC_Extern) + return; + // Is this a multivariable declaration? + for (const auto Other : VD->getDeclContext()->decls()) { + if (Other != D && Other->getLocStart() == VD->getLocStart()) { + MultiVar = true; + break; + } + } + } else { + const auto *FD = cast(D); + if (FD->isThisDeclarationADefinition()) + return; + } + + SourceLocation EndLoc = Lexer::getLocForEndOfToken( + D->getSourceRange().getEnd(), 0, SM, Result.Context->getLangOpts()); + { + auto Diag = diag(D->getLocation(), "redundant %0 declaration") + << D; + if (!MultiVar && !DifferentHeaders) + Diag << FixItHint::CreateRemoval( + SourceRange(D->getSourceRange().getBegin(), EndLoc)); + } + diag(Prev->getLocation(), "previously declared here", DiagnosticIDs::Note); +} + +} // namespace readability +} // namespace tidy +} // namespace clang diff --git a/clang-tools-extra/clang-tidy/readability/RedundantDeclarationCheck.h b/clang-tools-extra/clang-tidy/readability/RedundantDeclarationCheck.h new file mode 100644 index 0000000..96c4830 --- /dev/null +++ b/clang-tools-extra/clang-tidy/readability/RedundantDeclarationCheck.h @@ -0,0 +1,35 @@ +//===--- RedundantDeclarationCheck.h - clang-tidy----------------*- C++ -*-===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// + +#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_REDUNDANT_DECLARATION_H +#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_REDUNDANT_DECLARATION_H + +#include "../ClangTidy.h" + +namespace clang { +namespace tidy { +namespace readability { + +/// Find redundant variable declarations. +/// +/// For the user-facing documentation see: +/// http://clang.llvm.org/extra/clang-tidy/checks/readability-redundant-declaration.html +class RedundantDeclarationCheck : public ClangTidyCheck { +public: + RedundantDeclarationCheck(StringRef Name, ClangTidyContext *Context) + : ClangTidyCheck(Name, Context) {} + void registerMatchers(ast_matchers::MatchFinder *Finder) override; + void check(const ast_matchers::MatchFinder::MatchResult &Result) override; +}; + +} // namespace readability +} // namespace tidy +} // namespace clang + +#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_REDUNDANT_DECLARATION_H diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst index 8e01470..98da810 100644 --- a/clang-tools-extra/docs/ReleaseNotes.rst +++ b/clang-tools-extra/docs/ReleaseNotes.rst @@ -129,6 +129,11 @@ Improvements to clang-tidy Flags member initializations that are unnecessary because the same default constructor would be called if they were not present. +- New `readability-redundant-declaration + `_ check + + Warns about duplicate variable declarations. + Fixed bugs: - `modernize-make-unique diff --git a/clang-tools-extra/docs/clang-tidy/checks/list.rst b/clang-tools-extra/docs/clang-tidy/checks/list.rst index ba66c9d..f973235 100644 --- a/clang-tools-extra/docs/clang-tidy/checks/list.rst +++ b/clang-tools-extra/docs/clang-tidy/checks/list.rst @@ -133,6 +133,7 @@ Clang-Tidy Checks readability-named-parameter readability-non-const-parameter readability-redundant-control-flow + readability-redundant-declaration readability-redundant-member-init readability-redundant-smartptr-get readability-redundant-string-cstr diff --git a/clang-tools-extra/docs/clang-tidy/checks/readability-redundant-declaration.rst b/clang-tools-extra/docs/clang-tidy/checks/readability-redundant-declaration.rst new file mode 100644 index 0000000..032feb4 --- /dev/null +++ b/clang-tools-extra/docs/clang-tidy/checks/readability-redundant-declaration.rst @@ -0,0 +1,27 @@ +.. title:: clang-tidy - readability-redundant-declaration + +readability-redundant-declaration +================================= + +Finds redundant variable and function declarations. + +.. code-block:: c++ + + extern int X; + extern int X; + +becomes + +.. code-block:: c++ + + extern int X; + +Such redundant declarations can be removed without changing program behaviour. +They can for instance be unintentional left overs from previous refactorings +when code has been moved around. Having redundant declarations could in worst +case mean that there are typos in the code that cause bugs. + +Normally the code can be automatically fixed, clang-tidy can remove the second +declaration. However there are 2 cases when you need to fix the code manually: + * When the declarations are in different header files. + * When multiple variables are declared together. diff --git a/clang-tools-extra/test/clang-tidy/readability-redundant-declaration.cpp b/clang-tools-extra/test/clang-tidy/readability-redundant-declaration.cpp new file mode 100644 index 0000000..7c58596 --- /dev/null +++ b/clang-tools-extra/test/clang-tidy/readability-redundant-declaration.cpp @@ -0,0 +1,23 @@ +// RUN: %check_clang_tidy %s readability-redundant-declaration %t + +extern int Xyz; +extern int Xyz; +// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: redundant 'Xyz' declaration [readability-redundant-declaration] +// CHECK-FIXES: {{^}}{{$}} +int Xyz = 123; + +extern int A; +extern int A, B; +// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: redundant 'A' declaration +// CHECK-FIXES: {{^}}extern int A, B;{{$}} + +extern int Buf[10]; +extern int Buf[10]; +// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: redundant 'Buf' declaration +// CHECK-FIXES: {{^}}{{$}} + +static int f(); +static int f(); +// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: redundant 'f' declaration +// CHECK-FIXES: {{^}}{{$}} +static int f() {} -- 2.7.4