Author: hokein Date: Thu Oct 18 02:13:34 2018 New Revision: 344733 URL: http://llvm.org/viewvc/llvm-project?rev=344733&view=rev Log: [clang-tidy] Ignore a case where the fix of make_unique check introduces side effect.
Summary: Previously, ptr.reset(new char[5]) will be replaced with `p = make_unique<char[]>(5)`, the fix has side effect -- doing default initialization, it may cause performace regression (we are bitten by this rececntly) The check should be conservative for these cases. Reviewers: alexfh Subscribers: xazax.hun, cfe-commits Differential Revision: https://reviews.llvm.org/D53377 Modified: clang-tools-extra/trunk/clang-tidy/modernize/MakeSmartPtrCheck.cpp clang-tools-extra/trunk/test/clang-tidy/modernize-make-unique.cpp Modified: clang-tools-extra/trunk/clang-tidy/modernize/MakeSmartPtrCheck.cpp URL: http://llvm.org/viewvc/llvm-project/clang-tools-extra/trunk/clang-tidy/modernize/MakeSmartPtrCheck.cpp?rev=344733&r1=344732&r2=344733&view=diff ============================================================================== --- clang-tools-extra/trunk/clang-tidy/modernize/MakeSmartPtrCheck.cpp (original) +++ clang-tools-extra/trunk/clang-tidy/modernize/MakeSmartPtrCheck.cpp Thu Oct 18 02:13:34 2018 @@ -121,6 +121,15 @@ void MakeSmartPtrCheck::check(const Matc if (New->getNumPlacementArgs() != 0) return; + // Be conservative for cases where we construct an array without any + // initalization. + // For example, + // P.reset(new int[5]) // check fix: P = make_unique<int []>(5) + // + // The fix of the check has side effect, it introduces default initialization + // which maybe unexpected and cause performance regression. + if (New->isArray() && !New->hasInitializer()) + return; if (Construct) checkConstruct(SM, Result.Context, Construct, Type, New); else if (Reset) Modified: clang-tools-extra/trunk/test/clang-tidy/modernize-make-unique.cpp URL: http://llvm.org/viewvc/llvm-project/clang-tools-extra/trunk/test/clang-tidy/modernize-make-unique.cpp?rev=344733&r1=344732&r2=344733&view=diff ============================================================================== --- clang-tools-extra/trunk/test/clang-tidy/modernize-make-unique.cpp (original) +++ clang-tools-extra/trunk/test/clang-tidy/modernize-make-unique.cpp Thu Oct 18 02:13:34 2018 @@ -403,18 +403,15 @@ void initialization(int T, Base b) { // CHECK-FIXES: FFs = std::make_unique<Foo[]>(Num2); std::unique_ptr<int[]> FI; - FI.reset(new int[5]); - // CHECK-MESSAGES: :[[@LINE-1]]:6: warning: - // CHECK-FIXES: FI = std::make_unique<int[]>(5); - FI.reset(new int[5]()); + FI.reset(new int[5]()); // default initialization. // CHECK-MESSAGES: :[[@LINE-1]]:6: warning: // CHECK-FIXES: FI = std::make_unique<int[]>(5); + + // The check doesn't give warnings and fixes for cases where the original new + // expresion doesn't do any initialization. + FI.reset(new int[5]); FI.reset(new int[Num]); - // CHECK-MESSAGES: :[[@LINE-1]]:6: warning: - // CHECK-FIXES: FI = std::make_unique<int[]>(Num); FI.reset(new int[Num2]); - // CHECK-MESSAGES: :[[@LINE-1]]:6: warning: - // CHECK-FIXES: FI = std::make_unique<int[]>(Num2); } void aliases() { _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
