[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

llvm-svn: 344733

1 files changed, 5 insertions, 8 deletions

diff --git a/clang-tools-extra/test/clang-tidy/modernize-make-unique.cpp b/clang-tools-extra/test/clang-tidy/modernize-make-unique.cpp
index d2a73f3f311..aeeb6dbd809 100644
--- a/clang-tools-extra/test/clang-tidy/modernize-make-unique.cpp
+++ b/clang-tools-extra/test/clang-tidy/modernize-make-unique.cpp
@@ -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() {