From 883ebacd7885be5299e171da2e46e278c13bf671 Mon Sep 17 00:00:00 2001
From: Malcolm Parsons <malcolm.parsons@gmail.com>
Date: Tue, 1 Nov 2016 21:26:53 +0000
Subject: [PATCH] [clang-tidy] Handle bitfields in
 cppcoreguidelines-pro-type-member-init

Summary:
Unnamed bitfields cannot be initialized.
Bitfields cannot be in-class initialized.

Reviewers: alexfh, hokein, aaron.ballman

Subscribers: Prazek, nemanjai, cfe-commits

Differential Revision: https://reviews.llvm.org/D26119

llvm-svn: 285752
---
 .../ProTypeMemberInitCheck.cpp                  |  6 ++++--
 .../cppcoreguidelines-pro-type-member-init.cpp  | 17 +++++++++++++++++
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeMemberInitCheck.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeMemberInitCheck.cpp
index 272e2dad1bef..a5c26482e4d6 100644
--- a/clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeMemberInitCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeMemberInitCheck.cpp
@@ -358,7 +358,7 @@ void ProTypeMemberInitCheck::checkMissingMemberInitializer(
     if (!F->hasInClassInitializer() &&
         utils::type_traits::isTriviallyDefaultConstructible(F->getType(),
                                                             Context) &&
-        !isEmpty(Context, F->getType()))
+        !isEmpty(Context, F->getType()) && !F->isUnnamedBitfield())
       FieldsToInit.insert(F);
   });
   if (FieldsToInit.empty())
@@ -407,7 +407,9 @@ void ProTypeMemberInitCheck::checkMissingMemberInitializer(
   SmallPtrSet<const FieldDecl *, 16> FieldsToFix;
   forEachField(ClassDecl, FieldsToInit, true, [&](const FieldDecl *F) {
     // Don't suggest fixes for enums because we don't know a good default.
-    if (!F->getType()->isEnumeralType())
+    // Don't suggest fixes for bitfields because in-class initialization is not
+    // possible.
+    if (!F->getType()->isEnumeralType() && !F->isBitField())
       FieldsToFix.insert(F);
   });
   if (FieldsToFix.empty())
diff --git a/clang-tools-extra/test/clang-tidy/cppcoreguidelines-pro-type-member-init.cpp b/clang-tools-extra/test/clang-tidy/cppcoreguidelines-pro-type-member-init.cpp
index c287c5c4eace..08481a8918c6 100644
--- a/clang-tools-extra/test/clang-tidy/cppcoreguidelines-pro-type-member-init.cpp
+++ b/clang-tools-extra/test/clang-tidy/cppcoreguidelines-pro-type-member-init.cpp
@@ -456,3 +456,20 @@ template <typename T> class NoCrash {
     template <typename U> B(U u) {}
   };
 };
+
+struct PositiveBitfieldMember {
+  PositiveBitfieldMember() {}
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: constructor does not initialize these fields: F
+  unsigned F : 5;
+};
+
+struct NegativeUnnamedBitfieldMember {
+  NegativeUnnamedBitfieldMember() {}
+  unsigned : 5;
+};
+
+struct NegativeInitializedBitfieldMembers {
+  NegativeInitializedBitfieldMembers() : F(3) { G = 2; }
+  unsigned F : 5;
+  unsigned G : 5;
+};