[clang-tidy] fix incorrect hint for InitListExpr in prefer-member-initializer

[HerrCai0907]

Fixes: #77684.

[llvmbot]

@llvm/pr-subscribers-clang-tidy

@llvm/pr-subscribers-clang-tools-extra

Author: Congcong Cai (HerrCai0907)

Changes

Fixes: #77684.

---

Full diff: https://github.com/llvm/llvm-project/pull/81560.diff

3 Files Affected:

• (modified) clang-tools-extra/clang-tidy/cppcoreguidelines/PreferMemberInitializerCheck.cpp (+5)
• (modified) clang-tools-extra/docs/ReleaseNotes.rst (+2-1)
• (modified) clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/prefer-member-initializer.cpp (+23)

diff --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/PreferMemberInitializerCheck.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/PreferMemberInitializerCheck.cpp
index de96c3dc4efef7..7ede900d7ba7b1 100644
--- a/clang-tools-extra/clang-tidy/cppcoreguidelines/PreferMemberInitializerCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/PreferMemberInitializerCheck.cpp
@@ -203,6 +203,7 @@ void PreferMemberInitializerCheck::check(
     SourceLocation InsertPos;
     SourceRange ReplaceRange;
     bool AddComma = false;
+    bool AddBracket = false;
     bool InvalidFix = false;
     unsigned Index = Field->getFieldIndex();
     const CXXCtorInitializer *LastInListInit = nullptr;
@@ -216,6 +217,7 @@ void PreferMemberInitializerCheck::check(
         else {
           ReplaceRange = Init->getInit()->getSourceRange();
         }
+        AddBracket = isa<InitListExpr>(Init->getInit());
         break;
       }
       if (Init->isMemberInitializer() &&
@@ -279,6 +281,9 @@ void PreferMemberInitializerCheck::check(
     if (HasInitAlready) {
       if (InsertPos.isValid())
         Diag << FixItHint::CreateInsertion(InsertPos, NewInit);
+      else if (AddBracket)
+        Diag << FixItHint::CreateReplacement(ReplaceRange,
+                                             ("{" + NewInit + "}").str());
       else
         Diag << FixItHint::CreateReplacement(ReplaceRange, NewInit);
     } else {
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index ee68c8f49b3df2..f8bc85d78315bf 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -127,7 +127,8 @@ Changes in existing checks
   <https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#c48-prefer-in-class-initializers-to-member-initializers-in-constructors-for-constant-initializers>`_,
   which was deprecated since :program:`clang-tidy` 17. This rule is now covered
   by :doc:`cppcoreguidelines-use-default-member-init
-  <clang-tidy/checks/cppcoreguidelines/use-default-member-init>`.
+  <clang-tidy/checks/cppcoreguidelines/use-default-member-init>` and fixes
+  incorrect hints when using list-initialization.
 
 - Improved :doc:`google-build-namespaces
   <clang-tidy/checks/google/build-namespaces>` check by replacing the local
diff --git a/clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/prefer-member-initializer.cpp b/clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/prefer-member-initializer.cpp
index 8086caa2aa6f2c..63b4919608ff18 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/prefer-member-initializer.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/prefer-member-initializer.cpp
@@ -616,3 +616,26 @@ class Foo {
 #undef INVALID_HANDLE_VALUE
 #undef RGB
 }
+
+namespace GH77684 {
+struct S1 {
+// CHECK-MESSAGES: :[[@LINE+1]]:16: warning: 'M' should be initialized in a member initializer of the constructor [cppcoreguidelines-prefer-member-initializer]
+  S1() : M{} { M = 0; }
+// CHECK-FIXES: {{ S1.+M\{0\} }}
+  int M;
+};
+struct S2 {
+// CHECK-MESSAGES: :[[@LINE+1]]:17: warning: 'M' should be initialized in a member initializer of the constructor [cppcoreguidelines-prefer-member-initializer]
+  S2() : M{2} { M = 1; }
+// CHECK-FIXES: {{ S2.+M\{1\} }}
+  int M;
+};
+struct T { int a; int b; int c; };
+T v;
+struct S3 {
+// CHECK-MESSAGES: :[[@LINE+1]]:21: warning: 'M' should be initialized in a member initializer of the constructor [cppcoreguidelines-prefer-member-initializer]
+  S3() : M{1,2,3} { M = v; }
+// CHECK-FIXES: {{ S3.+M\{v\} }}
+  T M;
+};
+}

[5chmidti]

Just two nits.

[5chmidti]

FYI: I have found a false-negative that is unrelated to this pr and issue, but my fix builds upon your pr. I filed an issue for it here #81613 and will post a pr once yours is merged, I don't want to make a stack just for that fix. And adding it to this pr would fix two things in one pr.

[PiotrZSL]

LGTM