[clang-tools-extra] [clang-tidy] ignore uninitialized std::array in member init (PR #98134)

[via cfe-commits]

https://github.com/dsiroky updated https://github.com/llvm/llvm-project/pull/98134

>From e70c56ecb8bd899f6ff93c55303fca1fa217a336 Mon Sep 17 00:00:00 2001
From: David Siroky <david at siroky.cz>
Date: Tue, 9 Jul 2024 10:50:00 +0200
Subject: [PATCH] [clang-tidy] ignore uninitialized std::array in member init

cppcoreguidelines-pro-type-member-init check has an option IgnoreArrays
for ignoring uninitialized C arrays. This patch adds support for C++
std::array as well.
---
 .../cppcoreguidelines/ProTypeMemberInitCheck.cpp    | 13 ++++++++++++-
 clang-tools-extra/docs/ReleaseNotes.rst             |  4 ++++
 .../cppcoreguidelines/pro-type-member-init.rst      |  7 ++++---
 .../pro-type-member-init.ignorearrays.cpp           |  7 +++++++
 4 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeMemberInitCheck.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeMemberInitCheck.cpp
index 54b8a72c865af..a8e1dfa19d657 100644
--- a/clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeMemberInitCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeMemberInitCheck.cpp
@@ -431,6 +431,16 @@ static StringRef getInitializer(QualType QT, bool UseAssignment) {
   }
 }
 
+static bool isStdArray(QualType QT) {
+  const auto *RT = QT->getAs<RecordType>();
+  if (!RT)
+    return false;
+  const auto *RD = RT->getDecl();
+  if (!RD || !RD->getIdentifier())
+    return false;
+  return RD->getName() == "array" && RD->isInStdNamespace();
+}
+
 static void
 computeFieldsToInit(const ASTContext &Context, const RecordDecl &Record,
                     bool IgnoreArrays,
@@ -439,7 +449,8 @@ computeFieldsToInit(const ASTContext &Context, const RecordDecl &Record,
   forEachFieldWithFilter(
       Record, Record.fields(), AnyMemberHasInitPerUnion,
       [&](const FieldDecl *F) {
-        if (IgnoreArrays && F->getType()->isArrayType())
+        if (IgnoreArrays &&
+            (F->getType()->isArrayType() || isStdArray(F->getType())))
           return;
         if (F->hasInClassInitializer() && F->getParent()->isUnion()) {
           AnyMemberHasInitPerUnion = true;
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index 0ad69f5fdc5aa..d22032e691410 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -158,6 +158,10 @@ Changes in existing checks
   the invalidating function in the warning message when a custom invalidation
   function is used (via the `InvalidationFunctions` option).
 
+- Improved :doc:`cppcoreguidelines-pro-type-member-init
+  <clang-tidy/checks/cppcoreguidelines/pro-type-member-init>` check by treating
+  ``std::array`` the same as built-in arrays when ``IgnoreArrays`` is enabled.
+
 - Improved :doc:`cppcoreguidelines-pro-type-vararg
   <clang-tidy/checks/cppcoreguidelines/pro-type-vararg>` check by no longer
   warning on builtins with custom type checking (e.g., type-generic builtins
diff --git a/clang-tools-extra/docs/clang-tidy/checks/cppcoreguidelines/pro-type-member-init.rst b/clang-tools-extra/docs/clang-tidy/checks/cppcoreguidelines/pro-type-member-init.rst
index b86083f82300d..9439638e699cd 100644
--- a/clang-tools-extra/docs/clang-tidy/checks/cppcoreguidelines/pro-type-member-init.rst
+++ b/clang-tools-extra/docs/clang-tidy/checks/cppcoreguidelines/pro-type-member-init.rst
@@ -29,9 +29,10 @@ Options
 
 .. option:: IgnoreArrays
 
-   If set to `true`, the check will not warn about array members that are not
-   zero-initialized during construction. For performance critical code, it may
-   be important to not initialize fixed-size array members. Default is `false`.
+   If set to `true`, the check will not warn about array members (including
+   ``std::array``) that are not zero-initialized during construction. For
+   performance critical code, it may be important to not initialize fixed-size
+   array members. Default is `false`.
 
 .. option:: UseAssignment
 
diff --git a/clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/pro-type-member-init.ignorearrays.cpp b/clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/pro-type-member-init.ignorearrays.cpp
index e4cfe679cfce9..30db741b3f176 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/pro-type-member-init.ignorearrays.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/pro-type-member-init.ignorearrays.cpp
@@ -27,6 +27,13 @@ void test_local_std_array() {
   std::array<int, 4> a;
 }
 
+struct HasStdArrayMember {
+  // CHECK-MESSAGES: warning: constructor does not initialize these fields: Number
+  HasStdArrayMember() {}
+  std::array<int, 4> StdArray;
+  int Number;
+};
+
 struct OnlyArray {
   int a[4];
 };