[clang-tools-extra] [clang-tidy] The first PR our of many PRs for the "Initialized Class Members" check. (PR #65189)

[via cfe-commits]

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+//===--- CppInitClassMembersCheck.cpp - clang-tidy ------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <string>
+
+#include "CppInitClassMembersCheck.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/Decl.h"
+#include "clang/AST/Type.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/ASTMatchers/ASTMatchers.h"
+#include "clang/ASTMatchers/ASTMatchersMacros.h"
+#include "clang/Basic/Diagnostic.h"
+#include "clang/Basic/LLVM.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/Support/raw_ostream.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::google {
+
+namespace {
+
+// Matches records that have a default constructor.
+AST_MATCHER(CXXRecordDecl, hasDefaultConstructor) {
+  return Node.hasDefaultConstructor();
+}
+
+// Returns the names of `Fields` in a comma separated string.
+std::string
+toCommaSeparatedString(const SmallVector<const FieldDecl *, 16> &Fields) {
+  std::string Buffer;
+  llvm::raw_string_ostream OS(Buffer);
+  llvm::interleave(
+      Fields, OS, [&OS](const FieldDecl *Decl) { OS << Decl->getName(); },
+      ", ");
+  return Buffer;
+}
+
+// Returns `true` for field types that should be reported (if additional
+// conditions are also met). For example, returns `true` for `int` because an
+// uninitialized `int` field can contain uninitialized values.
+bool shouldReportThisFieldType(QualType Ty) {
+  if (Ty.isNull())
+    return false;
+
+  // FIXME: For now, this checker focuses on several allowlisted types. We will
+  // expand coverage in future.
+  return Ty->isIntegerType() || Ty->isBooleanType();
+}
+
+} // anonymous namespace
+
+void CppInitClassMembersCheck::checkMissingMemberInitializer(
+    ASTContext &Context, const CXXRecordDecl &ClassDecl,
+    const CXXConstructorDecl *Ctor) {
+  SmallVector<const FieldDecl *, 16> FieldsToReport;
+
+  for (const FieldDecl *F : ClassDecl.fields()) {
+    if (shouldReportThisFieldType(F->getType()) && !F->hasInClassInitializer())
+      FieldsToReport.push_back(F);
+  }
+
+  if (FieldsToReport.empty())
+    return;
+
+  DiagnosticBuilder Diag =
+      diag(Ctor ? Ctor->getBeginLoc() : ClassDecl.getLocation(),
+           "%select{these fields should be initialized|constructor should "
+           "initialize these fields}0: %1")
+      << (Ctor != nullptr) << toCommaSeparatedString(FieldsToReport);
+
+  // FIXME: generate fixes.
+}
+
+void CppInitClassMembersCheck::registerMatchers(MatchFinder *Finder) {
+  Finder->addMatcher(cxxConstructorDecl(isDefinition(), isDefaultConstructor(),
----------------
adriannistor wrote:

I added this as a TODO in a0d227088b9d099b23ed68af80714e2f96a7a2a8 (file `cpp-init-class-members.cpp`).

As discussed in the [broader discussion below](https://github.com/llvm/llvm-project/pull/65189#issuecomment-1709185690), this current PR is just the first of many PRs.

I am now tracking this issue (the above TODO) and I am also tracking it in an internal tracker. As I mention in an [above comment](https://github.com/llvm/llvm-project/pull/65189#discussion_r1318928101), if you would prefer that I use the [LLVM issue tracker](https://github.com/llvm/llvm-project/issues/) to track these feature requests, I would be very glad to do that (just let me know!). I am not doing it for now (except if you give me feedback that I should do it) because I am worried that I will flood the LLVM tracker with issues for a checker that is currently under development (and has many features upcoming).  In short, I am glad to wither use the LLVM tracker or not use it, just let me know what you would prefer! Thanks! 


https://github.com/llvm/llvm-project/pull/65189