[clang] [Clang] Implement the core language parts of P2786 - Trivial relocation (PR #127636)

[via cfe-commits]

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@@ -7258,6 +7261,221 @@ void Sema::CheckCompletedCXXClass(Scope *S, CXXRecordDecl *Record) {
   }
 }
 
+static bool hasSuitableConstructorForReplaceability(CXXRecordDecl *D,
+                                                    bool Implicit) {
+  assert(D->hasDefinition() && !D->isInvalidDecl());
+
+  bool HasDeletedMoveConstructor = false;
+  bool HasDeletedCopyConstructor = false;
+  bool HasMoveConstructor = D->needsImplicitMoveConstructor();
+  bool HasDefaultedMoveConstructor = D->needsImplicitMoveConstructor();
+  bool HasDefaultedCopyConstructor = D->needsImplicitMoveConstructor();
+
+  for (const Decl *D : D->decls()) {
+    auto *MD = dyn_cast<CXXConstructorDecl>(D);
+    if (!MD || MD->isIneligibleOrNotSelected())
+      continue;
+
+    if (MD->isMoveConstructor()) {
+      HasMoveConstructor = true;
+      if (MD->isDefaulted())
+        HasDefaultedMoveConstructor = true;
+      if (MD->isDeleted())
+        HasDeletedMoveConstructor = true;
+    }
+    if (MD->isCopyConstructor()) {
+      if (MD->isDefaulted())
+        HasDefaultedCopyConstructor = true;
+      if (MD->isDeleted())
+        HasDeletedCopyConstructor = true;
+    }
+  }
+
+  if (HasMoveConstructor)
+    return !HasDeletedMoveConstructor &&
+           (Implicit ? HasDefaultedMoveConstructor : true);
+  return !HasDeletedCopyConstructor &&
+         (Implicit ? HasDefaultedCopyConstructor : true);
+  ;
+}
+
+static bool hasSuitableMoveAssignmentOperatorForReplaceability(CXXRecordDecl *D,
+                                                               bool Implicit) {
+  assert(D->hasDefinition() && !D->isInvalidDecl());
+
+  if (D->hasExplicitlyDeletedMoveAssignment())
+    return false;
+
+  bool HasDeletedMoveAssignment = false;
+  bool HasDeletedCopyAssignment = false;
+  bool HasMoveAssignment = D->needsImplicitMoveAssignment();
+  bool HasDefaultedMoveAssignment = D->needsImplicitMoveAssignment();
+  bool HasDefaultedCopyAssignment = D->needsImplicitCopyAssignment();
+
+  for (const Decl *D : D->decls()) {
+    auto *MD = dyn_cast<CXXMethodDecl>(D);
+    if (!MD || MD->isIneligibleOrNotSelected())
+      continue;
+
+    if (MD->isMoveAssignmentOperator()) {
+      HasMoveAssignment = true;
+      if (MD->isDefaulted())
+        HasDefaultedMoveAssignment = true;
+      if (MD->isDeleted())
+        HasDeletedMoveAssignment = true;
+    }
+    if (MD->isCopyAssignmentOperator()) {
+      if (MD->isDefaulted())
+        HasDefaultedCopyAssignment = true;
+      if (MD->isDeleted())
+        HasDeletedCopyAssignment = true;
+    }
+  }
+
+  if (HasMoveAssignment)
+    return !HasDeletedMoveAssignment &&
+           (Implicit ? HasDefaultedMoveAssignment : true);
+  return !HasDeletedCopyAssignment &&
+         (Implicit ? HasDefaultedCopyAssignment : true);
+}
+
+void Sema::CheckCXX2CTriviallyRelocatable(CXXRecordDecl *D) {
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Sirraide wrote:

Also, I wonder if having separate functions for e.g. `isDefaultMovable()` and `isEligibleForTrivialRelocation()` might help here.

https://github.com/llvm/llvm-project/pull/127636