Delete implicit members whose definition does not compile (#563)

Author: lucic71

cpp2rust/converter/converter_lib.cpp

@@ -678,7 +678,10 @@ bool HasCallableCopyConstructor(const clang::RecordDecl *decl) {
              ctor->getDefinition();
     });
   }
-  if (cxx->defaultedCopyConstructorIsDeleted()) {
+  if (cxx->defaultedCopyConstructorIsDeleted() ||
+      std::ranges::any_of(cxx->ctors(), [](const auto *ctor) {
+        return ctor->isCopyConstructor() && ctor->isDeleted();
+      })) {
     return false;
   }
   auto &ctx = cxx->getASTContext();
@@ -1607,27 +1610,48 @@ void DefineImplicitMembers(clang::Sema &sema, clang::CXXRecordDecl *decl) {
   tu_scope.setEntity(sema.Context.getTranslationUnitDecl());
   auto *saved_tu_scope = std::exchange(sema.TUScope, &tu_scope);
   sema.ForceDeclarationOfImplicitMembers(decl);
+  auto define = [&](clang::FunctionDecl *fn, auto &&definer) {
+    RuleDecls::Trial trial(sema);
+    clang::DiagnosticErrorTrap errors(sema.getDiagnostics());
+    {
+      clang::Sema::GlobalEagerInstantiationScope instantiations(
+          sema, /*Enabled=*/true, /*AtEndOfTU=*/false);
+      definer();
+      instantiations.perform();
+    }
+    if (trial.failed() || errors.hasErrorOccurred()) {
+      fn->setDeletedAsWritten(true);
+    }
+  };
   for (auto ctor : decl->ctors()) {
     if (ctor->isCopyConstructor() && ctor->isImplicit() &&
         !ctor->doesThisDeclarationHaveABody() && !ctor->isDeleted()) {
-      sema.DefineImplicitCopyConstructor(decl->getLocation(), ctor);
+      define(ctor, [&] {
+        sema.DefineImplicitCopyConstructor(decl->getLocation(), ctor);
+      });
     }
     if (ctor->isMoveConstructor() && !ctor->isUserProvided() &&
         !ctor->doesThisDeclarationHaveABody() && !ctor->isDeleted() &&
         !HasDefaultedCopyConstructor(decl)) {
-      sema.DefineImplicitMoveConstructor(decl->getLocation(), ctor);
+      define(ctor, [&] {
+        sema.DefineImplicitMoveConstructor(decl->getLocation(), ctor);
+      });
     }
   }
   for (auto *method : decl->methods()) {
     if (method->isMoveAssignmentOperator() && !method->isUserProvided() &&
         !method->doesThisDeclarationHaveABody() && !method->isDeleted() &&
         !HasDefaultedCopyAssignment(decl)) {
-      sema.DefineImplicitMoveAssignment(decl->getLocation(), method);
+      define(method, [&] {
+        sema.DefineImplicitMoveAssignment(decl->getLocation(), method);
+      });
     }
     if (method->isCopyAssignmentOperator() && !method->isUserProvided() &&
         !method->doesThisDeclarationHaveABody() && !method->isDeleted() &&
         NeedsDefaultedCopyAssignment(decl)) {
-      sema.DefineImplicitCopyAssignment(decl->getLocation(), method);
+      define(method, [&] {
+        sema.DefineImplicitCopyAssignment(decl->getLocation(), method);
+      });
     }
   }
   auto define_defaulted_comparison = [&](clang::FunctionDecl *fn) {
@@ -1640,7 +1664,9 @@ void DefineImplicitMembers(clang::Sema &sema, clang::CXXRecordDecl *decl) {
 #else
     auto kind = sema.getDefaultedComparisonKind(fn);
 #endif
-    sema.DefineDefaultedComparison(decl->getLocation(), fn, kind);
+    define(fn, [&] {
+      sema.DefineDefaultedComparison(decl->getLocation(), fn, kind);
+    });
   };
   for (auto *method : decl->methods()) {
     define_defaulted_comparison(method);

tests/unit/copy_move_deleted.cpp

@@ -1,5 +1,6 @@
 #include <cassert>
 #include <utility>
+#include <vector>
 
 struct NoCopy {
   int v;
@@ -43,6 +44,10 @@ struct Container {
   int tag;
 };
 
+struct VecHolder {
+  std::vector<NoCopy> items;
+};
+
 static void bump(NoCopy *p) { p->v++; }
 static void bump_ref(Immovable &r) { r.v++; }
 
@@ -71,5 +76,9 @@ int main() {
   Container c{NoCopy(6), 7};
   Container d(std::move(c));
   assert(d.inner.v == 6 && d.tag == 7 && c.inner.v == 0);
+
+  VecHolder h;
+  VecHolder h2(std::move(h));
+  assert(h2.items.size() == 0);
   return 0;
 }

tests/unit/out/refcount/copy_move_deleted.rs

@@ -80,6 +80,20 @@ impl Container {
         }
     }
 }
+#[derive(Record, ByteRepr, FnPtrArg, MoveCtor, Default)]
+#[byte_size(24)]
+pub struct VecHolder {
+    #[offset(0)]
+    #[byte_size(24)]
+    pub items: Vec<NoCopy>,
+}
+impl VecHolder {
+    pub fn move_from(_a0: Ptr<VecHolder>) -> Self {
+        Self {
+            items: field!(_a0, items).with_mut(std::mem::take),
+        }
+    }
+}
 pub fn bump_0(mut p: Ptr<NoCopy>) {
     field!(p, v).with_mut(|__v| __v.postfix_inc());
 }
@@ -115,6 +129,9 @@ fn main_0() -> i32 {
     }));
     let mut d: Container = Container::move_from({ c.as_pointer() });
     assert!(((d.inner.v == 6) && (d.tag == 7)) && ({ (*c.borrow()).inner.v } == 0));
+    let h: Value<VecHolder> = Rc::new(RefCell::new(<VecHolder>::default()));
+    let mut h2: VecHolder = VecHolder::move_from({ h.as_pointer() });
+    assert!((h2.items.len() == 0_usize));
     return 0;
 }
 pub trait ContainerImpl {

tests/unit/out/unsafe/copy_move_deleted.rs

@@ -92,6 +92,19 @@ impl Container {
         return &mut (*(self as *mut Container));
     }
 }
+#[repr(C)]
+#[derive(FnPtrArg, MoveCtorUnsafe, Default)]
+pub struct VecHolder {
+    pub items: Vec<NoCopy>,
+}
+impl VecHolder {
+    pub unsafe fn move_from(_a0: *mut VecHolder) -> Self {
+        let mut this = Self {
+            items: std::mem::take(&mut (*_a0).items),
+        };
+        this
+    }
+}
 pub unsafe fn bump_0(mut p: *mut NoCopy) {
     (*p).v.postfix_inc();
 }
@@ -129,6 +142,9 @@ unsafe fn main_0() -> i32 {
     };
     let mut d: Container = Container::move_from({ &mut c });
     assert!((((d.inner.v) == (6)) && ((d.tag) == (7))) && ((c.inner.v) == (0)));
+    let mut h: VecHolder = <VecHolder>::default();
+    let mut h2: VecHolder = VecHolder::move_from({ &mut h });
+    assert!(((h2.items.len()) == (0_usize)));
     return 0;
 }
 pub unsafe fn __cpp2rust_init_globals() {}