Move checks for creation of objects of abstract class type from the various

constructs that can do so into the initialization code. This fixes a number
of different cases in which we used to fail to check for abstract types.

Thanks to Tim Shen for inspiring the weird code that uncovered this!

llvm-svn: 289753

2 files changed, 120 insertions, 0 deletions

diff --git a/clang/test/CXX/class.derived/class.abstract/p2.cpp b/clang/test/CXX/class.derived/class.abstract/p2.cpp
new file mode 100644
index 00000000000..713a5269f14
--- /dev/null
+++ b/clang/test/CXX/class.derived/class.abstract/p2.cpp
@@ -0,0 +1,23 @@
+// RUN: %clang_cc1 -std=c++1z -verify %s
+
+// no objects of an abstract class can be created except as subobjects of a
+// class derived from it
+
+struct A {
+  A() {}
+  A(int) : A() {} // ok
+
+  virtual void f() = 0; // expected-note 1+{{unimplemented}}
+};
+
+void f(A &&a);
+
+void g() {
+  f({}); // expected-error {{abstract class}}
+  f({0}); // expected-error {{abstract class}}
+  f(0); // expected-error {{abstract class}}
+}
+
+struct B : A {
+  B() : A() {} // ok
+};
diff --git a/clang/test/CXX/class.derived/class.abstract/p3.cpp b/clang/test/CXX/class.derived/class.abstract/p3.cpp
new file mode 100644
index 00000000000..ad5b8747883
--- /dev/null
+++ b/clang/test/CXX/class.derived/class.abstract/p3.cpp
@@ -0,0 +1,97 @@
+// RUN: %clang_cc1 -std=c++1z -verify %s
+
+struct A {
+  A() {}
+  A(int) : A() {} // ok
+
+  virtual void f() = 0; // expected-note 1+{{unimplemented}}
+};
+
+template<typename> struct SecretlyAbstract {
+  SecretlyAbstract();
+  SecretlyAbstract(int);
+  virtual void f() = 0; // expected-note 1+{{unimplemented}}
+};
+using B = SecretlyAbstract<int>;
+using C = SecretlyAbstract<float>;
+using D = SecretlyAbstract<char>[1];
+
+B b; // expected-error {{abstract class}}
+D d; // expected-error {{abstract class}}
+
+template<int> struct N;
+
+// Note: C is not instantiated anywhere in this file, so we never discover that
+// it is in fact abstract. The C++ standard suggests that we need to
+// instantiate in all cases where abstractness could affect the validity of a
+// program, but that breaks a *lot* of code, so we don't do that.
+//
+// FIXME: Once DR1640 is resolved, remove the check on forming an abstract
+// array type entirely. The only restriction we need is that you can't create
+// an object of abstract (most-derived) type.
+
+
+// An abstract class shall not be used
+
+//  - as a parameter type
+void f(A&);
+void f(A); // expected-error {{abstract class}}
+void f(A[1]); // expected-error {{abstract class}}
+void f(B); // expected-error {{abstract class}}
+void f(B[1]); // expected-error {{abstract class}}
+void f(C);
+void f(C[1]);
+void f(D); // expected-error {{abstract class}}
+void f(D[1]); // expected-error {{abstract class}}
+
+//  - as a function return type
+A &f(N<0>);
+A *f(N<1>);
+A f(N<2>); // expected-error {{abstract class}}
+A (&f(N<3>))[2]; // expected-error {{abstract class}}
+B f(N<4>); // expected-error {{abstract class}}
+B (&f(N<5>))[2]; // expected-error {{abstract class}}
+C f(N<6>);
+C (&f(N<7>))[2];
+
+//  - as the type of an explicit conversion
+void g(A&&);
+void h() {
+  A(); // expected-error {{abstract class}}
+  A(0); // expected-error {{abstract class}}
+  A{}; // expected-error {{abstract class}}
+  A{0}; // expected-error {{abstract class}}
+  (A)(0); // expected-error {{abstract class}}
+  (A){}; // expected-error {{abstract class}}
+  (A){0}; // expected-error {{abstract class}}
+
+  D(); // expected-error {{array type}}
+  D{}; // expected-error {{abstract class}}
+  D{0}; // expected-error {{abstract class}}
+  (D){}; // expected-error {{abstract class}}
+  (D){0}; // expected-error {{abstract class}}
+}
+
+template<typename T> void t(T); // expected-note 2{{abstract class}}
+void i(A &a, B &b, C &c, D &d) {
+  // FIXME: These should be handled consistently. We currently reject the first
+  // two early because we (probably incorrectly, depending on dr1640) take
+  // abstractness into account in forming implicit conversion sequences.
+  t(a); // expected-error {{no matching function}}
+  t(b); // expected-error {{no matching function}}
+  t(c); // expected-error {{allocating an object of abstract class type}}
+  t(d); // ok, decays to pointer
+}
+
+struct E : A {
+  E() : A() {} // ok
+  E(int n) : A( A(n) ) {} // expected-error {{abstract class}}
+};
+
+namespace std {
+  template<typename T> struct initializer_list {
+    const T *begin, *end;
+    initializer_list();
+  };
+}
+std::initializer_list<A> ila = {1, 2, 3, 4}; // expected-error {{abstract class}}