DR1672, DR1813, DR1881, DR2120: Implement recent fixes to "standard

layout" rules.

The new rules say that a standard-layout struct has its first non-static
data member and all base classes at offset 0, and consider a class to
not be standard-layout if that would result in multiple subobjects of a
single type having the same address.

We track "is C++11 standard-layout class" separately from "is
standard-layout class" so that the ABIs that need this information can
still use it.

Differential Revision: https://reviews.llvm.org/D45176

5 files changed, 85 insertions, 2 deletions

diff --git a/clang/test/CXX/drs/dr14xx.cpp b/clang/test/CXX/drs/dr14xx.cpp
index 116437b1ab3..eb5ba3db448 100644
--- a/clang/test/CXX/drs/dr14xx.cpp
+++ b/clang/test/CXX/drs/dr14xx.cpp
@@ -7,6 +7,8 @@
 // expected-no-diagnostics
 #endif
 
+// dr1425: na abi
+
 namespace dr1460 { // dr1460: 3.5
 #if __cplusplus >= 201103L
   namespace DRExample {
diff --git a/clang/test/CXX/drs/dr16xx.cpp b/clang/test/CXX/drs/dr16xx.cpp
index 08ae92570ce..898672ab807 100644
--- a/clang/test/CXX/drs/dr16xx.cpp
+++ b/clang/test/CXX/drs/dr16xx.cpp
@@ -3,6 +3,11 @@
 // RUN: %clang_cc1 -std=c++14 -triple x86_64-unknown-unknown %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
 // RUN: %clang_cc1 -std=c++1z -triple x86_64-unknown-unknown %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
 
+#if __cplusplus < 201103L
+// expected-error@+1 {{variadic macro}}
+#define static_assert(...) __extension__ _Static_assert(__VA_ARGS__)
+#endif
+
 namespace dr1611 { // dr1611: dup 1658
   struct A { A(int); };
   struct B : virtual A { virtual void f() = 0; };
@@ -219,3 +224,28 @@ namespace dr1658 { // dr1658: 5
 
   // assignment case is superseded by dr2180
 }
+
+namespace dr1672 { // dr1672: 7
+  struct Empty {};
+  struct A : Empty {};
+  struct B { Empty e; };
+  struct C : A { B b; int n; };
+  struct D : A { int n; B b; };
+
+  static_assert(!__is_standard_layout(C), "");
+  static_assert(__is_standard_layout(D), "");
+
+  struct E { B b; int n; };
+  struct F { int n; B b; };
+  union G { B b; int n; };
+  union H { int n; B b; };
+
+  struct X {};
+  template<typename T> struct Y : X, A { T t; };
+
+  static_assert(!__is_standard_layout(Y<E>), "");
+  static_assert(__is_standard_layout(Y<F>), "");
+  static_assert(!__is_standard_layout(Y<G>), "");
+  static_assert(!__is_standard_layout(Y<H>), "");
+  static_assert(!__is_standard_layout(Y<X>), "");
+}
diff --git a/clang/test/CXX/drs/dr18xx.cpp b/clang/test/CXX/drs/dr18xx.cpp
index e4ec199fcae..a0f470ed4a2 100644
--- a/clang/test/CXX/drs/dr18xx.cpp
+++ b/clang/test/CXX/drs/dr18xx.cpp
@@ -4,9 +4,44 @@
 // RUN: %clang_cc1 -std=c++1z -triple x86_64-unknown-unknown %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
 
 #if __cplusplus < 201103L
-// expected-no-diagnostics
+// expected-error@+1 {{variadic macro}}
+#define static_assert(...) __extension__ _Static_assert(__VA_ARGS__)
 #endif
 
+namespace dr1813 { // dr1813: 7
+  struct B { int i; };
+  struct C : B {};
+  struct D : C {};
+  struct E : D { char : 4; };
+
+  static_assert(__is_standard_layout(B), "");
+  static_assert(__is_standard_layout(C), "");
+  static_assert(__is_standard_layout(D), "");
+  static_assert(!__is_standard_layout(E), "");
+
+  struct Q {};
+  struct S : Q {};
+  struct T : Q {};
+  struct U : S, T {};
+
+  static_assert(__is_standard_layout(Q), "");
+  static_assert(__is_standard_layout(S), "");
+  static_assert(__is_standard_layout(T), "");
+  static_assert(!__is_standard_layout(U), "");
+}
+
+namespace dr1881 { // dr1881: 7
+  struct A { int a : 4; };
+  struct B : A { int b : 3; };
+  static_assert(__is_standard_layout(A), "");
+  static_assert(!__is_standard_layout(B), "");
+
+  struct C { int : 0; };
+  struct D : C { int : 0; };
+  static_assert(__is_standard_layout(C), "");
+  static_assert(!__is_standard_layout(D), "");
+}
+
 void dr1891() { // dr1891: 4
 #if __cplusplus >= 201103L
   int n;
diff --git a/clang/test/CXX/drs/dr21xx.cpp b/clang/test/CXX/drs/dr21xx.cpp
index 78fc0bec40b..2522ff7dbde 100644
--- a/clang/test/CXX/drs/dr21xx.cpp
+++ b/clang/test/CXX/drs/dr21xx.cpp
@@ -3,6 +3,22 @@
 // RUN: %clang_cc1 -std=c++14 -triple x86_64-unknown-unknown %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
 // RUN: %clang_cc1 -std=c++1z -triple x86_64-unknown-unknown %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
 
+#if __cplusplus < 201103L
+// expected-error@+1 {{variadic macro}}
+#define static_assert(...) __extension__ _Static_assert(__VA_ARGS__)
+#endif
+
+namespace dr2120 { // dr2120: 7
+  struct A {};
+  struct B : A {};
+  struct C { A a; };
+  struct D { C c[5]; };
+  struct E : B { D d; };
+  static_assert(__is_standard_layout(B), "");
+  static_assert(__is_standard_layout(D), "");
+  static_assert(!__is_standard_layout(E), "");
+}
+
 namespace dr2180 { // dr2180: yes
   class A {
     A &operator=(const A &); // expected-note 0-2{{here}}
diff --git a/clang/test/CXX/drs/dr22xx.cpp b/clang/test/CXX/drs/dr22xx.cpp
index 55b3d782077..021707d876b 100644
--- a/clang/test/CXX/drs/dr22xx.cpp
+++ b/clang/test/CXX/drs/dr22xx.cpp
@@ -3,7 +3,7 @@
 // RUN: %clang_cc1 -std=c++14 -triple x86_64-unknown-unknown %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
 // RUN: %clang_cc1 -std=c++1z -triple x86_64-unknown-unknown %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
 
-namespace dr2229 { // dr2229: yes
+namespace dr2229 { // dr2229: 7
 struct AnonBitfieldQualifiers {
   const unsigned : 1; // expected-error {{anonymous bit-field cannot have qualifiers}}
   volatile unsigned : 1; // expected-error {{anonymous bit-field cannot have qualifiers}}