[c++2a] P0683R1: Permit default member initializers for bit-fields.

This would be trivial, except that our in-memory and serialized representations
for FieldDecls assumed that this can't happen.

llvm-svn: 311867

3 files changed, 48 insertions, 1 deletions

diff --git a/clang/test/PCH/cxx2a-bitfield-init.cpp b/clang/test/PCH/cxx2a-bitfield-init.cpp
new file mode 100644
index 00000000000..344f3cb9129
--- /dev/null
+++ b/clang/test/PCH/cxx2a-bitfield-init.cpp
@@ -0,0 +1,25 @@
+// RUN: %clang_cc1 -std=c++2a -include %s -verify %s
+// RUN: %clang_cc1 -std=c++2a -emit-pch %s -o %t
+// RUN: %clang_cc1 -std=c++2a -include-pch %t -verify %s -DPCH
+
+#ifndef HEADER
+#define HEADER
+
+struct S {
+  unsigned int n : 5 = 49; // expected-warning {{changes value}}
+};
+
+int a;
+template<bool B> struct T {
+  int m : B ? 8 : a = 42;
+};
+
+#else
+
+// expected-error@-5 {{constant expression}} expected-note@-5 {{cannot modify}}
+
+static_assert(S().n == 17);
+static_assert(T<true>().m == 0);
+int q = T<false>().m; // expected-note {{instantiation of}}
+
+#endif
diff --git a/clang/test/Parser/cxx2a-bitfield-init.cpp b/clang/test/Parser/cxx2a-bitfield-init.cpp
new file mode 100644
index 00000000000..83f1575c96b
--- /dev/null
+++ b/clang/test/Parser/cxx2a-bitfield-init.cpp
@@ -0,0 +1,22 @@
+// RUN: %clang_cc1 -std=c++2a -verify %s
+
+namespace std_example {
+  int a;
+  const int b = 0; // expected-note {{here}}
+  struct S {
+    int x1 : 8 = 42;
+    int x2 : 8 { 42 };
+    int y1 : true ? 8 : a = 42;
+    int y3 : (true ? 8 : b) = 42;
+    int z : 1 || new int { 1 };
+  };
+  static_assert(S{}.x1 == 42);
+  static_assert(S{}.x2 == 42);
+  static_assert(S{}.y1 == 0);
+  static_assert(S{}.y3 == 42);
+  static_assert(S{}.z == 0);
+
+  struct T {
+    int y2 : true ? 8 : b = 42; // expected-error {{cannot assign to variable 'b'}}
+  };
+}
diff --git a/clang/test/SemaCXX/member-init.cpp b/clang/test/SemaCXX/member-init.cpp
index c296baa5bce..82750878e58 100644
--- a/clang/test/SemaCXX/member-init.cpp
+++ b/clang/test/SemaCXX/member-init.cpp
@@ -1,7 +1,7 @@
 // RUN: %clang_cc1 -fsyntax-only -fcxx-exceptions -verify -std=c++11 -Wall %s
 
 struct Bitfield {
-  int n : 3 = 7; // expected-error {{bit-field member cannot have an in-class initializer}}
+  int n : 3 = 7; // expected-warning {{C++2a extension}} expected-warning {{changes value from 7 to -1}}
 };
 
 int a;