[c++1z] Implement nested-namespace-definitions.

This allows 'namespace A::B { ... }' as a shorthand for 'namespace A {
namespace B { ... } }'. We already supported this correctly for error recovery;
promote that support to a full implementation.

This is not the right implementation: we do not maintain source fidelity
because we desugar the nested namespace definition in the parser. This is
tricky to avoid, since the definition genuinely does inject one named
entity per level in the namespace name.

llvm-svn: 221574

1 files changed, 38 insertions, 0 deletions

diff --git a/clang/test/Parser/cxx1z-nested-namespace-definition.cpp b/clang/test/Parser/cxx1z-nested-namespace-definition.cpp
new file mode 100644
index 0000000..96f34c5
--- /dev/null
+++ b/clang/test/Parser/cxx1z-nested-namespace-definition.cpp
@@ -0,0 +1,38 @@
+// RUN: cp %s %t
+// RUN: %clang_cc1 -fsyntax-only -verify %s
+// RUN: not %clang_cc1 -x c++ -fixit %t -Werror -DFIXIT
+// RUN: %clang_cc1 -x c++ %t -DFIXIT
+// RUN: %clang_cc1 -fsyntax-only -verify %s -std=c++1z -Wc++14-compat
+
+namespace foo1::foo2::foo3 {
+#if __cplusplus <= 201400L
+// expected-warning@-2 {{nested namespace definition is a C++1z extension; define each namespace separately}}
+#else
+// expected-warning@-4 {{nested namespace definition is incompatible with C++ standards before C++1z}}
+#endif
+  int foo(int x) { return x; }
+}
+
+#ifndef FIXIT
+inline namespace goo::bar { // expected-error {{nested namespace definition cannot be 'inline'}} expected-warning 0-1{{C++11 feature}}
+  int n;
+}
+
+int m = goo::bar::n;
+#endif
+
+int foo(int x) {
+  return foo1::foo2::foo3::foo(x);
+}
+
+namespace bar1 {
+  namespace bar2 {
+    namespace bar3 {
+      int bar(int x) { return x; }
+    }
+  }
+}
+
+int bar(int x) {
+  return bar1::bar2::bar3::bar(x);
+}