Audit __private_extern__ handling.
 - Exposed quite a few Sema issues and a CodeGen crash.

 - See FIXMEs in test case, and in SemaDecl.cpp (PR3983).

I'm skeptical that __private_extern__ should actually be a storage
class value. I think that __private_extern__ basically amounts to
  extern A __attribute__((visibility("hidden")))
and would be better off handled (a) as that, or (b) with an extra bit
in the VarDecl.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@69020 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/Sema/private-extern.c b/test/Sema/private-extern.c
new file mode 100644
index 0000000..f787b7d
--- /dev/null
+++ b/test/Sema/private-extern.c
@@ -0,0 +1,89 @@
+// RUN: clang-cc -verify -fsyntax-only %s
+
+static int g0; // expected-note{{previous definition}}
+int g0; // expected-error{{non-static declaration of 'g0' follows static declaration}}
+
+static int g1;
+extern int g1;
+
+static int g2; 
+__private_extern__ int g2;
+
+int g3; // expected-note{{previous definition}}
+static int g3; // expected-error{{static declaration of 'g3' follows non-static declaration}}
+
+extern int g4; // expected-note{{previous definition}}
+static int g4; // expected-error{{static declaration of 'g4' follows non-static declaration}}
+
+__private_extern__ int g5; // expected-note{{previous definition}}
+static int g5; // expected-error{{static declaration of 'g5' follows non-static declaration}}
+
+void f0() {
+  // FIXME: Diagnose this?
+  int g6;
+  extern int g6;
+}
+
+void f1() {
+  // FIXME: Diagnose this?
+  int g7;
+  __private_extern__ int g7;
+}
+
+void f2() {
+  extern int g8; // expected-note{{previous definition}}
+  // FIXME: Improve this diagnostic.
+  int g8; // expected-error{{redefinition of 'g8'}}
+}
+
+void f3() {
+  __private_extern__ int g9; // expected-note{{previous definition}}
+  // FIXME: Improve this diagnostic.
+  int g9; // expected-error{{redefinition of 'g9'}}
+}
+
+void f4() {
+  extern int g10;
+  extern int g10;
+}
+
+void f5() {
+  __private_extern__ int g11;
+  __private_extern__ int g11;
+}
+
+void f6() {
+  // FIXME: Diagnose
+  extern int g12;
+  __private_extern__ int g12;
+}
+
+void f7() {
+  // FIXME: Diagnose
+  __private_extern__ int g13;
+  extern int g13;
+}
+
+struct s0;
+void f8() {
+  extern struct s0 g14;
+  __private_extern__ struct s0 g14;
+}
+struct s0 { int x; };
+
+void f9() {
+  extern int g15 = 0; // expected-error{{'extern' variable cannot have an initializer}}
+  // FIXME: linkage specifier in warning.
+  __private_extern__ int g16 = 0; // expected-error{{'extern' variable cannot have an initializer}}
+}
+
+extern int g17;
+int g17 = 0;
+
+extern int g18 = 0; // expected-warning{{'extern' variable has an initializer}}
+
+__private_extern__ int g19;
+int g19 = 0;
+
+// FIXME: linkage specifier in warning.
+__private_extern__ int g20 = 0; // expected-warning{{'extern' variable has an initializer}}