[Sema] Don't allow applying address-of operator to a call to a function

with __unknown_anytype return type.

When the following code is compiled, Sema infers that the type of
__unknown_anytype is double:

extern __unknown_anytype func();
double *d = (double*)&func();

This triggers an assert in CodeGenFunction::EmitCallExprLValue because
it doesn't expect to see a call to a function with a non-reference
scalar return type.

This commit prevents the assert by making VisitUnaryAddrOf error out if
the address-of operator is applied to a call to a function with
__unknown_anytype return type.

rdar://problem/20287610

Differential revision: https://reviews.llvm.org/D26808

llvm-svn: 287410

3 files changed, 22 insertions, 0 deletions

diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 316cbe2e7da..0b459110a83 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -8031,6 +8031,9 @@ def err_unsupported_unknown_any_call : Error<
 def err_unknown_any_addrof : Error<
   "the address of a declaration with unknown type "
   "can only be cast to a pointer type">;
+def err_unknown_any_addrof_call : Error<
+  "address-of operator cannot be applied to a call to a function with "
+  "unknown return type">;
 def err_unknown_any_var_function_type : Error<
   "variable %0 with unknown type cannot be given a function type">;
 def err_unknown_any_function : Error<
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index fae8bf0f548..9d0d55e6876 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -14774,6 +14774,13 @@ namespace {
           << E->getSourceRange();
         return ExprError();
       }
+
+      if (isa<CallExpr>(E->getSubExpr())) {
+        S.Diag(E->getOperatorLoc(), diag::err_unknown_any_addrof_call)
+          << E->getSourceRange();
+        return ExprError();
+      }
+
       assert(E->getValueKind() == VK_RValue);
       assert(E->getObjectKind() == OK_Ordinary);
       E->setType(DestType);
diff --git a/clang/test/SemaCXX/unknown-anytype.cpp b/clang/test/SemaCXX/unknown-anytype.cpp
index 95ad0409340..78a01ba2d35 100644
--- a/clang/test/SemaCXX/unknown-anytype.cpp
+++ b/clang/test/SemaCXX/unknown-anytype.cpp
@@ -56,3 +56,15 @@ namespace test5 {
     (X<int>)test0(); // expected-error{{implicit instantiation of undefined template 'test5::X<int>'}}
   }
 }
+
+namespace test6 {
+  extern __unknown_anytype func();
+  extern __unknown_anytype var;
+  double *d;
+
+  void test() {
+    d = (double*)&func(); // expected-error{{address-of operator cannot be applied to a call to a function with unknown return type}}
+    d = (double*)&var;
+  }
+
+}