[PATCH] D26808: [Sema] Don't allow applying address-of operator to a call to a function with __unknown_anytype return type

[Akira Hatanaka via cfe-commits]

ahatanak created this revision.
ahatanak added reviewers: doug.gregor, spyffe.
ahatanak added a subscriber: cfe-commits.

This patch fixes an assert in CodeGenFunction::EmitCallExprLValue that is triggered when the CallExpr's return type is not a reference type:

assert(E->getCallReturnType(getContext())->isReferenceType() &&

  "Can't have a scalar return unless the return type is a "
  "reference type!");

Alternatively, since it's legal to apply the address-of operator to a reference return, we can change the function return type to be a reference (in the test case, that would be double&) in RebuildUnknownAnyExpr::VisitUnaryAddrOf when compiling for C++ (but not when compiling for C).


https://reviews.llvm.org/D26808

Files:
  include/clang/Basic/DiagnosticSemaKinds.td
  lib/Sema/SemaExpr.cpp
  test/SemaCXX/unknown-anytype.cpp


Index: test/SemaCXX/unknown-anytype.cpp
===================================================================
--- test/SemaCXX/unknown-anytype.cpp
+++ test/SemaCXX/unknown-anytype.cpp
@@ -56,3 +56,15 @@
     (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;
+  }
+
+}
Index: lib/Sema/SemaExpr.cpp
===================================================================
--- lib/Sema/SemaExpr.cpp
+++ lib/Sema/SemaExpr.cpp
@@ -14773,6 +14773,13 @@
           << 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);
Index: include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- include/clang/Basic/DiagnosticSemaKinds.td
+++ include/clang/Basic/DiagnosticSemaKinds.td
@@ -8017,6 +8017,9 @@
 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<


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