Diagnose an attempt to give a deduction-guide a function body.

llvm-svn: 294397
diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index 1ae89ea..e3310b6 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -8129,6 +8129,9 @@
 
   // FIXME: Check that the return type can instantiate to a specialization of
   // the template specified as the deduction-guide's name.
+
+  if (D.isFunctionDefinition())
+    Diag(D.getIdentifierLoc(), diag::err_deduction_guide_defines_function);
 }
 
 //===----------------------------------------------------------------------===//