Centralize error reporting of improper uses of incomplete types in the
new DiagnoseIncompleteType. It provides additional information about
struct/class/union/enum types when possible, either by pointing to the
forward declaration of that type or by pointing to the definition (if
we're in the process of defining that type). 
Fixes <rdar://problem/6500531>.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@62521 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/Sema/init.c b/test/Sema/init.c
index 72586b1..abfab37 100644
--- a/test/Sema/init.c
+++ b/test/Sema/init.c
@@ -71,7 +71,8 @@
 
 // PR3001
 struct s1 s2 = {
-    .a = sizeof(struct s3), // expected-error {{invalid application of 'sizeof'}}
+    .a = sizeof(struct s3), // expected-error {{invalid application of 'sizeof'}} \
+                            // expected-note{{forward declaration of 'struct s3'}}
     .b = bogus // expected-error {{use of undeclared identifier 'bogus'}}
 }