Fix PR4092 by improving error recovery in two ways:

1. In a struct field redefinition, don't mark the struct erroneous.  The
   field is erroneous, but the struct is otherwise well formed.
2. Don't emit diagnostics about functions that are known to be broken already.

Either fix is sufficient to silence the second diagnostic in the example,
but the combination is better :)

llvm-svn: 70371

2 files changed, 9 insertions, 1 deletions

diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 4427f0de1f2..14136a30b69 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -2895,6 +2895,7 @@ Sema::DeclPtrTy Sema::ActOnStartOfFunctionDef(Scope *FnBodyScope, DeclPtrTy D) {
   // (C99 6.9.1p3, C++ [dcl.fct]p6).
   QualType ResultType = FD->getResultType();
   if (!ResultType->isDependentType() && !ResultType->isVoidType() &&
+      !FD->isInvalidDecl() &&
       RequireCompleteType(FD->getLocation(), ResultType,
                           diag::err_func_def_incomplete_result))
     FD->setInvalidDecl();
@@ -3713,7 +3714,6 @@ FieldDecl *Sema::CheckFieldDecl(DeclarationName Name, QualType T,
     Diag(Loc, diag::err_duplicate_member) << II;
     Diag(PrevDecl->getLocation(), diag::note_previous_declaration);
     NewFD->setInvalidDecl();
-    Record->setInvalidDecl();
   }
 
   if (getLangOptions().CPlusPlus && !T->isPODType())
diff --git a/clang/test/Sema/struct-decl.c b/clang/test/Sema/struct-decl.c
index b288850a731..2c0945f9f86 100644
--- a/clang/test/Sema/struct-decl.c
+++ b/clang/test/Sema/struct-decl.c
@@ -33,3 +33,11 @@ struct datatag {
  char data;
 };
 
+
+// PR4092
+struct s0 {
+  char a;  // expected-note {{previous declaration is here}}
+  char a;  // expected-error {{duplicate member 'a'}}
+};
+
+struct s0 f0(void) {}