From d945538a36642cb0f935b268acbc32a67fae85a6 Mon Sep 17 00:00:00 2001
From: Douglas Gregor <dgregor@apple.com>
Date: Fri, 6 Aug 2010 13:50:58 +0000
Subject: [PATCH] Make sure that we diagnose attribute((overloadable))
 functions without prototypes. Fixes PR7738.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@110443 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Sema/SemaDecl.cpp    | 34 +++++++++++++++-------------------
 test/Sema/overloadable.c | 11 ++++++++++-
 2 files changed, 25 insertions(+), 20 deletions(-)

diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index d6797af31f..5cef150504 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -3548,6 +3548,20 @@ Sema::ActOnFunctionDeclarator(Scope* S, Declarator& D, DeclContext* DC,
     NewFD->addAttr(::new (Context) OverloadableAttr());
   }
 
+  if (NewFD->hasAttr<OverloadableAttr>() && 
+      !NewFD->getType()->getAs<FunctionProtoType>()) {
+    Diag(NewFD->getLocation(),
+         diag::err_attribute_overloadable_no_prototype)
+      << NewFD;
+
+    // Turn this into a variadic function with no parameters.
+    const FunctionType *FT = NewFD->getType()->getAs<FunctionType>();
+    QualType R = Context.getFunctionType(FT->getResultType(),
+                                         0, 0, true, 0, false, false, 0, 0,
+                                         FT->getExtInfo());
+    NewFD->setType(R);
+  }
+
   // If there's a #pragma GCC visibility in scope, and this isn't a class
   // member, set the visibility of this function.
   if (NewFD->getLinkage() == ExternalLinkage && !DC->isRecord())
@@ -3639,27 +3653,9 @@ void Sema::CheckFunctionDeclaration(Scope *S, FunctionDecl *NewFD,
       Redeclaration = true;
       OldDecl = Previous.getFoundDecl();
     } else {
-      if (!getLangOptions().CPlusPlus) {
+      if (!getLangOptions().CPlusPlus)
         OverloadableAttrRequired = true;
 
-        // Functions marked "overloadable" must have a prototype (that
-        // we can't get through declaration merging).
-        if (!NewFD->getType()->getAs<FunctionProtoType>()) {
-          Diag(NewFD->getLocation(),
-               diag::err_attribute_overloadable_no_prototype)
-            << NewFD;
-          Redeclaration = true;
-
-          // Turn this into a variadic function with no parameters.
-          QualType R = Context.getFunctionType(
-                     NewFD->getType()->getAs<FunctionType>()->getResultType(),
-                     0, 0, true, 0, false, false, 0, 0,
-                     FunctionType::ExtInfo());
-          NewFD->setType(R);
-          return NewFD->setInvalidDecl();
-        }
-      }
-
       switch (CheckOverload(S, NewFD, Previous, OldDecl,
                             /*NewIsUsingDecl*/ false)) {
       case Ovl_Match:
diff --git a/test/Sema/overloadable.c b/test/Sema/overloadable.c
index 28c3e4cf8c..8fb41a994c 100644
--- a/test/Sema/overloadable.c
+++ b/test/Sema/overloadable.c
@@ -41,7 +41,6 @@ double promote(float) __attribute__((__overloadable__)); // expected-note {{cand
 double promote(double) __attribute__((__overloadable__)); // expected-note {{candidate}}
 long double promote(long double) __attribute__((__overloadable__)); // expected-note {{candidate}}
 
-void promote() __attribute__((__overloadable__)); // expected-error{{'overloadable' function 'promote' must have a prototype}}
 void promote(...) __attribute__((__overloadable__, __unavailable__)); // \
     // expected-note{{candidate function}}
 
@@ -60,3 +59,13 @@ double magnitude(IntVec) __attribute__((__overloadable__));
 double test_p6600(DoubleVec d) {
   return magnitude(d) * magnitude(d);
 }
+
+// PR7738
+extern int __attribute__((overloadable)) f0(); // expected-error{{'overloadable' function 'f0' must have a prototype}}
+typedef int f1_type();
+f1_type __attribute__((overloadable)) f1; // expected-error{{'overloadable' function 'f1' must have a prototype}}
+
+void test() { 
+  f0();
+  f1();
+}
-- 
2.40.0