Revert "Fix for PR6953: per gcc, regparm and noreturn affect the compatibility of", it is breaking the builds of quite a few projects (emacs, dovecot, gnutar, bison).

llvm-svn: 102501

1 files changed, 13 insertions, 8 deletions

diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
index 868054fe0ec..4d7ea40079c 100644
--- a/clang/lib/AST/ASTContext.cpp
+++ b/clang/lib/AST/ASTContext.cpp
@@ -4311,16 +4311,21 @@ QualType ASTContext::mergeFunctionTypes(QualType lhs, QualType rhs,
     allLTypes = false;
   if (getCanonicalType(retType) != getCanonicalType(rbase->getResultType()))
     allRTypes = false;
-
-  // Check misc function attributes
+  // FIXME: double check this
+  // FIXME: should we error if lbase->getRegParmAttr() != 0 &&
+  //                           rbase->getRegParmAttr() != 0 &&
+  //                           lbase->getRegParmAttr() != rbase->getRegParmAttr()?
   FunctionType::ExtInfo lbaseInfo = lbase->getExtInfo();
   FunctionType::ExtInfo rbaseInfo = rbase->getExtInfo();
-  // Per gcc, compatible functions must have compatible regparm and noreturn
-  // attributes.
-  unsigned RegParm = lbaseInfo.getRegParm();
-  bool NoReturn = lbaseInfo.getNoReturn();
-  if (NoReturn != rbaseInfo.getNoReturn() || RegParm != rbaseInfo.getRegParm())
-    return QualType();
+  unsigned RegParm = lbaseInfo.getRegParm() == 0 ? rbaseInfo.getRegParm() :
+      lbaseInfo.getRegParm();
+  bool NoReturn = lbaseInfo.getNoReturn() || rbaseInfo.getNoReturn();
+  if (NoReturn != lbaseInfo.getNoReturn() ||
+      RegParm != lbaseInfo.getRegParm())
+    allLTypes = false;
+  if (NoReturn != rbaseInfo.getNoReturn() ||
+      RegParm != rbaseInfo.getRegParm())
+    allRTypes = false;
   CallingConv lcc = lbaseInfo.getCC();
   CallingConv rcc = rbaseInfo.getCC();
   // Compatible functions must have compatible calling conventions