Allow functions to be marked "implicit return zero" and so mark main().
Codegen by initializing the return value with its LLVM type's null value.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@77288 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index 7ab7356..9b6de12 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -3501,8 +3501,11 @@
   Stmt *Body = BodyArg.takeAs<Stmt>();
   if (FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(dcl)) {
     FD->setBody(Body);
-    if (!FD->isMain())
+    if (FD->isMain())
       // C and C++ allow for main to automagically return 0.
+      // Implements C++ [basic.start.main]p5 and C99 5.1.2.2.3.
+      FD->setHasImplicitReturnZero(true);
+    else
       CheckFallThroughForFunctionDef(FD, Body);
     
     if (!FD->isInvalidDecl())