fix <rdar://problem/21110580> guard let in top level code doesn't work

We were just not injecting the vardecls into the SourceFile, so unqual name 
lookup couldn't find them later.


Swift SVN r29456

Author: lattner

lib/Parse/ParseStmt.cpp

@@ -367,6 +367,18 @@ ParserStatus Parser::parseBraceItems(SmallVectorImpl<ASTNode> &Entries,
                                        Result, Result.getEndLoc());
         TLCD->setBody(Brace);
         Entries.push_back(TLCD);
+
+        // If the parsed stmt was a GuardStmt, push the VarDecls into the
+        // Entries list, so that they can be found by unqual name lookup later.
+        if (auto guard = dyn_cast_or_null<GuardStmt>(Result.dyn_cast<Stmt*>())){
+          for (const auto &elt : guard->getCond()) {
+            if (!elt.getPatternOrNull()) continue;
+
+            elt.getPattern()->forEachVariable([&](VarDecl *VD) {
+              Entries.push_back(VD);
+            });
+          }
+        }
       }
     } else {
       SourceLoc StartLoc = Tok.getLoc();

test/Interpreter/statements.swift

@@ -41,7 +41,12 @@ for case let i? in OptionalArr where i != 3 {
 // CHECK-NEXT: 4
 // CHECK-NEXT: 5
 
+print("guard top level")
+guard let guardvalue = Optional(42) else { preconditionFailure() }
+print(guardvalue)
 
+// CHECK-LABEL: guard top level
+// CHECK-NEXT: 42
 
 print("done");
 // CHECK-LABEL: done