Don't walk into an as-of-yet-unsynthesized function body.

...and don't dump it, and don't force it just to see if an accessor is present.

Swift SVN r15830

include/swift/AST/Decl.h

@@ -3233,8 +3233,8 @@ public:
   /// have a body for this function.
   ///
   /// \sa hasBody()
-  BraceStmt *getBody() const {
-    if (getBodyKind() == BodyKind::Synthesize) {
+  BraceStmt *getBody(bool canSynthesize = true) const {
+    if (canSynthesize && getBodyKind() == BodyKind::Synthesize) {
       const_cast<AbstractFunctionDecl *>(this)->setBodyKind(BodyKind::None);
       (*Synthesizer)(const_cast<AbstractFunctionDecl *>(this));
     }