Not as conservative now, I guess

src/hash-visitor.cc

@@ -767,7 +767,7 @@ bool HashVisitor::VisitBlockDecl(const BlockDecl *Node)
 
 bool HashVisitor::VisitFunctionDecl(const FunctionDecl *Node){
 	//Ignore extern declarations
-	if(Node->getStorageClass() == StorageClass::SC_Extern || Node->getStorageClass() == StorageClass::SC_PrivateExtern || !Node->hasBody()){
+	if(Node->getStorageClass() == StorageClass::SC_Extern || Node->getStorageClass() == StorageClass::SC_PrivateExtern || !Node->isThisDeclarationADefinition()){
 		doNotHashThis = true;
 		return true;
 	}

test/tests_Moe/FD_void_unused.c

+void func(void); {{A}}
+{{B}}
+int main(){
+	return 0;
+}
+
+/*
+ * check-name: void FuncDecl unused
+ * B == A
+ */

test/tests_Moe/FD_void_used.c

+void func(void); {{A}}
+{{B}}
+int main(){
+	func(); {{A}}
+	return 0;
+}
+
+/*
+ * check-name: void FuncDecl used
+ * B != A
+ */