If consent to search is invalid, can the search proceed without a warrant?

1 In its brief, the government adopts the district court's conclusion that even if the consent to search was invalid, the seized evidence was "inevitably discoverable" because the officers could have obtained a search warrant. We note that the inevitable discovery doctrine applies to situations where illegally seized information or evidence would have been obtained from another source and does not validate all warrantless searches where the officers could have obtained a search warrant. See e.g., United States v. Ramirez-Sandoval, 872 F.2d 1392, 1400 (9th Cir.1989).