diff --git a/cc/cc.go b/cc/cc.go
index f6b1152..36b2f95 100644
--- a/cc/cc.go
+++ b/cc/cc.go
@@ -1202,8 +1202,6 @@
 		if ccDep == nil {
 			// handling for a few module types that aren't cc Module but that are also supported
 			switch depTag {
-			case android.DefaultsDepTag, android.SourceDepTag:
-				// Nothing to do
 			case genSourceDepTag:
 				if genRule, ok := dep.(genrule.SourceFileGenerator); ok {
 					depPaths.GeneratedSources = append(depPaths.GeneratedSources,
@@ -1241,8 +1239,6 @@
 				} else {
 					ctx.ModuleErrorf("module %q is not a genrule", depName)
 				}
-			default:
-				ctx.ModuleErrorf("depends on non-cc module %q", depName)
 			}
 			return
 		}
diff --git a/genrule/genrule.go b/genrule/genrule.go
index 42be88f..d03d4ee 100644
--- a/genrule/genrule.go
+++ b/genrule/genrule.go
@@ -163,8 +163,6 @@
 	if len(g.properties.Tools) > 0 {
 		ctx.VisitDirectDepsBlueprint(func(module blueprint.Module) {
 			switch ctx.OtherModuleDependencyTag(module) {
-			case android.SourceDepTag:
-				// Nothing to do
 			case hostToolDepTag:
 				tool := ctx.OtherModuleName(module)
 				var path android.OptionalPath
@@ -201,8 +199,6 @@
 				} else {
 					ctx.ModuleErrorf("host tool %q missing output file", tool)
 				}
-			default:
-				ctx.ModuleErrorf("unknown dependency on %q", ctx.OtherModuleName(module))
 			}
 		})
 	}
diff --git a/java/droiddoc.go b/java/droiddoc.go
index beaec11..b641041 100644
--- a/java/droiddoc.go
+++ b/java/droiddoc.go
@@ -422,12 +422,16 @@
 		otherName := ctx.OtherModuleName(module)
 		tag := ctx.OtherModuleDependencyTag(module)
 
-		switch dep := module.(type) {
-		case Dependency:
-			switch tag {
-			case bootClasspathTag:
+		switch tag {
+		case bootClasspathTag:
+			if dep, ok := module.(Dependency); ok {
 				deps.bootClasspath = append(deps.bootClasspath, dep.ImplementationJars()...)
-			case libTag:
+			} else {
+				panic(fmt.Errorf("unknown dependency %q for %q", otherName, ctx.ModuleName()))
+			}
+		case libTag:
+			switch dep := module.(type) {
+			case Dependency:
 				deps.classpath = append(deps.classpath, dep.ImplementationJars()...)
 				if otherName == String(j.properties.Srcs_lib) {
 					srcs := dep.(SrcDependency).CompiledSrcs()
@@ -447,12 +451,7 @@
 					}
 					deps.srcJars = append(deps.srcJars, dep.(SrcDependency).CompiledSrcJars()...)
 				}
-			default:
-				panic(fmt.Errorf("unknown dependency %q for %q", otherName, ctx.ModuleName()))
-			}
-		case SdkLibraryDependency:
-			switch tag {
-			case libTag:
+			case SdkLibraryDependency:
 				sdkVersion := String(j.properties.Sdk_version)
 				linkType := javaSdk
 				if strings.HasPrefix(sdkVersion, "system_") || strings.HasPrefix(sdkVersion, "test_") {
@@ -461,23 +460,9 @@
 					linkType = javaPlatform
 				}
 				deps.classpath = append(deps.classpath, dep.HeaderJars(linkType)...)
-			default:
-				ctx.ModuleErrorf("dependency on java_sdk_library %q can only be in libs", otherName)
-			}
-		case android.SourceFileProducer:
-			switch tag {
-			case libTag:
+			case android.SourceFileProducer:
 				checkProducesJars(ctx, dep)
 				deps.classpath = append(deps.classpath, dep.Srcs()...)
-			case android.DefaultsDepTag, android.SourceDepTag:
-				// Nothing to do
-			default:
-				ctx.ModuleErrorf("dependency on genrule %q may only be in srcs, libs", otherName)
-			}
-		default:
-			switch tag {
-			case android.DefaultsDepTag, android.SourceDepTag, droiddocTemplateTag:
-				// Nothing to do
 			default:
 				ctx.ModuleErrorf("depends on non-java module %q", otherName)
 			}