ensure selectorExpr.X is package name

see test case

.gitignore

@@ -2,3 +2,4 @@
 
 # binary
 cmd/exhaustive/exhaustive
+exhaustive

map.go

@@ -121,6 +121,16 @@ func checkMapLiterals(pass *analysis.Pass, inspect *inspector.Inspector, comment
 							if !ok {
 								continue
 							}
+
+							// ensure X is package identifier
+							ident, ok := selExpr.X.(*ast.Ident)
+							if !ok {
+								continue
+							}
+							if !isPackageNameIdentifier(pass, ident) {
+								continue
+							}
+
 							delete(hitlist, selExpr.Sel.Name)
 						}
 					}

switch.go

@@ -105,6 +105,16 @@ func checkSwitchStatements(pass *analysis.Pass, inspect *inspector.Inspector, co
 					if !ok {
 						continue
 					}
+
+					// ensure X is package identifier
+					ident, ok := selExpr.X.(*ast.Ident)
+					if !ok {
+						continue
+					}
+					if !isPackageNameIdentifier(pass, ident) {
+						continue
+					}
+
 					delete(hitlist, selExpr.Sel.Name)
 				}
 			}
@@ -120,6 +130,15 @@ func checkSwitchStatements(pass *analysis.Pass, inspect *inspector.Inspector, co
 	})
 }
 
+func isPackageNameIdentifier(pass *analysis.Pass, ident *ast.Ident) bool {
+	obj := pass.TypesInfo.ObjectOf(ident)
+	if obj == nil {
+		return false
+	}
+	_, ok := obj.(*types.PkgName)
+	return ok
+}
+
 func hitlistFromEnumMembers(enumMembers []string, checkUnexported bool) map[string]struct{} {
 	hitlist := make(map[string]struct{})
 	for _, m := range enumMembers {

testdata/playground/exp/exp.go

@@ -0,0 +1,24 @@
+package exp
+
+// NOTE: Feel free to delete code below. This is a temporary scratchpad for use
+// when working on bugfixes or new code for exhaustive.
+
+import "github.com/nishanths/exhaustive/testdata/playground/x"
+
+func _o() {
+	// Selector isn't of the form "enumPkg.enumMember"
+
+	type holdsW struct {
+		W x.Direction
+	}
+
+	var d x.Direction
+	var h holdsW
+
+	switch d {
+	case x.N:
+	case x.E:
+	case x.S:
+	case h.W:
+	}
+}

testdata/src/switch/x/switch.go

@@ -109,3 +109,20 @@ func _n() {
 	case Desc:
 	}
 }
+
+func _o() {
+	// Selector isn't of the form "enumPkg.enumMember"
+
+	type holdsMollusca struct {
+		Mollusca bar.Phylum // can hold any Phylum value
+	}
+
+	var p bar.Phylum
+	var h holdsMollusca
+
+	switch p { // want "missing cases in switch of type bar.Phylum: Mollusca"
+	case bar.Chordata:
+	case bar.Echinodermata:
+	case h.Mollusca:
+	}
+}