Fix literal obfuscation edge case.

String literals can be assigned to variables with a type that is an alias of string.

Function calls with return type string cannot be assigned to these variables.

This skips all var and const blocks which contain such assignments.

strings.go

@@ -14,17 +14,31 @@ import (
 func obfuscateLiterals(files []*ast.File) []*ast.File {
 	pre := func(cursor *astutil.Cursor) bool {
 		decl, ok := cursor.Node().(*ast.GenDecl)
-		if !ok || decl.Tok != token.CONST {
+		if !ok {
 			return true
 		}
 
 		for _, spec := range decl.Specs {
-			for _, val := range spec.(*ast.ValueSpec).Values {
+			spec, ok := spec.(*ast.ValueSpec)
+			if !ok {
+				return false
+			}
+
+			if t, ok := spec.Type.(*ast.Ident); ok {
+				if t.Name != "string" {
+					return false // if the spec has a explicit type name of non string skip it
+				}
+			}
+
+			for _, val := range spec.Values {
 				if v, ok := val.(*ast.BasicLit); !ok || v.Kind != token.STRING {
 					return false // skip the block if it contains non basic literals
 				}
 			}
 		}
+		if decl.Tok != token.CONST {
+			return true
+		}
 
 		// constants are not possible if we want to obfuscate literals, therefore
 		// move all constant blocks which only contain strings to variables
@@ -56,6 +70,8 @@ func obfuscateLiterals(files []*ast.File) []*ast.File {
 				return true // TODO: garble literals other than strings
 			}
 
+			cursor.Parent()
+
 			value, err := strconv.Unquote(x.Value)
 			if err != nil {
 				panic(fmt.Sprintf("cannot unquote string: %v", err))

testdata/scripts/strings.txt

@@ -4,7 +4,7 @@ exec ./main$exe
 cmp stderr main.stderr
 ! binsubstr main$exe 'Lorem' 'ipsum' 'dolor' 'first assign' 'second assign' 'First Line' 'Second Line' 'map value' 'to obfuscate' 'also obfuscate'
 
-binsubstr main$exe 'Skip this block,' 'also skip this'
+binsubstr main$exe 'Skip this block,' 'also skip this' 'skip typed const' 'skip typed var'
 
 [short] stop # checking that the build is reproducible is slow
 
@@ -30,6 +30,13 @@ const (
 Second Line`
 )
 
+// stringType this broke previously
+type stringType string
+
+const skipTypedConst stringType = "skip typed const"
+
+var skipTypedVar stringType = "skip typed var"
+
 const (
 	skip1 = "Skip this block,"
 	i     = 1
@@ -78,6 +85,8 @@ func main() {
 
 	println(skip1, skip2)
 
+	println(skipTypedConst, skipTypedVar)
+
 	println(i, foo, bar)
 }
 
@@ -102,4 +111,5 @@ also obfuscate
 map value
 another literal
 Skip this block, also skip this
+skip typed const skip typed var
 1 0 1