caddyfile: Fix comparing if two tokens are on the same line (#5626)

* fix comparing if two tokens are on the same line

* compare tokens from copies when importing

caddyconfig/caddyfile/lexer.go

@@ -338,3 +338,28 @@ func (t Token) NumLineBreaks() int {
 }
 
 var heredocMarkerRegexp = regexp.MustCompile("^[A-Za-z0-9_-]+$")
+
+// isNextOnNewLine tests whether t2 is on a different line from t1
+func isNextOnNewLine(t1, t2 Token) bool {
+	// If the second token is from a different file,
+	// we can assume it's from a different line
+	if t1.File != t2.File {
+		return true
+	}
+
+	// If the second token is from a different import chain,
+	// we can assume it's from a different line
+	if len(t1.imports) != len(t2.imports) {
+		return true
+	}
+	for i, im := range t1.imports {
+		if im != t2.imports[i] {
+			return true
+		}
+	}
+
+	// If the first token (incl line breaks) ends
+	// on a line earlier than the next token,
+	// then the second token is on a new line
+	return t1.Line+t1.NumLineBreaks() < t2.Line
+}