buildtags: Format only go:build lines for go 1.18+ (#211)

``` $ ./tmp/testgo161718.sh ./buildtags/ ./printer/ + go1.16.8 test ./buildtags/ ./printer/ ok github.com/mmcloughlin/avo/buildtags 0.001s ok github.com/mmcloughlin/avo/printer 0.002s + go1.17.2 test ./buildtags/ ./printer/ ok github.com/mmcloughlin/avo/buildtags 0.001s ok github.com/mmcloughlin/avo/printer 0.002s + gotip test ./buildtags/ ./printer/ ok github.com/mmcloughlin/avo/buildtags 0.001s ok github.com/mmcloughlin/avo/printer 0.002s ``` Updates #183
mmcloughlin · Oct 30, 2021 · 1d235fb · 1d235fb
1 parent c48d61f
commit 1d235fb
Showing 1 changed file with 2 additions and 1 deletion.
diff --git a/buildtags/syntax.go b/buildtags/syntax.go
@@ -33,7 +33,8 @@ func Format(t ConstraintsConvertable) (string, error) {
 	output := ""
 	for scanner.Scan() {
 		line := scanner.Text()
-		if strings.HasPrefix(line, "//") {
+		if (PlusBuildSyntaxSupported() && strings.HasPrefix(line, "// +build")) ||
+			(GoBuildSyntaxSupported() && strings.HasPrefix(line, "//go:build")) {
 			output += line + "\n"
 		}
 	}