Address PR feedback

Specify the map size hint. Refactor the map to use struct instead of
bool.

language/go/config.go

@@ -41,10 +41,10 @@ import (
 
 var minimumRulesGoVersion = version.Version{0, 29, 0}
 
-type tagSet map[string]bool
+type tagSet map[string]struct{}
 
 func (ts tagSet) clone() tagSet {
-	c := make(tagSet)
+	c := make(tagSet, len(ts))
 	for k, v := range ts {
 		c[k] = v
 	}
@@ -189,7 +189,7 @@ func newGoConfig() *goConfig {
 		goGrpcCompilers:  defaultGoGrpcCompilers,
 		goGenerateProto:  true,
 		genericTags: []tagSet{
-			{"gc": true},
+			{"gc": struct{}{}},
 		},
 	}
 	return gc
@@ -224,7 +224,7 @@ func (gc *goConfig) setBuildTags(tags string) error {
 		var newSets []tagSet
 		for _, ts := range gc.genericTags {
 			c := ts.clone()
-			c[t] = true
+			c[t] = struct{}{}
 			newSets = append(newSets, c)
 		}
 		gc.genericTags = append(gc.genericTags, newSets...)

language/go/config_test.go

@@ -59,11 +59,19 @@ func testConfig(t *testing.T, args ...string) (*config.Config, []language.Langua
 	return c, langs, cexts
 }
 
+func newTagSet(tags ...string) tagSet {
+	ts := make(tagSet)
+	for _, t := range tags {
+		ts[t] = struct{}{}
+	}
+	return ts
+}
+
 var expectedBuildTags = []tagSet{
-	{"gc": true},
-	{"gc": true, "foo": true},
-	{"gc": true, "bar": true},
-	{"gc": true, "foo": true, "bar": true},
+	newTagSet("gc"),
+	newTagSet("gc", "foo"),
+	newTagSet("gc", "bar"),
+	newTagSet("gc", "foo", "bar"),
 }
 
 func TestCommandLine(t *testing.T) {

language/go/fileinfo.go

@@ -587,7 +587,8 @@ func checkConstraints(c *config.Config, os, arch, osSuffix, archSuffix string, t
 			return arch == tag
 		}
 
-		return ts[tag]
+		_, ok := ts[tag]
+		return ok
 	}
 
 	for _, ts := range goConf.genericTags {