Use default user's cache dir instead of tmp for build cache

Author: cmaglie

commands/service_compile_test.go

@@ -24,8 +24,8 @@ import (
 )
 
 func TestGenBuildPath(t *testing.T) {
-	want := paths.TempDir().Join("arduino", "sketches", "ACBD18DB4CC2F85CEDEF654FCCC4A4D8")
 	srv := NewArduinoCoreServer().(*arduinoCoreServerImpl)
+	want := srv.settings.GetBuildCachePath().Join("sketches", "ACBD18DB4CC2F85CEDEF654FCCC4A4D8")
 	act := srv.getDefaultSketchBuildPath(&sketch.Sketch{FullPath: paths.New("foo")}, nil)
 	assert.True(t, act.EquivalentTo(want))
 	assert.Equal(t, "ACBD18DB4CC2F85CEDEF654FCCC4A4D8", (&sketch.Sketch{FullPath: paths.New("foo")}).Hash())

internal/cli/configuration/configuration.go

@@ -103,7 +103,14 @@ func getDefaultUserDir() string {
 
 // getDefaultBuildCacheDir returns the full path to the default build cache folder
 func getDefaultBuildCacheDir() string {
-	return paths.TempDir().Join("arduino").String()
+	var cacheDir *paths.Path
+	if p, err := os.UserCacheDir(); err == nil {
+		cacheDir = paths.New(p)
+	} else {
+		// fallback to /tmp
+		cacheDir = paths.TempDir()
+	}
+	return cacheDir.Join("arduino").String()
 }
 
 // FindConfigFlagsInArgsOrFallbackOnEnv returns the config file path using the