bit(needCgoHdr, b.needCgoHdr(a)) |
		bit(needVet, a.needVet) |
		bit(needCovMetaFile, needCovMeta) |
		bit(needCompiledGoFiles, b.NeedCompiledGoFiles)

	if !p.BinaryOnly {
		if b.useCache(a, b.buildActionID(a), p.Target, need&needBuild != 0) {
			// We found the main output in the cache.
			// If we don't need any other outputs, we can stop.

//	    StaleReason    string   // explanation for Stale==true
//	    Root           string   // Go root or Go path dir containing this package
//	    ConflictDir    string   // this directory shadows Dir in $GOPATH
//	    BinaryOnly     bool     // binary-only package (no longer supported)
//	    ForTest        string   // package is only for use in named test
//	    Export         string   // file containing export data (when using -export)