nonGoOverlay map[string]string // map from non-.go source files to copied files in objdir. Nil if no overlay is used.
	traceSpan    *trace.Span
}

// BuildActionID returns the action ID section of a's build ID.
func (a *Action) BuildActionID() string { return actionID(a.buildID) }

// BuildContentID returns the content ID section of a's build ID.
func (a *Action) BuildContentID() string { return contentID(a.buildID) }

					return
				}
			}
		}()
	}

	wg.Wait()

	// Write action graph again, this time with timing information.
	writeActionGraph()
}

// buildActionID computes the action ID for a build action.
func (b *Builder) buildActionID(a *Action) cache.ActionID {
	p := a.Package
	h := cache.NewHash("build " + p.ImportPath)

	// Configuration independent of compiler toolchain.

// It reports whether the result can be satisfied from cache.
func (c *runCache) tryCache(b *work.Builder, a *work.Action) bool {
	return c.tryCacheWithID(b, a, a.Deps[0].BuildActionID())
}

func (c *runCache) tryCacheWithID(b *work.Builder, a *work.Action, id string) bool {
	if len(pkgArgs) == 0 {
		// Caching does not apply to "go test",