Handle temp output names correctly (thought-machine#812)

* Use temp output names when necessary

* Handle temp names on the way back out too

* try ensurepip?

no flippin' clue why this is failing now...

.cirrus.yml

@@ -5,6 +5,6 @@ env:
   GOPROXY: https://proxy.golang.org
 
 task:
-  install_script: pkg install -y bash protobuf go git python3
+  install_script: pkg install -y bash protobuf go git python3 && python3 -m ensurepip
   bashrc_script: touch ~/.bashrc
   build_script: PLZ_ARGS="-o cache.httpurl:http://$CIRRUS_HTTP_CACHE_HOST" ./bootstrap.sh --exclude pip --exclude py2 --exclude no_cirrus

src/core/build_target.go

@@ -45,6 +45,9 @@ const CoverageFile = "test.coverage"
 // execution API requires that we specify which is which.
 const TestResultsDirLabel = "test_results_dir"
 
+// tempOutputSuffix is the suffix we attach to temporary outputs to avoid name clashes.
+const tempOutputSuffix = ".out"
+
 // A BuildTarget is a representation of a build target and all information about it;
 // its name, dependencies, build commands, etc.
 type BuildTarget struct {
@@ -510,11 +513,11 @@ func (target *BuildTarget) NamedOutputs(name string) []string {
 // filename(plz-out/tmp/) if output has the same name as the package, this avoids the name conflict issue
 func (target *BuildTarget) GetTmpOutput(parseOutput string) string {
 	if parseOutput == target.Label.PackageName {
-		return parseOutput + ".out"
+		return parseOutput + tempOutputSuffix
 	} else if target.Label.PackageName == "" && target.HasSource(parseOutput) {
 		// This also fixes the case where source and output are the same, which can happen
 		// when we're in the root directory.
-		return parseOutput + ".out"
+		return parseOutput + tempOutputSuffix
 	}
 	return parseOutput
 }
@@ -529,6 +532,19 @@ func (target *BuildTarget) GetTmpOutputAll(parseOutputs []string) []string {
 	return tmpOutputs
 }
 
+// GetRealOutput returns the real output name for a filename that might have been a temporary output
+// (i.e as returned by GetTmpOutput).
+func (target *BuildTarget) GetRealOutput(output string) string {
+	if strings.HasSuffix(output, tempOutputSuffix) {
+		real := strings.TrimSuffix(output, tempOutputSuffix)
+		// Check this isn't a file that just happens to be named the same way
+		if target.GetTmpOutput(real) == output {
+			return real
+		}
+	}
+	return output
+}
+
 // SourcePaths returns the source paths for a given set of sources.
 func (target *BuildTarget) SourcePaths(graph *BuildGraph, sources []BuildInput) []string {
 	ret := make([]string, 0, len(sources))

src/remote/remote.go

@@ -358,7 +358,7 @@ func (c *Client) Retrieve(target *core.BuildTarget) (*core.BuildMetadata, error)
 	if err := c.downloadBlobs(ctx, func(ch chan<- *blob) error {
 		defer close(ch)
 		for _, file := range resp.OutputFiles {
-			filePath := path.Join(outDir, file.Path)
+			filePath := path.Join(outDir, target.GetRealOutput(file.Path))
 			addPerms := extraPerms(file)
 			if file.Contents != nil {
 				// Inlining must have been requested. Can write it directly.

src/remote/utils.go

@@ -266,6 +266,7 @@ func outputs(target *core.BuildTarget) (files, dirs []string) {
 	outs := target.Outputs()
 	files = make([]string, 0, len(outs))
 	for _, out := range outs {
+		out = target.GetTmpOutput(out)
 		if !strings.ContainsRune(path.Base(out), '.') && !strings.HasSuffix(out, "file") {
 			dirs = append(dirs, out)
 		} else {