Compute outfile from dir in golang.Binary (#31)

* Add "autocleaning." For golang.Binary, default outfile to the basename of the input dir.

* Unwind the autoclean stuff, it needs a rethink.

clean.go

@@ -10,7 +10,7 @@ import (
 )
 
 // Clean is a Target that deletes the files named in Files when it runs.
-// Files that don't exist are silently ignored.
+// Files that already don't exist are silently ignored.
 //
 // A Clean target may be specified in YAML using the tag !Clean,
 // which introduces a sequence.
@@ -30,10 +30,16 @@ type clean struct {
 }
 
 // Run implements Target.Run.
-func (c *clean) Run(ctx context.Context, _ *Controller) error {
+func (c *clean) Run(ctx context.Context, con *Controller) error {
 	if GetDryRun(ctx) {
+		if GetVerbose(ctx) {
+			con.Indentf("  would remove %v", c.Files)
+		}
 		return nil
 	}
+	if GetVerbose(ctx) {
+		con.Indentf("  removing %v", c.Files)
+	}
 	for _, f := range c.Files {
 		err := os.Remove(f)
 		if errors.Is(err, fs.ErrNotExist) {

fab.yaml

@@ -1,7 +1,6 @@
 # Build builds the fab binary.
 Build: !go.Binary
   Dir: cmd/fab
-  Out: fab
 
 # Test runs "go test" with the race detector enabled, plus coverage reporting.
 Test: !Command
@@ -24,18 +23,20 @@ Check: !Seq
 
 # Cover produces a test-coverage profile and opens it in a browser.
 Cover: !Deps
-  Pre:
-    - !Files
-      In: !go.Deps
-        Dir: cmd/fab
-        Recursive: true
-        Tests: true
-      Out: [cover.out]
-      Target: !Command
-        Shell: go test -coverprofile cover.out ./...
+  Pre: [CoverOut]
   Post: !Command
     Shell: go tool cover -html cover.out
 
+# CoverOut produces cover.out by running "go test -coverprofile".
+CoverOut: !Files
+  In: !go.Deps
+    Dir: cmd/fab
+    Recursive: true
+    Tests: true
+  Out: [cover.out]
+  Target: !Command
+    Shell: go test -coverprofile cover.out ./...
+
 # Clean removes build-target output.
 Clean: !Clean
   - fab

golang/go.go

@@ -14,6 +14,8 @@ import (
 
 // Binary is a target describing how to compile a Go binary whose main package is in `dir`.
 // The resulting binary gets written to `outfile`.
+// If outfile is empty,
+// it defaults to the last path element of dir.
 // Additional command-line arguments for `go build` can be specified with `flags`.
 //
 // A Binary target may be specified in YAML using the tag !go.Binary,
@@ -24,7 +26,13 @@ import (
 //   - Flags: a sequence of additional command-line flags for `go build`
 //
 // Both Dir and Out are either absolute or relative to the directory containing the YAML file.
+// If Out is unspecified,
+// it defaults to the last path element of Dir.
 func Binary(dir, outfile string, flags ...string) (fab.Target, error) {
+	if outfile == "" {
+		outfile = filepath.Base(dir)
+	}
+
 	relOutfile, err := filepath.Rel(dir, outfile)
 	if err != nil {
 		return nil, errors.Wrapf(err, "getting relative path from %s to %s", dir, outfile)
@@ -63,12 +71,17 @@ func binaryDecoder(con *fab.Controller, node *yaml.Node, dir string) (fab.Target
 		return nil, errors.Wrap(err, "YAML error decoding go.Binary")
 	}
 
+	out := b.Out
+	if out == "" {
+		out = filepath.Base(b.Dir)
+	}
+
 	flags, err := fab.YAMLStringList(&b.Flags)
 	if err != nil {
 		return nil, errors.Wrap(err, "YAML error decoding go.Binary.Flags")
 	}
 
-	return Binary(con.JoinPath(dir, b.Dir), con.JoinPath(dir, b.Out), flags...)
+	return Binary(con.JoinPath(dir, b.Dir), con.JoinPath(dir, out), flags...)
 }
 
 // Deps produces the list of files involved in building the Go package in the given directory.

proto/proto.go

@@ -23,7 +23,7 @@ import (
 // includes is a list of directories in which to find .proto files;
 // otherOpts are options (other than -I / --proto_path options) for the protoc command line.
 // Typically otherOpts includes at least "--foo_out=DIR" for some target language foo.
-// This function uses [Deps] to find the dependencies of the input files.
+// This function uses [fab.Deps] to find the dependencies of the input files.
 //
 // A Proto target may be specified in YAML using the !proto.Proto tag,
 // which introduces a mapping whose fields are:

yaml.go

@@ -362,7 +362,7 @@ func YAMLStringListFromNodes(nodes []*yaml.Node) ([]string, error) {
 		yamlStringListRegistryMu.Unlock()
 
 		if !ok {
-			return nil, fmt.Errorf("unknown YAML string-list type %s", tag)
+			return nil, UnknownStringListTagError{Tag: tag}
 		}
 
 		strs, err := fn(node)