fmt: Accept multiple files to be formatted

Closes #718

ci/release/changelogs/next.md

@@ -4,6 +4,8 @@
 - The [Dockerfile](./docs/INSTALL.md#docker) now supports rendering PNGs [#594](https://github.com/terrastruct/d2/issues/594)
   - There was a minor breaking change as part of this where the default working directory of the Dockerfile is now `/home/debian/src` instead of `/root/src` to allow UID remapping with [`fixuid`](https://github.com/boxboat/fixuid).
 
+- `d2 fmt` accepts multiple files to be formatted [#718](https://github.com/terrastruct/d2/issues/718)
+
 #### Improvements 🧹
 
 #### Bugfixes ⛑️

ci/release/template/man/d2.1

@@ -13,7 +13,7 @@
 .Nm d2
 .Ar layout Op Ar name
 .Nm d2
-.Ar fmt Ar file.d2
+.Ar fmt Ar file.d2 ...
 .Sh DESCRIPTION
 .Nm
 compiles and renders
@@ -83,10 +83,8 @@ Print version information and exit.
 Lists available layout engine options with short help.
 .It Ar layout Op Ar name
 Display long help for a particular layout engine, including its configuration options.
-.It Ar fmt Ar file.d2
-Format
-.Ar file.d2
-.Ns .
+.It Ar fmt Ar file.d2 ...
+Format all passed files.
 .El
 .Sh SEE ALSO
 .Xr d2plugin-tala 1

fmt.go

@@ -17,12 +17,10 @@ func fmtCmd(ctx context.Context, ms *xmain.State) (err error) {
 
 	ms.Opts = xmain.NewOpts(ms.Env, ms.Log, ms.Opts.Flags.Args()[1:])
 	if len(ms.Opts.Args) == 0 {
-		return xmain.UsageErrorf("fmt must be passed the file to be formatted")
-	} else if len(ms.Opts.Args) > 1 {
-		return xmain.UsageErrorf("fmt accepts only one argument for the file to be formatted")
+		return xmain.UsageErrorf("fmt must be passed at least one file to be formatted")
 	}
 
-	inputPath := ms.Opts.Args[0]
+	for _, inputPath := range ms.Opts.Args {
 		input, err := ms.ReadPath(inputPath)
 		if err != nil {
 			return err
@@ -37,6 +35,6 @@ func fmtCmd(ctx context.Context, ms *xmain.State) (err error) {
 		if !bytes.Equal(output, input) {
 			return ms.WritePath(inputPath, output)
 		}
-
+	}
 	return nil
 }

help.go

@@ -18,7 +18,7 @@ func help(ms *xmain.State) {
 	fmt.Fprintf(ms.Stdout, `Usage:
   %[1]s [--watch=false] [--theme=0] file.d2 [file.svg | file.png]
   %[1]s layout [name]
-  %[1]s fmt file.d2
+  %[1]s fmt file.d2 ...
 
 %[1]s compiles and renders file.d2 to file.svg | file.png
 It defaults to file.svg if an output path is not provided.
@@ -33,7 +33,7 @@ Flags:
 Subcommands:
   %[1]s layout - Lists available layout engine options with short help
   %[1]s layout [name] - Display long help for a particular layout engine, including its configuration options
-  %[1]s fmt file.d2 - Format file.d2
+  %[1]s fmt file.d2 ... - Format passed files
 
 See more docs and the source code at https://oss.terrastruct.com/d2
 `, filepath.Base(ms.Name), ms.Opts.Defaults())