Make 'raco pkg install' with no arguments install the current directory.

This is useful for telling people how to install a new pkg, from
GitHub or elsewhere: just get the files, and then do
`raco pkg install` in the relevant directory.

Also, both cabal (the Haskell package manager) and npm (the node.js
package manager) behave this way.

To explicitly get the old behavior, specify the sources as
`--pkgs pkg-srcs ...`.  This is useful in scripts, when `pkg-srcs`
might be empty.

Makefile

@@ -199,7 +199,7 @@ RACKET = racket/bin/racket $(USER_CONFIG)
 RACO = racket/bin/racket $(USER_CONFIG) -N raco -l- raco
 WIN32_RACKET = racket\racket $(USER_CONFIG)
 WIN32_RACO = racket\racket $(USER_CONFIG) -N raco -l- raco
-X_AUTO_OPTIONS = --skip-installed --deps search-auto $(JOB_OPTIONS)
+X_AUTO_OPTIONS = --skip-installed --deps search-auto --pkgs $(JOB_OPTIONS)
 USER_AUTO_OPTIONS = --scope user $(X_AUTO_OPTIONS)
 LOCAL_USER_AUTO = --catalog build/local/catalog $(USER_AUTO_OPTIONS)
 SOURCE_USER_AUTO_q = --catalog "$(SRC_CATALOG)" $(USER_AUTO_OPTIONS)

pkgs/racket-pkgs/racket-doc/pkg/scribblings/getting-started.scrbl

@@ -300,10 +300,9 @@ get started.
 Whether creating a @tech{single-collection package} or a
 @tech{multi-collection package}, the next step is to link your
 development directory as a locally installed package. Use
-@command-ref{install} in the directory where you created the
+@command-ref{install} in the @nonterm{pkg-name} directory:
-@nonterm{pkg-name} directory:
 
-@commandline{raco pkg install --link @nonterm{pkg-name}}
+@commandline{raco pkg install}
 
 If you use @command-ref{show} at this point, you'll see a line for
 @nonterm{pkg-name}. The ``Source'' column will show that it's a

pkgs/racket-pkgs/racket-doc/pkg/scribblings/pkg.scrbl

@@ -322,6 +322,9 @@ sub-commands.
      If a given @nonterm{pkg-source} is ``auto-installed'' (to satisfy some other package's
      dependency), then it is promoted to explicitly installed.
 
+     If no @nonterm{pkg-source}s are supplied, the current directory is
+     installed as a link. See the @DFlag{link} flag below for more details.
+
  The @exec{install} sub-command accepts 
  the following @nonterm{option}s:
 
@@ -377,6 +380,9 @@ sub-commands.
         of the given directory will not change for each given directory that implements a
         @tech{multi-collection package}.}
 
+  @item{@DFlag{pkgs} --- Disables default installation of the current directory when no @nonterm{pkg-source}s
+        are supplied.}
+
   @item{@DFlag{copy} --- Disables default handling of directory @tech{package sources} as links,
         and instead treats them like other sources: package content is copied to install.}
 

racket/collects/pkg/main.rkt

@@ -151,6 +151,7 @@
              #:once-each
              catalog-flags ...
              [#:bool skip-installed () ("Skip a <pkg-source> if already installed")]
+             [#:bool pkgs () ("Install only the specified packages, even when none are provided")]
              install-force-flags ...
              job-flags ...
              #:args pkg-source
@@ -159,8 +160,18 @@
               'install
               scope scope-dir installation user #f a-type
               (lambda ()
+                (when (and name (> (length pkg-source) 1))
+                  ((current-pkg-error) (format "the --name flag only makes sense with a single package source")))
                 (unless (or (not name) (package-source->name name))
                   ((current-pkg-error) (format "~e is an invalid package name" name)))
+                ;; if no sources were supplied, and `--pkgs` was not
+                ;; explicitly specified, install the current directory
+                ;; as a linked directory
+                (define-values (sources a-type*)
+                  (if (and (not pkgs) (null? pkg-source))
+                      (values (list (path->string (current-directory)))
+                              'link)
+                      (values pkg-source a-type)))
                 (define setup-collects
                   (with-pkg-lock
                    (parameterize ([current-pkg-catalogs (and catalog
@@ -173,8 +184,8 @@
                                   #:update-deps? update-deps
                                   #:strip (or (and source 'source) (and binary 'binary))
                                   #:link-dirs? link-dirs?
-                                  (for/list ([p (in-list pkg-source)])
+                                  (for/list ([p (in-list sources)])
-                                    (pkg-desc p a-type name checksum #f))))))
+                                    (pkg-desc p a-type* name checksum #f))))))
                 (setup no-setup setup-collects jobs)))]
             ;; ----------------------------------------
             [update

racket/collects/racket/HISTORY.txt

@@ -1,8 +1,9 @@
 Version 5.90.0.9
-Allow hash table chaperones and impersonators to Support efficient
+Allow hash table chaperones and impersonators to support efficient
  hash-clear and hash-clear!
 setup/collection-name: added
 syntax/unsafe/for-transform: added
+raco pkg install with no arguments installs the current directory.
 
 Version 5.90.0.6
 Added path<?, symbol<?