raco setup: make --check-pkg-deps require dependency declarations

By default, `raco setup` skips checking dependencies when a package
declares no dependencies. Make `--check-pkg-deps` check in that
case, too.

pkgs/racket-pkgs/racket-doc/scribblings/raco/setup.scrbl

@@ -180,13 +180,16 @@ flags:
   package-level dependency declarations, whether modules are declared
   by multiple packages, and whether package version dependencies are
   satisfied. Dependency checking uses compiled bytecode, associated
-  @filepath{.dep} files, and the documentation index. Dependency
-  checking is disabled by default if any collection is specified for
-  @exec{raco setup}.}
+  @filepath{.dep} files, and the documentation index. Unless
+  @DFlag{check-pkg-deps} is specified, dependency checking is disabled
+  if any collection is specified for @exec{raco setup}, and missing
+  dependencies are not treated as an error for a package that has no
+  dependency declarations.}
 
  @item{@DFlag{check-pkg-deps} --- checks package dependencies (unless
   explicitly disabled) even when specific collections are provided to
-  @exec{raco setup}. Currently, dependency checking related to
+  @exec{raco setup}, and even for packages that have no
+  dependency declarations. Currently, dependency checking related to
   documentation cross-referencing is constrained to documents among
   specified collections.}
 

racket/collects/setup/private/pkg-deps.rkt

@@ -29,7 +29,8 @@
          coll-modes
          setup-printf setup-fprintf
          check-unused? fix? verbose?
-         all-pkgs-lazily?)
+         all-pkgs-lazily?
+         must-declare-deps?)
   ;; Tables
   (define missing (make-hash))
   (define skip-pkgs (make-hash))
@@ -128,7 +129,7 @@
                                          (and i (i 'version (lambda () #f)))))))
     (define vers (cdr deps+build-deps+vers))
     (define deps+build-deps (car deps+build-deps+vers))
-    (unless deps+build-deps
+    (unless (or deps+build-deps must-declare-deps?)
       (hash-set! skip-pkgs pkg #t)
       (setup-printf #f "package declares no dependencies: ~s" pkg))
     (define deps+vers (if deps+build-deps

racket/collects/setup/setup-core.rkt

@@ -1805,7 +1805,8 @@
                                         (check-unused-dependencies)
                                         (fix-dependencies)
                                         (verbose)
-                                        (not no-specific-collections?))
+                                        (not no-specific-collections?)
+                                        (always-check-dependencies))
       (set! exit-code 1)))
 
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