From 63bc848f79cc573178cf83ec7870492df6140ce9 Mon Sep 17 00:00:00 2001
From: Matthew Flatt <mflatt@racket-lang.org>
Date: Tue, 17 Dec 2019 13:33:31 -0700
Subject: [PATCH] expander: another approach to fixing nested instantiation

Mostly reverts ee4ceb7ae4 and tries a different approach. The prevoius
approach did not handle the case where the module begin instantiated
was tiggered by a module at a different (higher) phase.

Closes #2981
---
 .../racket-test-core/tests/racket/module.rktl |  34 ++
 racket/src/expander/eval/module.rkt           |   8 +-
 racket/src/expander/expand/context.rkt        |   9 +-
 racket/src/expander/expand/local-expand.rkt   |   3 +-
 racket/src/expander/namespace/module.rkt      |  13 +-
 racket/src/racket/src/startup.inc             | 307 ++++++++++--------
 6 files changed, 223 insertions(+), 151 deletions(-)

diff --git a/pkgs/racket-test-core/tests/racket/module.rktl b/pkgs/racket-test-core/tests/racket/module.rktl
index f395307975..f9b140f252 100644
--- a/pkgs/racket-test-core/tests/racket/module.rktl
+++ b/pkgs/racket-test-core/tests/racket/module.rktl
@@ -3143,6 +3143,40 @@ case of module-leve bindings; it doesn't cover local bindings.
   (test (void) namespace-require ''lang-is-imports-uses-local-expand)
   (test #t namespace? (module->namespace ''lang-is-imports-uses-local-expand)))
 
+;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; Similar to previous, but with a `for-template` in the mix
+
+(module uses-local-expand-at-phase-1-instantiation-again racket/base
+  (require (for-syntax racket/base
+                       (for-syntax racket/base)))
+  (provide (for-syntax true))
+  (struct Π- (X))
+  (begin-for-syntax
+    (define TY/internal+ (local-expand #'Π- 'expression null))
+    (define true (lambda (x) #t))))
+
+(module imports-uses-local-expand-at-phase-1-instantiation-again racket/base
+  (require (for-syntax racket/base)
+           'uses-local-expand-at-phase-1-instantiation-again)
+  (provide #%module-begin)
+  (define-for-syntax predicate true))
+
+(module local-expand-test2-reflect racket/base
+  (require (for-template 'uses-local-expand-at-phase-1-instantiation-again))
+  (define x true))
+
+(module local-expand-test2 racket/base
+  (provide #%module-begin)
+  (require 'imports-uses-local-expand-at-phase-1-instantiation-again
+           (for-syntax 'local-expand-test2-reflect)))
+
+(module lang-is-local-expand-test2 'local-expand-test2)
+
+(let ()
+  ;; important that both of these are in the same top-level evaluation:
+  (test (void) namespace-require ''lang-is-local-expand-test2)
+  (test #t namespace? (module->namespace ''lang-is-local-expand-test2)))
+
 ;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; Check order of checking for redefinition of a constant
 
diff --git a/racket/src/expander/eval/module.rkt b/racket/src/expander/eval/module.rkt
index 408688b909..29c603be0c 100644
--- a/racket/src/expander/eval/module.rkt
+++ b/racket/src/expander/eval/module.rkt
@@ -221,7 +221,13 @@
                                      (define ns-1 (namespace->namespace-at-phase ns (phase+ phase-shift (sub1 phase-level))))
                                      (parameterize ([current-namespace ns])
                                        (parameterize-like
-                                        #:with ([current-expand-context (delay (make-expand-context ns-1))]
+                                        #:with ([current-expand-context (delay (make-expand-context
+                                                                                ns-1
+                                                                                ;; Turn off on-demand instantiation, because
+                                                                                ;; we're already trying to instantiate modules,
+                                                                                ;; and anything that should be relevant by being
+                                                                                ;; imported here should be instantiated already:
+                                                                                #:skip-visit-available? #t))]
                                                 [current-module-code-inspector insp])
                                         (instantiate-body)))]))))))
 
diff --git a/racket/src/expander/expand/context.rkt b/racket/src/expander/expand/context.rkt
index a3823e76b6..882804892d 100644
--- a/racket/src/expander/expand/context.rkt
+++ b/racket/src/expander/expand/context.rkt
@@ -71,13 +71,15 @@
           for-serializable? ; accumulate submodules as serializable?
           to-correlated-linklet? ; compile to machine-independent linklets?
           normalize-locals? ; forget original local-variable names
-          should-not-encounter-macros?)) ; #t when "expanding" to parse
+          should-not-encounter-macros? ; #t when "expanding" to parse
+          skip-visit-available?)) ; avoid instantiation cycles
 
 (define (make-expand-context ns
                              #:to-parsed? [to-parsed? #f]
                              #:for-serializable? [for-serializable? #f]
                              #:to-correlated-linklet? [to-correlated-linklet? #f]
-                             #:observer [observer #f])
+                             #:observer [observer #f]
+                             #:skip-visit-available? [skip-visit-available? #f])
   (define root-ctx (namespace-get-root-expand-ctx ns))
   (expand-context (root-expand-context-self-mpi root-ctx)
                   (root-expand-context-module-scopes root-ctx)
@@ -120,7 +122,8 @@
                   for-serializable?
                   to-correlated-linklet?
                   to-correlated-linklet? ; normalize-locals?
-                  #f))
+                  #f
+                  skip-visit-available?))
 
 (define (copy-root-expand-context ctx root-ctx)
   (struct*-copy expand-context ctx
diff --git a/racket/src/expander/expand/local-expand.rkt b/racket/src/expander/expand/local-expand.rkt
index 0bfc85403b..babd60dcf0 100644
--- a/racket/src/expander/expand/local-expand.rkt
+++ b/racket/src/expander/expand/local-expand.rkt
@@ -111,7 +111,8 @@
                                                 #:track-to-be-defined? track-to-be-defined?))
 
    (without-expand-context
-    (namespace-visit-available-modules! (expand-context-namespace ctx) phase))
+    (unless (expand-context-skip-visit-available? ctx)
+      (namespace-visit-available-modules! (expand-context-namespace ctx) phase)))
 
    (log-expand local-ctx 'enter-local s)
    (define input-s (add-intdef-scopes (flip-introduction-scopes s ctx) intdefs))
diff --git a/racket/src/expander/namespace/module.rkt b/racket/src/expander/namespace/module.rkt
index b8cc5d60c4..58c0063464 100644
--- a/racket/src/expander/namespace/module.rkt
+++ b/racket/src/expander/namespace/module.rkt
@@ -139,7 +139,7 @@
 (struct module-instance (namespace
                          module                        ; can be #f for the module being expanded
                          [shifted-requires #:mutable]  ; computed on demand; shifted from `module-requires`
-                         phase-level-to-state          ; phase-level -> #f, 'available, 'trying-to-start, or 'started
+                         phase-level-to-state          ; phase-level -> #f, 'available, or 'started
                          [made-available? #:mutable]   ; no #f in `phase-level-to-state`?
                          [attached? #:mutable]         ; whether the instance has been attached elsewhere
                          data-box)                     ; for use by module implementation
@@ -417,9 +417,7 @@
    (define instance-phase (namespace-0-phase m-ns))
    (define run-phase-level (phase- run-phase instance-phase))
    (unless (and (or skip-run?
-                    (let ([v (small-hash-ref (module-instance-phase-level-to-state mi) run-phase-level #f)])
-                      (or (eq? 'started v)
-                          (eq? 'trying-to-start v))))
+                    (eq? 'started (small-hash-ref (module-instance-phase-level-to-state mi) run-phase-level #f)))
                 (or (not otherwise-available?)
                     (module-instance-made-available? mi)))
      ;; Something to do...
@@ -433,13 +431,6 @@
      (when (hash-ref seen mi #f)
        (error 'require "import cycle detected during module instantiation"))
 
-     (unless (or skip-run?
-                 (eq? (small-hash-ref (module-instance-phase-level-to-state mi) run-phase-level #f) 'started))
-       ;; In case instantiating imported modules does something that triggers
-       ;; a force of available modules, make sure we don't try to instantiate
-       ;; while we're in the process of instantiating:
-       (small-hash-set! (module-instance-phase-level-to-state mi) run-phase-level 'trying-to-start))
-
      ;; If we haven't shifted required mpis already, do that
      (unless (module-instance-shifted-requires mi)
        (set-module-instance-shifted-requires!
diff --git a/racket/src/racket/src/startup.inc b/racket/src/racket/src/startup.inc
index a7a2387dcb..021795387c 100644
--- a/racket/src/racket/src/startup.inc
+++ b/racket/src/racket/src/startup.inc
@@ -68,10 +68,10 @@ static const char *startup_source =
 "(1/use-compiled-file-check use-compiled-file-check)"
 "(1/use-compiled-file-paths use-compiled-file-paths)"
 "(1/use-user-specific-search-paths use-user-specific-search-paths))"
+"(define-values(call/ec) call-with-escape-continuation)"
 "(define-values"
 "(qq-append)"
 "  (lambda (a_0 b_0) (begin (if (list? a_0) (append a_0 b_0) (raise-argument-error 'unquote-splicing \"list?\" a_0)))))"
-"(define-values(call/ec) call-with-escape-continuation)"
 "(define-values"
 "(fixnum-for-every-system?)"
 "(lambda(v_0)(begin(if(fixnum? v_0)(if(fx>= v_0 -536870912)(fx<= v_0 536870911) #f) #f))))"
@@ -14207,13 +14207,12 @@ static const char *startup_source =
 "(if(if(let-values(((or-part_0) skip-run?_0))"
 "(if or-part_0"
 " or-part_0"
-"(let-values(((v_0)"
+"(eq?"
+" 'started"
 "(small-hash-ref"
 "(module-instance-phase-level-to-state mi_0)"
 " run-phase-level_0"
-" #f)))"
-"(let-values(((or-part_1)(eq? 'started v_0)))"
-"(if or-part_1 or-part_1(eq? 'trying-to-start v_0))))))"
+" #f))))"
 "(let-values(((or-part_0)(not otherwise-available?_0)))"
 "(if or-part_0 or-part_0(module-instance-made-available? mi_0)))"
 " #f)"
@@ -14240,21 +14239,6 @@ static const char *startup_source =
 " 'require"
 "                                                     \"import cycle detected during module instantiation\"))"
 "(void))"
-"(if(let-values(((or-part_0) skip-run?_0))"
-"(if or-part_0"
-" or-part_0"
-"(eq?"
-"(small-hash-ref"
-"(module-instance-phase-level-to-state mi_0)"
-" run-phase-level_0"
-" #f)"
-" 'started)))"
-"(void)"
-"(let-values()"
-"(small-hash-set!"
-"(module-instance-phase-level-to-state mi_0)"
-" run-phase-level_0"
-" 'trying-to-start)))"
 "(if(module-instance-shifted-requires mi_0)"
 "(void)"
 "(let-values()"
@@ -15552,20 +15536,21 @@ static const char *startup_source =
 " expand-context/inner-for-serializable?"
 " expand-context/inner-to-correlated-linklet?"
 " expand-context/inner-normalize-locals?"
-" expand-context/inner-should-not-encounter-macros?)"
+" expand-context/inner-should-not-encounter-macros?"
+" expand-context/inner-skip-visit-available?)"
 "(let-values(((struct:_0 make-_0 ?_0 -ref_0 -set!_0)"
 "(let-values()"
 "(let-values()"
 "(make-struct-type"
 " 'expand-context/inner"
 " struct:root-expand-context/inner"
-" 21"
+" 22"
 " 0"
 " #f"
 "(list(cons prop:authentic #t))"
 "(current-inspector)"
 " #f"
-" '(0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20)"
+" '(0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21)"
 " #f"
 " 'expand-context/inner)))))"
 "(values"
@@ -15592,7 +15577,8 @@ static const char *startup_source =
 "(make-struct-field-accessor -ref_0 17 'for-serializable?)"
 "(make-struct-field-accessor -ref_0 18 'to-correlated-linklet?)"
 "(make-struct-field-accessor -ref_0 19 'normalize-locals?)"
-"(make-struct-field-accessor -ref_0 20 'should-not-encounter-macros?))))"
+"(make-struct-field-accessor -ref_0 20 'should-not-encounter-macros?)"
+"(make-struct-field-accessor -ref_0 21 'skip-visit-available?))))"
 "(define-values"
 "(expand-context/make)"
 "(lambda(self-mpi_0"
@@ -15636,7 +15622,8 @@ static const char *startup_source =
 " for-serializable?_0"
 " to-correlated-linklet?_0"
 " normalize-locals?_0"
-" should-not-encounter-macros?_0)"
+" should-not-encounter-macros?_0"
+" skip-visit-available?_0)"
 "(begin"
 "(expand-context/outer1.1"
 "(expand-context/inner2.1"
@@ -15667,7 +15654,8 @@ static const char *startup_source =
 " for-serializable?_0"
 " to-correlated-linklet?_0"
 " normalize-locals?_0"
-" should-not-encounter-macros?_0)"
+" should-not-encounter-macros?_0"
+" skip-visit-available?_0)"
 " post-expansion_0"
 " use-site-scopes_0"
 " frame-id_0"
@@ -15763,15 +15751,19 @@ static const char *startup_source =
 "(expand-context-should-not-encounter-macros?)"
 "(lambda(v_0)(begin(expand-context/inner-should-not-encounter-macros?(root-expand-context/outer-inner v_0)))))"
 "(define-values"
+"(expand-context-skip-visit-available?)"
+"(lambda(v_0)(begin(expand-context/inner-skip-visit-available?(root-expand-context/outer-inner v_0)))))"
+"(define-values"
 "(make-expand-context.1)"
-"(lambda(for-serializable?4_0 observer6_0 to-correlated-linklet?5_0 to-parsed?3_0 ns11_0)"
+"(lambda(for-serializable?4_0 observer6_0 skip-visit-available?7_0 to-correlated-linklet?5_0 to-parsed?3_0 ns13_0)"
 "(begin"
 " 'make-expand-context"
-"(let-values(((ns_0) ns11_0))"
+"(let-values(((ns_0) ns13_0))"
 "(let-values(((to-parsed?_0) to-parsed?3_0))"
 "(let-values(((for-serializable?_0) for-serializable?4_0))"
 "(let-values(((to-correlated-linklet?_0) to-correlated-linklet?5_0))"
 "(let-values(((observer_0) observer6_0))"
+"(let-values(((skip-visit-available?_0) skip-visit-available?7_0))"
 "(let-values()"
 "(let-values(((root-ctx_0)(namespace-get-root-expand-ctx ns_0)))"
 "(expand-context/make"
@@ -15816,7 +15808,8 @@ static const char *startup_source =
 " for-serializable?_0"
 " to-correlated-linklet?_0"
 " to-correlated-linklet?_0"
-" #f)))))))))))"
+" #f"
+" skip-visit-available?_0))))))))))))"
 "(define-values"
 "(copy-root-expand-context)"
 "(lambda(ctx_0 root-ctx_0)"
@@ -15824,29 +15817,29 @@ static const char *startup_source =
 "(let-values(((v_0) ctx_0))"
 "(let-values(((the-struct_0) v_0))"
 "(if(expand-context/outer? the-struct_0)"
-"(let-values(((post-expansion23_0)(root-expand-context-post-expansion root-ctx_0))"
-"((use-site-scopes24_0)(root-expand-context-use-site-scopes root-ctx_0))"
-"((frame-id25_0)(root-expand-context-frame-id root-ctx_0))"
-"((binding-layer26_0)(root-expand-context-frame-id root-ctx_0))"
-"((inner27_0)"
+"(let-values(((post-expansion25_0)(root-expand-context-post-expansion root-ctx_0))"
+"((use-site-scopes26_0)(root-expand-context-use-site-scopes root-ctx_0))"
+"((frame-id27_0)(root-expand-context-frame-id root-ctx_0))"
+"((binding-layer28_0)(root-expand-context-frame-id root-ctx_0))"
+"((inner29_0)"
 "(let-values(((the-struct_1)(root-expand-context/outer-inner v_0)))"
 "(if(expand-context/inner? the-struct_1)"
-"(let-values(((self-mpi28_0)(root-expand-context-self-mpi root-ctx_0))"
-"((module-scopes29_0)(root-expand-context-module-scopes root-ctx_0))"
-"((top-level-bind-scope30_0)"
+"(let-values(((self-mpi30_0)(root-expand-context-self-mpi root-ctx_0))"
+"((module-scopes31_0)(root-expand-context-module-scopes root-ctx_0))"
+"((top-level-bind-scope32_0)"
 "(root-expand-context-top-level-bind-scope root-ctx_0))"
-"((all-scopes-stx31_0)(root-expand-context-all-scopes-stx root-ctx_0))"
-"((defined-syms32_0)(root-expand-context-defined-syms root-ctx_0))"
-"((counter33_0)(root-expand-context-counter root-ctx_0))"
-"((lift-key34_0)(root-expand-context-lift-key root-ctx_0)))"
+"((all-scopes-stx33_0)(root-expand-context-all-scopes-stx root-ctx_0))"
+"((defined-syms34_0)(root-expand-context-defined-syms root-ctx_0))"
+"((counter35_0)(root-expand-context-counter root-ctx_0))"
+"((lift-key36_0)(root-expand-context-lift-key root-ctx_0)))"
 "(expand-context/inner2.1"
-" self-mpi28_0"
-" module-scopes29_0"
-" top-level-bind-scope30_0"
-" all-scopes-stx31_0"
-" defined-syms32_0"
-" counter33_0"
-" lift-key34_0"
+" self-mpi30_0"
+" module-scopes31_0"
+" top-level-bind-scope32_0"
+" all-scopes-stx33_0"
+" defined-syms34_0"
+" counter35_0"
+" lift-key36_0"
 "(expand-context/inner-to-parsed? the-struct_1)"
 "(expand-context/inner-phase the-struct_1)"
 "(expand-context/inner-namespace the-struct_1)"
@@ -15867,18 +15860,19 @@ static const char *startup_source =
 "(expand-context/inner-for-serializable? the-struct_1)"
 "(expand-context/inner-to-correlated-linklet? the-struct_1)"
 "(expand-context/inner-normalize-locals? the-struct_1)"
-"(expand-context/inner-should-not-encounter-macros? the-struct_1)))"
+"(expand-context/inner-should-not-encounter-macros? the-struct_1)"
+"(expand-context/inner-skip-visit-available? the-struct_1)))"
 "                              (raise-argument-error 'struct-copy \"expand-context/inner?\" the-struct_1)))))"
 "(expand-context/outer1.1"
-" inner27_0"
-" post-expansion23_0"
-" use-site-scopes24_0"
-" frame-id25_0"
+" inner29_0"
+" post-expansion25_0"
+" use-site-scopes26_0"
+" frame-id27_0"
 "(expand-context/outer-context the-struct_0)"
 "(expand-context/outer-env the-struct_0)"
 "(expand-context/outer-scopes the-struct_0)"
 "(expand-context/outer-def-ctx-scopes the-struct_0)"
-" binding-layer26_0"
+" binding-layer28_0"
 "(expand-context/outer-reference-records the-struct_0)"
 "(expand-context/outer-only-immediate? the-struct_0)"
 "(expand-context/outer-need-eventually-defined the-struct_0)"
@@ -15892,11 +15886,11 @@ static const char *startup_source =
 "(lambda()(begin(continuation-mark-set-first #f current-expand-context default-val.1$1 root-tag))))"
 "(define-values"
 "(get-current-expand-context.1)"
-"(lambda(fail-ok?13_0 who15_0)"
+"(lambda(fail-ok?15_0 who17_0)"
 "(begin"
 " 'get-current-expand-context"
-"(let-values(((who_0) who15_0))"
-"(let-values(((fail-ok?_0) fail-ok?13_0))"
+"(let-values(((who_0) who17_0))"
+"(let-values(((fail-ok?_0) fail-ok?15_0))"
 "(let-values()"
 "(let-values(((or-part_0)(force(current-expand-context))))"
 "              (if or-part_0 or-part_0 (if fail-ok?_0 #f (raise-arguments-error who_0 \"not currently expanding\"))))))))))"
@@ -15922,16 +15916,16 @@ static const char *startup_source =
 "(let-values(((v_0) ctx_0))"
 "(let-values(((the-struct_0) v_0))"
 "(if(expand-context/outer? the-struct_0)"
-"(let-values(((context35_0) 'expression)"
-"((name36_0) #f)"
-"((post-expansion37_0) #f)"
-"((inner38_0)(root-expand-context/outer-inner v_0)))"
+"(let-values(((context37_0) 'expression)"
+"((name38_0) #f)"
+"((post-expansion39_0) #f)"
+"((inner40_0)(root-expand-context/outer-inner v_0)))"
 "(expand-context/outer1.1"
-" inner38_0"
-" post-expansion37_0"
+" inner40_0"
+" post-expansion39_0"
 "(root-expand-context/outer-use-site-scopes the-struct_0)"
 "(root-expand-context/outer-frame-id the-struct_0)"
-" context35_0"
+" context37_0"
 "(expand-context/outer-env the-struct_0)"
 "(expand-context/outer-scopes the-struct_0)"
 "(expand-context/outer-def-ctx-scopes the-struct_0)"
@@ -15941,7 +15935,7 @@ static const char *startup_source =
 "(expand-context/outer-need-eventually-defined the-struct_0)"
 "(expand-context/outer-current-introduction-scopes the-struct_0)"
 "(expand-context/outer-current-use-scopes the-struct_0)"
-" name36_0))"
+" name38_0))"
 "                (raise-argument-error 'struct-copy \"expand-context/outer?\" the-struct_0)))))))))"
 "(define-values"
 "(as-begin-expression-context)"
@@ -15953,39 +15947,7 @@ static const char *startup_source =
 "(let-values(((v_0) ctx_0))"
 "(let-values(((the-struct_0) v_0))"
 "(if(expand-context/outer? the-struct_0)"
-"(let-values(((name39_0) #f)((inner40_0)(root-expand-context/outer-inner v_0)))"
-"(expand-context/outer1.1"
-" inner40_0"
-"(root-expand-context/outer-post-expansion the-struct_0)"
-"(root-expand-context/outer-use-site-scopes the-struct_0)"
-"(root-expand-context/outer-frame-id the-struct_0)"
-"(expand-context/outer-context the-struct_0)"
-"(expand-context/outer-env the-struct_0)"
-"(expand-context/outer-scopes the-struct_0)"
-"(expand-context/outer-def-ctx-scopes the-struct_0)"
-"(expand-context/outer-binding-layer the-struct_0)"
-"(expand-context/outer-reference-records the-struct_0)"
-"(expand-context/outer-only-immediate? the-struct_0)"
-"(expand-context/outer-need-eventually-defined the-struct_0)"
-"(expand-context/outer-current-introduction-scopes the-struct_0)"
-"(expand-context/outer-current-use-scopes the-struct_0)"
-" name39_0))"
-"                (raise-argument-error 'struct-copy \"expand-context/outer?\" the-struct_0)))))))))"
-"(define-values"
-"(as-tail-context.1)"
-"(lambda(wrt17_0 ctx19_0)"
-"(begin"
-" 'as-tail-context"
-"(let-values(((ctx_0) ctx19_0))"
-"(let-values(((wrt-ctx_0) wrt17_0))"
-"(let-values()"
-"(if(expand-context-name wrt-ctx_0)"
-"(let-values()"
-"(let-values(((v_0) ctx_0))"
-"(let-values(((the-struct_0) v_0))"
-"(if(expand-context/outer? the-struct_0)"
-"(let-values(((name41_0)(expand-context-name wrt-ctx_0))"
-"((inner42_0)(root-expand-context/outer-inner v_0)))"
+"(let-values(((name41_0) #f)((inner42_0)(root-expand-context/outer-inner v_0)))"
 "(expand-context/outer1.1"
 " inner42_0"
 "(root-expand-context/outer-post-expansion the-struct_0)"
@@ -16002,18 +15964,22 @@ static const char *startup_source =
 "(expand-context/outer-current-introduction-scopes the-struct_0)"
 "(expand-context/outer-current-use-scopes the-struct_0)"
 " name41_0))"
-"                      (raise-argument-error 'struct-copy \"expand-context/outer?\" the-struct_0)))))"
-"(let-values() ctx_0))))))))"
+"                (raise-argument-error 'struct-copy \"expand-context/outer?\" the-struct_0)))))))))"
 "(define-values"
-"(as-named-context)"
-"(lambda(ctx_0 ids_0)"
+"(as-tail-context.1)"
+"(lambda(wrt19_0 ctx21_0)"
 "(begin"
-"(if(if(pair? ids_0)(null?(cdr ids_0)) #f)"
+" 'as-tail-context"
+"(let-values(((ctx_0) ctx21_0))"
+"(let-values(((wrt-ctx_0) wrt19_0))"
+"(let-values()"
+"(if(expand-context-name wrt-ctx_0)"
 "(let-values()"
 "(let-values(((v_0) ctx_0))"
 "(let-values(((the-struct_0) v_0))"
 "(if(expand-context/outer? the-struct_0)"
-"(let-values(((name43_0)(car ids_0))((inner44_0)(root-expand-context/outer-inner v_0)))"
+"(let-values(((name43_0)(expand-context-name wrt-ctx_0))"
+"((inner44_0)(root-expand-context/outer-inner v_0)))"
 "(expand-context/outer1.1"
 " inner44_0"
 "(root-expand-context/outer-post-expansion the-struct_0)"
@@ -16030,6 +15996,34 @@ static const char *startup_source =
 "(expand-context/outer-current-introduction-scopes the-struct_0)"
 "(expand-context/outer-current-use-scopes the-struct_0)"
 " name43_0))"
+"                      (raise-argument-error 'struct-copy \"expand-context/outer?\" the-struct_0)))))"
+"(let-values() ctx_0))))))))"
+"(define-values"
+"(as-named-context)"
+"(lambda(ctx_0 ids_0)"
+"(begin"
+"(if(if(pair? ids_0)(null?(cdr ids_0)) #f)"
+"(let-values()"
+"(let-values(((v_0) ctx_0))"
+"(let-values(((the-struct_0) v_0))"
+"(if(expand-context/outer? the-struct_0)"
+"(let-values(((name45_0)(car ids_0))((inner46_0)(root-expand-context/outer-inner v_0)))"
+"(expand-context/outer1.1"
+" inner46_0"
+"(root-expand-context/outer-post-expansion the-struct_0)"
+"(root-expand-context/outer-use-site-scopes the-struct_0)"
+"(root-expand-context/outer-frame-id the-struct_0)"
+"(expand-context/outer-context the-struct_0)"
+"(expand-context/outer-env the-struct_0)"
+"(expand-context/outer-scopes the-struct_0)"
+"(expand-context/outer-def-ctx-scopes the-struct_0)"
+"(expand-context/outer-binding-layer the-struct_0)"
+"(expand-context/outer-reference-records the-struct_0)"
+"(expand-context/outer-only-immediate? the-struct_0)"
+"(expand-context/outer-need-eventually-defined the-struct_0)"
+"(expand-context/outer-current-introduction-scopes the-struct_0)"
+"(expand-context/outer-current-use-scopes the-struct_0)"
+" name45_0))"
 "                (raise-argument-error 'struct-copy \"expand-context/outer?\" the-struct_0)))))"
 "(let-values() ctx_0)))))"
 "(define-values"
@@ -16039,12 +16033,12 @@ static const char *startup_source =
 "(let-values(((v_0) ctx_0))"
 "(let-values(((the-struct_0) v_0))"
 "(if(expand-context/outer? the-struct_0)"
-"(let-values(((inner45_0)"
+"(let-values(((inner47_0)"
 "(let-values(((the-struct_1)(root-expand-context/outer-inner v_0)))"
 "(if(expand-context/inner? the-struct_1)"
-"(let-values(((to-parsed?46_0) #t)"
-"((observer47_0) #f)"
-"((should-not-encounter-macros?48_0) #t))"
+"(let-values(((to-parsed?48_0) #t)"
+"((observer49_0) #f)"
+"((should-not-encounter-macros?50_0) #t))"
 "(expand-context/inner2.1"
 "(root-expand-context/inner-self-mpi the-struct_1)"
 "(root-expand-context/inner-module-scopes the-struct_1)"
@@ -16053,7 +16047,7 @@ static const char *startup_source =
 "(root-expand-context/inner-defined-syms the-struct_1)"
 "(root-expand-context/inner-counter the-struct_1)"
 "(root-expand-context/inner-lift-key the-struct_1)"
-" to-parsed?46_0"
+" to-parsed?48_0"
 "(expand-context/inner-phase the-struct_1)"
 "(expand-context/inner-namespace the-struct_1)"
 "(expand-context/inner-just-once? the-struct_1)"
@@ -16069,14 +16063,15 @@ static const char *startup_source =
 "(expand-context/inner-require-lifts the-struct_1)"
 "(expand-context/inner-to-module-lifts the-struct_1)"
 "(expand-context/inner-requires+provides the-struct_1)"
-" observer47_0"
+" observer49_0"
 "(expand-context/inner-for-serializable? the-struct_1)"
 "(expand-context/inner-to-correlated-linklet? the-struct_1)"
 "(expand-context/inner-normalize-locals? the-struct_1)"
-" should-not-encounter-macros?48_0))"
+" should-not-encounter-macros?50_0"
+"(expand-context/inner-skip-visit-available? the-struct_1)))"
 "                              (raise-argument-error 'struct-copy \"expand-context/inner?\" the-struct_1)))))"
 "(expand-context/outer1.1"
-" inner45_0"
+" inner47_0"
 "(root-expand-context/outer-post-expansion the-struct_0)"
 "(root-expand-context/outer-use-site-scopes the-struct_0)"
 "(root-expand-context/outer-frame-id the-struct_0)"
@@ -38482,10 +38477,13 @@ static const char *startup_source =
 "(promise1.1"
 "(lambda()"
 "(let-values(((ns-151_0)"
-" ns-1_0))"
+" ns-1_0)"
+"((temp52_0)"
+" #t))"
 "(make-expand-context.1"
 " #f"
 " #f"
+" temp52_0"
 " #f"
 " #f"
 " ns-151_0)))"
@@ -38594,20 +38592,20 @@ static const char *startup_source =
 "(void))"
 "(values))))"
 "(let-values(((inst_0)"
-"(let-values(((ns53_0) ns_0)"
-"((phase-shift54_0) phase-shift_0)"
-"((self55_0) self_0)"
-"((insp56_0) insp_0)"
-"((bulk-binding-registry57_0) bulk-binding-registry_0)"
-"((temp58_0)"
+"(let-values(((ns54_0) ns_0)"
+"((phase-shift55_0) phase-shift_0)"
+"((self56_0) self_0)"
+"((insp57_0) insp_0)"
+"((bulk-binding-registry58_0) bulk-binding-registry_0)"
+"((temp59_0)"
 "                                    (lambda (name_0 val_0) (error \"shouldn't get here for the root-ctx linklet\"))))"
 "(make-instance-instance.1"
-" bulk-binding-registry57_0"
-" insp56_0"
-" ns53_0"
-" phase-shift54_0"
-" self55_0"
-" temp58_0))))"
+" bulk-binding-registry58_0"
+" insp57_0"
+" ns54_0"
+" phase-shift55_0"
+" self56_0"
+" temp59_0))))"
 "(let-values(((syntax-literals-instance_0)"
 "(if syntax-literals-linklet_0"
 "(1/instantiate-linklet"
@@ -38627,8 +38625,8 @@ static const char *startup_source =
 "(promise1.1"
 "(lambda()"
 "(shift-to-inside-root-context"
-"(let-values(((self59_0) self_0))"
-"(make-root-expand-context.1 #f null unsafe-undefined unsafe-undefined self59_0))))"
+"(let-values(((self60_0) self_0))"
+"(make-root-expand-context.1 #f null unsafe-undefined unsafe-undefined self60_0))))"
 " #f)))"
 "(if(procedure? get-encoded-root-expand-ctx_0)"
 "(let-values()"
@@ -42016,6 +42014,7 @@ static const char *startup_source =
 " #f"
 " #f"
 " #f"
+" #f"
 " ns-140_0))"
 "(let-values()"
 "(instantiate_0"
@@ -44268,6 +44267,8 @@ static const char *startup_source =
 "(expand-context/inner-normalize-locals?"
 " the-struct_1)"
 "(expand-context/inner-should-not-encounter-macros?"
+" the-struct_1)"
+"(expand-context/inner-skip-visit-available?"
 " the-struct_1)))"
 "(raise-argument-error"
 " 'struct-copy"
@@ -44469,7 +44470,8 @@ static const char *startup_source =
 "(expand-context/inner-for-serializable? the-struct_1)"
 "(expand-context/inner-to-correlated-linklet? the-struct_1)"
 "(expand-context/inner-normalize-locals? the-struct_1)"
-"(expand-context/inner-should-not-encounter-macros? the-struct_1)))"
+"(expand-context/inner-should-not-encounter-macros? the-struct_1)"
+"(expand-context/inner-skip-visit-available? the-struct_1)))"
 "                                            (raise-argument-error 'struct-copy \"expand-context/inner?\" the-struct_1)))))"
 "(expand-context/outer1.1"
 " inner220_0"
@@ -45954,7 +45956,8 @@ static const char *startup_source =
 "(expand-context/inner-to-correlated-linklet? the-struct_1)"
 "(expand-context/inner-normalize-locals? the-struct_1)"
 "(expand-context/inner-should-not-encounter-macros?"
-" the-struct_1)))"
+" the-struct_1)"
+"(expand-context/inner-skip-visit-available? the-struct_1)))"
 "(raise-argument-error"
 " 'struct-copy"
 "                                                       \"expand-context/inner?\""
@@ -49669,6 +49672,7 @@ static const char *startup_source =
 "(make-expand-context.1"
 " serializable?110_0"
 " observer112_0"
+" #f"
 " to-correlated-linklet?111_0"
 " to-parsed?109_0"
 " ns108_0))))"
@@ -49765,7 +49769,8 @@ static const char *startup_source =
 "(let-values(((require-lifts_0 lifts_0 exp-s_0)"
 "(expand-capturing-lifts"
 " s_0"
-"(let-values(((v_0)(let-values(((ns138_0) ns_0))(make-expand-context.1 #f #f #f #f ns138_0))))"
+"(let-values(((v_0)"
+"(let-values(((ns138_0) ns_0))(make-expand-context.1 #f #f #f #f #f ns138_0))))"
 "(let-values(((the-struct_0) v_0))"
 "(if(expand-context/outer? the-struct_0)"
 "(let-values(((inner139_0)"
@@ -49800,7 +49805,8 @@ static const char *startup_source =
 "(expand-context/inner-for-serializable? the-struct_1)"
 "(expand-context/inner-to-correlated-linklet? the-struct_1)"
 "(expand-context/inner-normalize-locals? the-struct_1)"
-"(expand-context/inner-should-not-encounter-macros? the-struct_1)))"
+"(expand-context/inner-should-not-encounter-macros? the-struct_1)"
+"(expand-context/inner-skip-visit-available? the-struct_1)))"
 "(raise-argument-error"
 " 'struct-copy"
 "                                              \"expand-context/inner?\""
@@ -49892,7 +49898,7 @@ static const char *startup_source =
 "(let-values(((s_0)(maybe-intro given-s_0 ns_0)))"
 "(let-values(((ctx_0)"
 "(let-values(((ns149_0) ns_0)((observer150_0) observer_0))"
-"(make-expand-context.1 #f observer150_0 #f #f ns149_0))))"
+"(make-expand-context.1 #f observer150_0 #f #f #f ns149_0))))"
 "(let-values(((phase_0)(namespace-phase ns_0)))"
 "((letrec-values(((loop_0)"
 "(lambda(s_1 phase_1 ns_1 as-tail?_0)"
@@ -49968,6 +49974,8 @@ static const char *startup_source =
 "(expand-context/inner-normalize-locals?"
 " the-struct_1)"
 "(expand-context/inner-should-not-encounter-macros?"
+" the-struct_1)"
+"(expand-context/inner-skip-visit-available?"
 " the-struct_1)))"
 "(raise-argument-error"
 " 'struct-copy"
@@ -50090,6 +50098,8 @@ static const char *startup_source =
 "(expand-context/inner-normalize-locals?"
 " the-struct_1)"
 "(expand-context/inner-should-not-encounter-macros?"
+" the-struct_1)"
+"(expand-context/inner-skip-visit-available?"
 " the-struct_1)))"
 "(raise-argument-error"
 " 'struct-copy"
@@ -50622,6 +50632,8 @@ static const char *startup_source =
 "(expand-context/inner-normalize-locals?"
 " the-struct_1)"
 "(expand-context/inner-should-not-encounter-macros?"
+" the-struct_1)"
+"(expand-context/inner-skip-visit-available?"
 " the-struct_1)))"
 "(raise-argument-error"
 " 'struct-copy"
@@ -63380,9 +63392,12 @@ static const char *startup_source =
 " current-expand-context"
 " #f"
 "(let-values()"
+"(if(expand-context-skip-visit-available? ctx_0)"
+"(void)"
+"(let-values()"
 "(namespace-visit-available-modules!"
 "(expand-context-namespace ctx_0)"
-" phase_0)))"
+" phase_0)))))"
 "(values))))"
 "(let-values((()"
 "(begin"
@@ -75477,6 +75492,8 @@ static const char *startup_source =
 "(expand-context/inner-normalize-locals?"
 " the-struct_1)"
 "(expand-context/inner-should-not-encounter-macros?"
+" the-struct_1)"
+"(expand-context/inner-skip-visit-available?"
 " the-struct_1)))"
 "(raise-argument-error"
 " 'struct-copy"
@@ -76523,7 +76540,8 @@ static const char *startup_source =
 "(expand-context/inner-for-serializable? the-struct_1)"
 "(expand-context/inner-to-correlated-linklet? the-struct_1)"
 "(expand-context/inner-normalize-locals? the-struct_1)"
-"(expand-context/inner-should-not-encounter-macros? the-struct_1)))"
+"(expand-context/inner-should-not-encounter-macros? the-struct_1)"
+"(expand-context/inner-skip-visit-available? the-struct_1)))"
 "                                (raise-argument-error 'struct-copy \"expand-context/inner?\" the-struct_1)))))"
 "(expand-context/outer1.1"
 " inner198_0"
@@ -76891,6 +76909,8 @@ static const char *startup_source =
 "(expand-context/inner-normalize-locals?"
 " the-struct_1)"
 "(expand-context/inner-should-not-encounter-macros?"
+" the-struct_1)"
+"(expand-context/inner-skip-visit-available?"
 " the-struct_1)))"
 "(raise-argument-error"
 " 'struct-copy"
@@ -77323,6 +77343,8 @@ static const char *startup_source =
 "(expand-context/inner-normalize-locals?"
 " the-struct_1)"
 "(expand-context/inner-should-not-encounter-macros?"
+" the-struct_1)"
+"(expand-context/inner-skip-visit-available?"
 " the-struct_1)))"
 "(raise-argument-error"
 " 'struct-copy"
@@ -77592,6 +77614,8 @@ static const char *startup_source =
 "(expand-context/inner-normalize-locals?"
 " the-struct_1)"
 "(expand-context/inner-should-not-encounter-macros?"
+" the-struct_1)"
+"(expand-context/inner-skip-visit-available?"
 " the-struct_1)))"
 "(raise-argument-error"
 " 'struct-copy"
@@ -77780,6 +77804,8 @@ static const char *startup_source =
 "(expand-context/inner-normalize-locals?"
 " the-struct_1)"
 "(expand-context/inner-should-not-encounter-macros?"
+" the-struct_1)"
+"(expand-context/inner-skip-visit-available?"
 " the-struct_1)))"
 "(raise-argument-error"
 " 'struct-copy"
@@ -78025,6 +78051,8 @@ static const char *startup_source =
 "(expand-context/inner-normalize-locals?"
 " the-struct_1)"
 "(expand-context/inner-should-not-encounter-macros?"
+" the-struct_1)"
+"(expand-context/inner-skip-visit-available?"
 " the-struct_1)))"
 "(raise-argument-error"
 " 'struct-copy"
@@ -78252,6 +78280,8 @@ static const char *startup_source =
 "(expand-context/inner-normalize-locals?"
 " the-struct_1)"
 "(expand-context/inner-should-not-encounter-macros?"
+" the-struct_1)"
+"(expand-context/inner-skip-visit-available?"
 " the-struct_1)))"
 "(raise-argument-error"
 " 'struct-copy"
@@ -80045,6 +80075,8 @@ static const char *startup_source =
 "(expand-context/inner-normalize-locals?"
 " the-struct_1)"
 "(expand-context/inner-should-not-encounter-macros?"
+" the-struct_1)"
+"(expand-context/inner-skip-visit-available?"
 " the-struct_1)))"
 "(raise-argument-error"
 " 'struct-copy"
@@ -81590,6 +81622,8 @@ static const char *startup_source =
 "(expand-context/inner-normalize-locals?"
 " the-struct_1)"
 "(expand-context/inner-should-not-encounter-macros?"
+" the-struct_1)"
+"(expand-context/inner-skip-visit-available?"
 " the-struct_1)))"
 "(raise-argument-error"
 " 'struct-copy"
@@ -82647,6 +82681,8 @@ static const char *startup_source =
 "(expand-context/inner-normalize-locals?"
 " the-struct_1)"
 "(expand-context/inner-should-not-encounter-macros?"
+" the-struct_1)"
+"(expand-context/inner-skip-visit-available?"
 " the-struct_1)))"
 "(raise-argument-error"
 " 'struct-copy"
@@ -83520,7 +83556,8 @@ static const char *startup_source =
 "(expand-context/inner-to-correlated-linklet? the-struct_1)"
 "(expand-context/inner-normalize-locals? the-struct_1)"
 "(expand-context/inner-should-not-encounter-macros?"
-" the-struct_1)))"
+" the-struct_1)"
+"(expand-context/inner-skip-visit-available? the-struct_1)))"
 "(raise-argument-error"
 " 'struct-copy"
 "                                                        \"expand-context/inner?\""