From 3f9da4af4669b2026138b04c549955f15edd79cd Mon Sep 17 00:00:00 2001
From: Matthew Flatt <mflatt@racket-lang.org>
Date: Fri, 22 Jun 2018 09:09:56 -0600
Subject: [PATCH] prefer closest binding name for procedures

In some cases, such as

 (define g (let ([f (lambda (x) x)]) f))

the inner name `f` could get replaced by the outer name `g`.
Prefer the inner name so that macros can use a `let` wrapper
to reliably name a procedure.

original commit: 9ae0f856b0f81610c6caea13a5bfdf3b135de5b0
---
 LOG          |  2 ++
 mats/misc.ms | 17 +++++++++++++++++
 s/cp0.ss     |  4 +++-
 3 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/LOG b/LOG
index a16538db4a..93419364dc 100644
--- a/LOG
+++ b/LOG
@@ -960,3 +960,5 @@
     schlib.c
 - Updated csug socket code to match that in examples folder
     csug/foreign.stex, examples/socket.ss
+- Adjust cp0 to not replace a procedure name from a let wrapper
+    cp0.ss, misc.ms
diff --git a/mats/misc.ms b/mats/misc.ms
index 20250b3332..9825c0abb4 100644
--- a/mats/misc.ms
+++ b/mats/misc.ms
@@ -4948,6 +4948,23 @@
     (procedure-arity-mask 17))
   )
 
+(mat procedure-name
+  (begin
+    (define (procedure-name f)
+      (((inspect/object f) 'code) 'name))
+    (define should-be-named-f (let ([f (lambda (x) x)]) f))
+    (define should-be-named-g (letrec ([g (lambda (x) x)]) g))
+    (define should-be-named-h (let ([f (let ([h (lambda (x) x)]) h)]) f))
+    (define should-be-named-i (letrec ([f (let ([i (lambda (x) x)]) i)]) f))
+    (define should-be-named-j (let ([f (letrec ([j (lambda (x) x)]) j)]) f))
+    #t)
+  (equal? (procedure-name procedure-name) "procedure-name")
+  (equal? (procedure-name should-be-named-f) "f")
+  (equal? (procedure-name should-be-named-g) "g")
+  (equal? (procedure-name should-be-named-h) "h")
+  (equal? (procedure-name should-be-named-i) "i")
+  (equal? (procedure-name should-be-named-j) "j"))
+
 (mat fasl-immutable
   (begin
     (define immutable-objs (list (vector->immutable-vector '#(1 2 3))
diff --git a/s/cp0.ss b/s/cp0.ss
index 9c3a761288..fc599722b4 100644
--- a/s/cp0.ss
+++ b/s/cp0.ss
@@ -4538,7 +4538,9 @@
          (let-values ([(e args) (lift-let e e*)])
            (cp0-call preinfo e (build-operands args env wd moi) ctxt env sc wd name moi)))]
       [(case-lambda ,preinfo ,cl* ...)
-       (when (symbol? name)
+       (when (and (symbol? name)
+                  ;; Avoid replacing a name from an optimized-away `let` pattern:
+                  (not (preinfo-lambda-name preinfo)))
          (preinfo-lambda-name-set! preinfo
            (let ([x ($symbol-name name)])
              (if (pair? x) (cdr x) x))))