From a68c8eadc6fbcc901ef79342c07d80742e4c6ed7 Mon Sep 17 00:00:00 2001
From: Matthew Flatt <mflatt@racket-lang.org>
Date: Fri, 21 Feb 2020 21:26:18 -0700
Subject: [PATCH] cs: fix `hash{,eq,eqv}` on an odd number of arguments

Closes #3051
---
 pkgs/racket-test-core/tests/racket/basic.rktl | 10 ++++++++++
 racket/src/cs/rumble/hash.ss                  |  5 +++++
 2 files changed, 15 insertions(+)

diff --git a/pkgs/racket-test-core/tests/racket/basic.rktl b/pkgs/racket-test-core/tests/racket/basic.rktl
index 7246a4dc06..065c478ea4 100644
--- a/pkgs/racket-test-core/tests/racket/basic.rktl
+++ b/pkgs/racket-test-core/tests/racket/basic.rktl
@@ -394,6 +394,16 @@
 (test #t eq? (hasheq) (hash-remove (hasheq 3 4) 3))
 (test #t eq? (hasheqv) (hash-remove (hasheqv 3 4) 3))
 
+(err/rt-test (hash 1))
+(err/rt-test (hasheqv 1))
+(err/rt-test (hasheq 1))
+(err/rt-test (make-hash 1))
+(err/rt-test (make-hasheqv 1))
+(err/rt-test (make-hasheq 1))
+(err/rt-test (make-weak-hash 1))
+(err/rt-test (make-weak-hasheqv 1))
+(err/rt-test (make-weak-hasheq 1))
+
 (test #t symbol? 'foo)
 (test #t symbol? (car '(a b)))
 (test #f symbol? "bar")
diff --git a/racket/src/cs/rumble/hash.ss b/racket/src/cs/rumble/hash.ss
index 792ab136c2..3a0444c1d3 100644
--- a/racket/src/cs/rumble/hash.ss
+++ b/racket/src/cs/rumble/hash.ss
@@ -73,6 +73,11 @@
            (let loop ([kvs kvs] [h empty-hash])
              (cond
               [(null? kvs) h]
+              [(null? (cdr kvs))
+               (raise-arguments-error
+                'vararg-ctor
+                "key does not have a value (i.e., an odd number of arguments were provided)"
+                "key" (car kvs))]
               [else (loop (cddr kvs) (intmap-set h (car kvs) (cadr kvs)))]))]))
 
        (define list-ctor