From 79d6b9bc18263ed6a150a0cb522aada8475aef6a Mon Sep 17 00:00:00 2001
From: Matthew Flatt <mflatt@racket-lang.org>
Date: Sat, 6 Jul 2019 05:59:14 -0600
Subject: [PATCH] json: preserve old behavior in terminating a number

The json parser has allowed "1x" as "1" and "1e-0x" as "1.0", so
keep that behavior for now.
---
 pkgs/racket-test/tests/json/json.rkt |  2 ++
 racket/collects/json/main.rkt        | 12 +++++-------
 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/pkgs/racket-test/tests/json/json.rkt b/pkgs/racket-test/tests/json/json.rkt
index 4194f953df..6b089e243b 100644
--- a/pkgs/racket-test/tests/json/json.rkt
+++ b/pkgs/racket-test/tests/json/json.rkt
@@ -95,6 +95,7 @@
 
 (define (parse-tests)
   (test (string->jsexpr @T{  0   }) =>  0
+        (string->jsexpr @T{  0x  }) =>  0 ; not clearly a good idea, but preserve old behavior
         (string->jsexpr @T{  1   }) =>  1
         (string->jsexpr @T{ -1   }) => -1 ; note: `+' is forbidden
         (string->jsexpr @T{ -12  }) => -12
@@ -109,6 +110,7 @@
         (string->jsexpr @T{-10.34e03}) => -10340.0
         (string->jsexpr @T{-10.34e+3}) => -10340.0
         (string->jsexpr @T{-10.34e+03}) => -10340.0
+        (string->jsexpr @T{-10.34e+0x}) => -10.340 ; preserve old behavior
         (string->jsexpr @T{-10.34e-3}) => -1.034e-2
         (string->jsexpr @T{-10.34e-03}) => -1.034e-2
         (string->jsexpr @T{-10.34e+31}) => -1.034e32
diff --git a/racket/collects/json/main.rkt b/racket/collects/json/main.rkt
index 2c2f0455e5..d542719033 100644
--- a/racket/collects/json/main.rkt
+++ b/racket/collects/json/main.rkt
@@ -398,7 +398,7 @@
       (define c (read-byte i))
       (cond
         [(digit-byte? c)
-         (read-exponent-rest n exp (to-number c))]
+         (read-exponent-rest n exp (to-number c) 1)]
         [(eqv? c (char->integer #\+))
          (read-exponent-more n mark #"+" exp 1)]
         [(eqv? c (char->integer #\-))
@@ -411,23 +411,21 @@
     (define (read-exponent-more n mark mark2 exp sgn)
       (define c (read-byte i))
       (cond
-        [(and (digit-byte? c) (zero? (to-number c)))
-         (read-exponent-more n mark mark2 exp sgn)]
         [(digit-byte? c)
-         (read-exponent-rest n exp (* sgn (to-number c)))]
+         (read-exponent-rest n exp (to-number c) sgn)]
         [else (bad-input (bytes-append (n->string n exp)
                                        (bytes mark)
                                        mark2
                                        (maybe-bytes c))
                          #:eof? (eof-object? c))]))
     ;; more digits:
-    (define (read-exponent-rest n exp exp2)
+    (define (read-exponent-rest n exp exp2 sgn)
       (define c (peek-byte i))
       (cond
         [(digit-byte? c)
          (read-byte i)
-         (read-exponent-rest n exp (+ (* 10 exp2) (to-number c)))]
-        [else (exact->inexact (* n (expt 10 (+ exp exp2))))]))
+         (read-exponent-rest n exp (+ (* 10 exp2) (to-number c)) sgn)]
+        [else (exact->inexact (* n (expt 10 (+ exp (* sgn exp2)))))]))
     (start))
   ;;
   (define (read-json [top? #f])