Bug #21097: `x = a rescue b in c` and `def f = a rescue b in c` parsed differently between parse.y and prism

• Status: Open
• Assignee: prism
• Target version: -
• ruby -v: ruby 3.5.0dev (2025-01-27T08:19:32Z master c3c7300b89) +YJIT +MN +PRISM [arm64-darwin22]
• Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN

[tompng (tomoya ishida)]

x = a rescue b in c
(x = (a rescue b)) in c # parse.y, prism(ruby 3.4)
x = (a rescue (b in c)) # prism(ruby 3.5)

def f = a rescue b in c #=> true(parse.y), :f(prism)
(def f = (a rescue b)) in c # parse.y
def f = (a rescue (b in c)) # prism

There is no difference between prism and parse.y parsing these codes

a rescue b in c # a rescue (b in c)
x = a rescue b # x = (a rescue b)
x = b in c # (x = b) in c
def f = a rescue b # def f = (a rescue b)
def f = b in c # (def f = a) in b

[tompng (tomoya ishida)]

not in and not rescue has the same problem

$ ruby --parser=parse.y -e "def f = not 1 in 2; p f"
false
$ ruby --parser=prism   -e "def f = not 1 in 2; p f"
true
$ ruby --parser=parse.y -e "def f = not a rescue true; p f"
false
$ ruby --parser=prism   -e "def f = not a rescue true; p f"
true

[tenderlovemaking (Aaron Patterson)]

• Assignee set to prism