Type variable escapes its scope in type inference - Githubissues

smlnj / legacy

This project is the old version of Standard ML of New Jersey that continues to support older systems (e.g., 32-bit machines).

BSD 3-Clause "New" or "Revised" License

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Type variable escapes its scope in type inference #311

Open kcrary opened 5 months ago

kcrary commented 5 months ago

Version

110.99.1

Operating System

[ ] Any
[X] Linux
[ ] macOS
[X] Windows
[ ] Other Unix

OS Version

No response

Processor

[ ] Any
[ ] Arm (using Rosetta)
[ ] PowerPC
[ ] Sparc
[ ] x86 (32-bit)
[X] x86-64 (64-bit)
[ ] Other

System Component

Core system

Severity

Major

Description

A bug in type inference seems to allow type variables to escape their scope.

Transcript

fun foo x = let fun bar () = let exception Baz of 'b in Baz x end in () end; val foo = fn : 'b -> unit
foo (); stdIn:2.1-2.7 Error: operator and operand do not agree [UBOUND match] operator domain: 'b operand: unit in expression: foo ()

Expected Behavior

foo should produce a type error

Steps to Reproduce

as above

Additional Information

No response

Email address

crary@cs.cmu.edu