Compiler issue: unexpected error when compiling an abstract generic method

[xloggr]

F# compiler generates an unexpected error when building code containing an abstract generic method declaration. Similar non-generic code compiles with no errors.

Here's an example:

Non-generic version - compiles with no errors:

type IMyInterface =
  abstract member Sort: int list -> int list

Generic version

type IMyInterface =
  abstract member Sort<'T>: 'T list -> 'T list

fails to compile producing the following (somewhat cryptic) errors:

[FS0035] This construct is deprecated: ':' is not permitted as a character in operator names and is reserved for future use
[FS0010] Unexpected quote symbol in member definition. Expected ':' or other token.
[FS0010] Unexpected keyword 'type' in implementation file

To make the code compile I had to add a space before the colon:

type IMyInterface() =
  abstract member Sort<'T> : 'T list -> 'T list
  //   note the space     ^

It's inconsistent with the non-generic version which compiles with or without a space before the colon.
Seems to be a grammar definition issue...

Related information

• OS: Ubuntu 24.04
• .NET: 8.0.11
• Editing Tools: JetBrains Rider

[edgarfgp]

I remember fixing this at some point in NET8. You can try SDK 8.0.404 to see if the fix made there.

[xloggr]

You're right, its fixed in 8.0.404 - thank you!

[edgarfgp]

Closing this as it was fixed by #15923