Modular•14mo ago

Should the language server warn about this case?

Consider the following code:

fn f() -> Int:
  <body>

fn f() -> Int:
  <body>

Mojo language server doesn't produce a type error when body doesn't contain a return. There are cases where this makes sense, like when <body> contains only pass or .... However, for the majority of cases, this clearly won't type check. So, I'm not sure if it's a bug or intended behaviour. FYI, Python language server like pyright produces the following error message:

def f() -> int:
#          ^^^ Function with declared return type "int" must return value on all code paths
  a = 1

def f() -> int:
#          ^^^ Function with declared return type "int" must return value on all code paths
  a = 1

9 Replies

Jack Clayton•14mo ago

Thanks yeah that's should work in the LSP, as it does produce a compiler error:

/tmp/main.mojo:5:1: error: return expected at end of function with results
fn timer() -> Int:
^

/tmp/main.mojo:5:1: error: return expected at end of function with results
fn timer() -> Int:
^

Would you mind raising an issue for it?

soraOP•14mo ago

Didn't sleep last night. Will raise an issue when I wake up. Filed here: https://github.com/modularml/mojo/issues/1159

ModularBot•14mo ago

Congrats @sora, you just advanced to level 5!

Jack Clayton•14mo ago

Thanks heaps @sora just seen it 🙏

gabrieldemarmiesse•14mo ago

I'm interested in this subject, I encountered a few weird things with the LSP, where the compiler produced an error but not the LSP. Should we always raise an issue on github when that happens? If I reformulate, is the expected behavior of the LSP to raise the same error messages as the compiler?

soraOP•14mo ago

I can imagine that there maybe cases where only the compiler can produce an error, maybe the compiler run more pass than the LSP.

gabrieldemarmiesse•14mo ago

Exactly @sora that's what I had in mind

soraOP•14mo ago

Maybe you could share the things you encountered and we can ask @Jack Clayton about it.

gabrieldemarmiesse•14mo ago

so yeah clarification would be appreciated

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Programming

Should the language server warn about this case?