0005697: better location info for type errors and/or warnings in sequences & let expressions

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0005697

OCaml

OCaml typing

public

2012-07-24 10:08

2012-07-24 11:45

Reporter

Drakken

Assigned To

frisch

Priority

low

Severity

tweak

Reproducibility

always

Status

resolved

Resolution

fixed

Platform

OS Version

Product Version

3.12.1

Target Version

Fixed in Version

Summary

0005697: better location info for type errors and/or warnings in sequences & let expressions

Description

The type checker currently reports the location of the entire body of a for loop when the body is mistyped, even though the mistake can be located more precisely for sequences and let expressions.
The included file fizzbuzz.ml has a for loop whose body contains a double let binding and a four-part sequence.
The mistake is in the last part of the sequence, where the call to print_newline is missing its unit argument. (oops! :)
The location of the current type warning unnecessarily contains all six lines
of the body, including both the let bindings and the entire sequence.

Steps To Reproduce

Compile fizzbuzz.ml and examine the location info
in the warning message:

$ ocamlc fizzbuzz.ml
File "fizzbuzz.ml", line 5, characters 2-176:
Warning 5: this function application is partial,
maybe some arguments are missing.

Additional Information

Patch is in included file typecore.ml.diff.

Improved output refers to only the faulty subexpression:

$ ocamlc fizzbuzz.ml
File "fizzbuzz.ml", line 10, characters 2-15:
Warning 5: this function application is partial,
maybe some arguments are missing.

Notes:
* The function type_approx does something similar.
* type_exp and other functions might also benefit from this.
* I have no idea whether the function final_subexpression
belongs somewhere else.
* Feel free to change the name "final_subexpression" if
you don't like it.

Tags

No tags attached.

Attached Files

typecore.ml.diff [^] (300 bytes) 2012-07-24 10:08 [Show Content] [Hide Content]

1024a1025,1030
> let rec final_subexpression sexp =
>   match sexp.pexp_desc with
>     Pexp_let (_, _, e) -> final_subexpression e
>   | Pexp_sequence (_,e) -> final_subexpression e
>   | _ -> sexp
> 
2121c2127
<   let loc = sexp.pexp_loc in
---
>   let loc = (final_subexpression sexp).pexp_loc in

fizzbuzz.ml [^] (266 bytes) 2012-07-24 10:26

Relationships

Notes
(0007799) frisch (developer) 2012-07-24 10:58 edited on: 2012-07-24 11:44	Thanks! Committed to trunk (rev 12763), also treating other cases (if, try, match).

(0007800) Drakken (reporter) 2012-07-24 11:44	Thanks, frisch. What about 4.00?

(0007801) frisch (developer) 2012-07-24 11:45	4.00 is almost out. It's too late to add anything to it, except maybe fixes for serious bugs.

Issue History
Date Modified	Username	Field	Change
2012-07-24 10:08	Drakken	New Issue
2012-07-24 10:08	Drakken	File Added: typecore.ml.diff
2012-07-24 10:26	Drakken	File Added: fizzbuzz.ml
2012-07-24 10:50	frisch	Assigned To	=> frisch
2012-07-24 10:50	frisch	Status	new => assigned
2012-07-24 10:58	frisch	Note Added: 0007799
2012-07-24 10:58	frisch	Status	assigned => resolved
2012-07-24 10:58	frisch	Resolution	open => fixed
2012-07-24 11:44	Drakken	Note Added: 0007800
2012-07-24 11:44	frisch	Note Edited: 0007799	View Revisions
2012-07-24 11:45	frisch	Note Added: 0007801