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parsing/Location.prerr_warning is hard-coded to use Format.err_formatter #5271

vicuna opened this issue May 19, 2011 · 2 comments


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commented May 19, 2011

Original bug ID: 5271
Reporter: rrolles
Assigned to: @damiendoligez
Status: closed (set by @xavierleroy on 2016-12-07T10:47:16Z)
Resolution: fixed
Priority: normal
Severity: minor
Version: 3.12.0
Target version: 4.02.2+dev / +rc1
Fixed in version: 4.02.2+dev / +rc1
Category: ~DO NOT USE (was: OCaml general)

Bug description

I have embedded a REPL in a third-party application. Things that issue errors are properly printed as errors, i.e.:

Characters 28-31:
let f = function | 1 -> 0 | "x" -> 1;;
Error: This pattern matches values of type string but a pattern was expected which matches values of type int

However, things that issue warnings instead give general errors about bad I/O descriptors:

Characters -1--1:
let f = function | 1 -> 0 | 1 -> 1;;
Error: I/O error: Bad file descriptor

I tracked down the cause of this behavior to parsing/, in the function prerr_warning:

open Format
let prerr_warning loc w = print_warning loc err_formatter w;;

For my purposes, I was able to change err_formatter to std_formatter, and I obtain the proper compiler warnings in my toplevel. In general, it would be nice if the source was changed upstream somehow such that such warnings were redirected into the functions I had registered using Format.set_formatter_output_functions.


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commented Sep 26, 2014

Comment author: rrolles

I know this bug does not seem very sexy or important given its modest description. However, it not being fixed means that users of my program IDAOCaml (an OCaml REPL for a third-party application) have to modify OCaml and recompile it from scratch. If it was fixed, they could just use the binary distribution. Pretty please?


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commented Feb 26, 2015

Comment author: @damiendoligez

I fixed this in branch 4.02 (rev 15867). I think. I'll try to install IDAOCaml to check that the problem is really fixed.

@vicuna vicuna closed this Dec 7, 2016

@vicuna vicuna added this to the 4.02.2 milestone Mar 14, 2019

@vicuna vicuna added the bug label Mar 20, 2019

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