Possible repeat{} / break function bug in R 3.4.1

oops, I should have tried it:

     expr <- quote(break)
     repeat(eval(expr))


So eval() has hybrid semantics where `break` has more reach than
return(), weird.

     expr <- quote(return())
     repeat(eval(expr))  # infloop

Lionel

On 23 ao?t 2017, at 09:24, Tomas Kalibera <tomas.kalibera at gmail.com> wrote:

It is a bug in the byte-code compiler. I will fix
Tomas

On 08/23/2017 09:22 AM, Lionel Henry wrote:

I don't think that's a bug. source() uses eval(), and eval() creates a
new function-like context frame. In a way expecting `break` to work
inside source() is like expecting `break` to cross stack frames:

     my_break <- function() break
     repeat(my_break())

Lionel

On 23 ao?t 2017, at 09:17, Martin Maechler <maechler at stat.math.ethz.ch> wrote:

Martin Maechler <maechler at stat.math.ethz.ch>
    on Wed, 23 Aug 2017 09:10:20 +0200 writes:
Peter Bosa <Peter.Bosa at oregonmetro.gov>
    on Tue, 22 Aug 2017 14:39:50 +0000 writes:

Hello, I've noticed the following error using repeat{} / break in R 3.4.1 running on Windows 10 and Windows Server 2008 (both 64-bit environments).
When running a repeat function, the break command causes an error message if the repeat command refers to code within a file, but does not produce an error if the code is contained within the repeat{} command.
Hello, I've noticed the following error using repeat{} / break in R 3.4.1 running on Windows 10 and Windows Server 2008 (both 64-bit environments).

When running a repeat function, the break command causes an error message if the repeat command refers to code within a file, but does not produce an error if the code is contained within the repeat{} command.

For example, the following code runs fine:

x <- 1
y <- 5

repeat {
if(x < y) {
print("No Break Dance :-(")
x = x + 1
} else {
print("Break Dance!")
break
}
}

[1] "No Break Dance :("
[1] "No Break Dance :("
[1] "No Break Dance :("
[1] "No Break Dance :("
[1] "No Break Dance :("
[1] "Break Dance!"
However, if I take the loop contents of the repeat{} function, and save them to a file (breakTest.R) that contains the following:

if(x < y) {
print("No Break Dance :-(")
x = x + 1
} else {
print("Break Dance!")
break
}

And then run the following code:

x <- 1
y <- 5

repeat{
source("./breakTest.R")
}

I get the following error:

[1] "No Break Dance :("
[1] "No Break Dance :("
[1] "No Break Dance :("
[1] "No Break Dance :("
[1] "No Break Dance :("
[1] "Break Dance!"
Error in eval(ei, envir) : no loop for break/next, jumping to top level
This was not an issue with previous versions of R that I have used, including 3.3.3.

Any suggestions? Is this a known bug with 3.4.1?

Thank you, Peter!
I can confirm what you are seeing (on Linux) in R version 3.4.0,
3.4.1, and "R devel", and also that this had worked w/o a
problem in earlier versions of R, where I've looked at
R version 3.3.3 and 3.2.5.
I do think this is a bug, but it was not known till now.
For ease of use, I attach the two R files to easily reproduce.
Note I use  writeLines() instead of print() as its output is "nicer".
Best regards,
Martin Maechler, ETH Zurich

Trying again with the two attachment.  Yes, I of all people (!!)
should know that they must have an allowed MIME type; in this
case  text/plain !

Martin

## see ./break-source_R341.R
if(x < y) {
  writeLines("No Break Dance :-(")
  x <- x + 1
} else {
  writeLines("Break Dance!")
  break
}
## From: Peter Bosa <Peter.Bosa at oregonmetro.gov>
## To: "R-devel at r-project.org" <R-devel at r-project.org>
## Subject: [Rd] Possible repeat{} / break function bug in R 3.4.1
## Date: Tue, 22 Aug 2017 14:39:50 +0000

## Hello, I've noticed the following error using repeat{} / break in R 3.4.1 running on Windows 10 and Windows Server 2008 (both 64-bit environments).

## When running a repeat function, the break command causes an error message if the repeat command refers to code within a file, but does not produce an error if the code is contained within the repeat{} command.

## For example, the following code runs fine:

x <- 1
y <- 5
repeat {
  if(x < y) {
    writeLines("No Break Dance :-(")
    x <- x + 1
  } else {
    writeLines("Break Dance!")
    break
  }
}
## No Break Dance :(
## No Break Dance :(
## No Break Dance :(
## No Break Dance :(
## No Break Dance :(
## Break Dance!
## >

## However, if I take the loop contents of the repeat{} function, and save
## them to a file (breakTest.R) that contains the following:
##                 ^^^^^^^^^^^
##                __SEE THAT FILE__
## if(x < y) {
##   writeLines("No Break Dance :-(")
##   x = x + 1
## } else {
##   writeLines("Break Dance!")
##   break
## }

## And then run the following code:

x <- 1
y <- 5
repeat{
  source("./breakTest.R")
}
cat("successfully finished\n")

## I get the following error:

## No Break Dance :(
## No Break Dance :(
## No Break Dance :(
## No Break Dance :(
## No Break Dance :(
## Break Dance!
## Error in eval(ei, envir) : no loop for break/next, jumping to top level
## ^^^^^^^^^^^^^^^^^^^^


## This was not an issue with previous versions of R that I have used, including 3.3.3.

## MM: It does work in R 3.3.3, indeed
## --  it fails in R 3.4.0 and later


## Any suggestions? Is this a known bug with 3.4.1?

## Cheers-
## Peter


## ----------------------------------------------------------------
## peter bosa
## metro
## modeling services
## 600 ne grand ave
## portland, or  97232

## peter.bosa at oregonmetro.gov<mailto:peter.bosa at oregonmetro.gov>
## 503.797.1771

## metro | making a great place
## www.oregonmetro.gov