fix load_all in windows with UTF8 codes

[shrektan]

If the source file contains nonASCII chars, like Chinese Chars, devtools::load_all() would fail with error as below, but Build & Reload the package works fine.

I think it's due to not explicitly setting the encoding param in readLines of source_one, see https://github.com/hadley/devtools/blob/master/R/source.r#L21

The error message sample

Loading package_abc
Error in parse(text = lines, n = -1, srcfile = srcfile) :
  invalid multibyte character in parser at line 12
In addition: Warning messages:
1: In grepl("\n", lines, fixed = TRUE) :
  input string 12 is invalid in this locale
2: In grepl("\n", lines, fixed = TRUE) :
  input string 14 is invalid in this locale
3: In grepl("\n", lines, fixed = TRUE) :
  input string 15 is invalid in this locale

Notes

1. add encoding = "UTF-8" in readLines() to fix the reading from the file
2. convert the lines to native encoding, so the printing of the function displays correctly

[hansharhoff]

I believe this is closely related to issue #1312

[hadley]

Are you sure this line is necessary?

[shrektan]

I'm pretty sure this is necessary, because I just reproduced this to confirm.

1. Let's say we are working on a windows platform, whose native encoding is not utf-8,
2. If we have a function (e.g., futf8()) that contains nonASCII chars in some package ,
3. Without lines <- enc2native(lines), devtools::load_all() performs good and the function futf8() works well,
4. But, if you print(futf8), you will find mess in the console,
5. It will be solved by adding this line.

without the line

with this line

[shrektan]

@hadley Oh, just notice that the load_all() has been moved to https://github.com/r-pkgs/pkgload

However, I just added support for reading encoding from DESCRIPTION as well as a unit test.

[shrektan]

Close because related code has been moved to https://github.com/r-pkgs/pkgload