msgfmt produces invalid UTF-8 sequences for desktop files

[Mike WIlliams]

VIM has recently added support for validating gnome desktop files and this is reporting errors due to invalid UTF-8 sequences produced by msgfmt.

Steps to reproduce:
1. Checkout rev 1253704 from the VIM git repo on GitHub - https://github.com/vim/vim
2. Run ./configure in the repo to set up the build environment.
2. Change to the po directory in the repo - cd src/po
3. Process and validate the gvim desktop file using the Makefile -

$ make gvim.desktop
msgfmt --desktop -d . --template gvim.desktop.in -o tmp_gvim.desktop
rm -f LINGUAS
if command -v desktop-file-validate; then desktop-file-validate tmp_gvim.desktop; fi
/usr/bin/desktop-file-validate
tmp_gvim.desktop: warning: file contains lines that are not UTF-8 encoded. There is no guarantee the validator will correctly work.
[Invalid UTF-8] tmp_gvim.desktop: error: value "\xe0\xac\xaa\xe0\xac\xbe\xe0\xac\xa0\xe0\xad\x8d\xe0\xac\xaf \xe0\xac\xab\xe0\xac\xbe\xe0\xac\x87\xe0\xac\xb2\xe0\xac\x97\xe0\xad\x81\xe0\xac\xa1\xe0\xac\xbc\xe0\xac\xbf\xe0\xac\x95\xe0\xad\x81 \xe0\xac\xb8\xe0\xac\xae\xe0\xad\x8d\xe0\xac\xaa\xe0\xac\xbe\xe0\xac\xa6\xe0\xac\xa8 \xe0\xac\x95\xe0\xac\xb0\xe0\xac\xa8\xe0\xad\x8d\xe0\xac\xa4\xe0\xad" for locale string key "Comment[or]" in group "Desktop Entry" contains invalid UTF-8 characters, locale string values should be encoded in UTF-8
Makefile:176: recipe for target 'gvim.desktop' failed
make: *** [gvim.desktop] Error 1

The template file has valid UTF-8 sequences so no errors are expected. The error is correct as the generated desktop file has a truncated 3 byte UTF-8 sequence at the end of the line as reported. The problem is msgfmt is emitting an invalid UTF-8 sequence for this one line.

This is happening on an up to date 16.04 LTS -

$ apt list gettext desktop-file-utils
Listing... Done
desktop-file-utils/xenial-updates,now 0.22-1ubuntu5.2 i386 [installed]
gettext/xenial-updates,xenial-security,now 0.19.7-2ubuntu3.1 i386 [installed]

There has been some discussion of this issue on the VIM developers mailing list - https://groups.google.com/d/msg/vim_dev/yYGCsJJPlA0/i1PNO_46AgAJ

A candidate patch for the issue from upstream for the gettext package has been identified -
https://groups.google.com/d/msg/vim_dev/yYGCsJJPlA0/6yAEzO9LAgAJ

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: gettext 0.19.7-2ubuntu3.1
ProcVersionSignature: Ubuntu 4.15.0-51.55~16.04.1-generic 4.15.18
Uname: Linux 4.15.0-51-generic i686
ApportVersion: 2.20.1-0ubuntu2.18
Architecture: i386
CurrentDesktop: Unity
Date: Fri Jun 7 10:30:31 2019
InstallationDate: Installed on 2019-02-05 (121 days ago)
InstallationMedia: Ubuntu 16.04.5 LTS "Xenial Xerus" - Release i386 (20180731)
SourcePackage: gettext
UpgradeStatus: No upgrade log present (probably fresh install)

[Olivier Tilloy (osomon)]

I can reproduce the error in a xenial VM, not in a bionic one.