Error when starting ign-gazebo if LC_NUMERIC in set to a locale with comma as a decimal separator

[osrf-migration]

Original report (archived issue) by Silvio Traversaro (Bitbucket: traversaro).

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Prerequisites

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  • Checked the Q&A board for common solutions: http://answers.gazebosim.org
  • Checked that your issue isn't already filed.
  • Checked that there is not already an Ignition package that provides the described functionality: https://ignitionrobotics.org/libs

Description

Remake of https://osrf-migration.github.io/sdformat-gh-pages/#!/osrf/sdformat/issues/60/error-when-starting-gazebo-if-lc_numeric (#60) . : )

I recently tried to test the work in progress version of ign-gazebo, and on my system I got a locale-related error (similar to
https://osrf-migration.github.io/sdformat-gh-pages/#!/osrf/sdformat/issues/60/error-when-starting-gazebo-if-lc_numeric (#60) , ros/urdfdom#98
and ros/urdfdom#98).

Steps to Reproduce

Launch ign-gazebo with a locale in which the decimal separator is not .:

LC_NUMERIC=it_IT ign-gazebo

Expected behavior:
If launched with the C locale, ign-gazebo start correctly:

straversaro@iiticublap103:~/src/gazebo-superbuild/build-ign-gcc-8/install/bin$ LC_ALL="C" ./ign-gazebo --verbose 3
[Msg] Ignition Gazebo v0.1.0~pre1
[GUI] [Msg] Loading config [/home/straversaro/src/gazebo-superbuild/build-ign-gcc-8/install/share/ignition/gazebo0/gui/gui.config]
[GUI] [Msg] World [default] initialized with [default_physics] physics profile.
[GUI] [Msg] Loading plugin [Scene3D]
[GUI] [Msg] Added plugin [3D View] to main window
[GUI] [Msg] Loading plugin [WorldControl]
[GUI] [Msg] Added plugin [World control] to main window
[GUI] [Msg] Loading plugin [WorldStats]
[GUI] [Msg] Added plugin [World stats] to main window
[GUI] [Msg] Serving scene information on [/world/default/scene/info]
[GUI] [Msg] Serving scene graph on [/world/default/scene/graph]
[GUI] [Msg] Publishing pose messages on [/world/default/pose/info]
[GUI] [Msg] Loading plugin [ignition-rendering1-ogre]

Actual behavior:

straversaro@iiticublap103:~/src/gazebo-superbuild/build-ign-gcc-8/install/bin$ ./ign-gazebo --verbose 3
[Msg] Ignition Gazebo v0.1.0~pre1
[GUI] [Msg] Loading config [/home/straversaro/src/gazebo-superbuild/build-ign-gcc-8/install/share/ignition/gazebo0/gui/gui.config]
Error [Param.cc:395] Invalid argument. Unable to set value [.1 ] for key[near].
Exception [Param.cc:44] SDF ASSERTION                     
Invalid parameter
In function       : Param
Assert expression : this->ValueFromString(_default)
terminate called after throwing an instance of 'sdf::v8::AssertionInternalError'
Aborted (core dumped)

Reproduces how often:

Everytime.

Versions

Ubuntu 18.04
sdformat branch : gz11

Additional Information

Checking the backtrace, it seems that the call sequence is:
sdf::Element::AddValue --> sdf::Element::CreateParam --> sdf::Param::Param --> sdf::Param::ValueFromString

A related commit is https://osrf-migration.github.io/sdformat-gh-pages/#!/osrf/sdformat/commits/f6af03cf3a63d3a6dd1492a2f6031475625a71cd (3488a30) ,
but I am not sure why I never experienced this, as template<typename T> void Param::Init(const std::string &_value)
method was prone to this locale error as well.

A proper solution could be to substitute calls to str::stod with a locale-safe custom function as done in
https://github.com/ros/urdfdom_headers/pull/42/files . An alternative, for the branch of SDFormat that support C++17
would be to use std::from_chars. Unfortunately, not all the strings
that represent a valid XML floating point number are valid inputs to std::from_chars (for example, +1.0 is not a valid input to
std::to_chars), so even this is not a trivial solution.

[osrf-migration]

Original comment by Louise Poubel (Bitbucket: chapulina, GitHub: chapulina).

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See pull request #492

[osrf-migration]

Original comment by Silvio Traversaro (Bitbucket: traversaro).

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• changed state from "new" to "resolved"

Fixed with https://osrf-migration.github.io/sdformat-gh-pages/#!/osrf/sdformat/pull-requests/492/fix-locale-problems-of-std-stringstream/diff .