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Dependency conflicts

This page explains how to use the force_version keyword to handle dependency conflicts.

When

Conflicts occur when a voyager package requires a different version of an already included package. For example: Exceptions requires fmt 6.2 and BitFields requires fmt 6.0. To reproduce this you can use the following json: 

[{
  "repo": "example-generic-local",
  "library": "Utils/Exceptions",
  "version": "1.2"
},
{
  "repo": "example-generic-local",
  "library": "Utils/BitFields",
  "version": "1.1"
}]
Which will result in the following error: 
+-- Downloading Utils/Exceptions @ 1.2 ... MSVC.142.DBG.32 @ 1.2.0 OK
|   +- Downloading ThirdParty/fmt @ 6.2 ... MSVC.142.DBG.32 @ 6.2.0 OK
+-- Downloading Utils/BitFields @ 1.1 ... Header @ 1.1.0 OK
|   +- Downloading ThirdParty/fmt @ 6.0 ... ERROR: Version conflict within project for ThirdParty/fmt: 6.2.0 vs 6.0.0

How to resolve

force_version can be used to force the usage of a specific version of a package. To resolve conflicts in the above example change the voyager.json to this: 

[{
  "repo": "example-generic-local",
  "library": "ThirdParty/fmt",
  "version": "6.2",
  "force_version": true
},
{
  "repo": "example-generic-local",
  "library": "Utils/Exceptions",
  "version": "1.2"
},
{
  "repo": "example-generic-local",
  "library": "Utils/BitFields",
  "version": "1.1"
}]
Now fmt will be downloaded first and the force_version flag is saved. All other packages that require fmt will now be forced to use fmt 6.2 
+-- Downloading ThirdParty/fmt @ 6.2 ... MSVC.142.DBG.32 @ 6.2.0 (Force Version) OK
+-- Downloading Utils/Exceptions @ 1.2 ... MSVC.142.DBG.32 @ 1.2.0 OK
|   +- Downloading ThirdParty/fmt @ 6.2 ... SKIP: package already included in project
+-- Downloading Utils/BitFields @ 1.1 ... Header @ 1.1.0 OK
|   +- Downloading ThirdParty/fmt @ 6.0 ... WARN: Forcing version 6.0.0 to 6.2.0 SKIP: package already included in project

Rules

  • You can only use force_version to force to a higher version. Otherwise an error is thrown: ERROR: Cannot force 6.2.0 to lower version 6.0.0
  • You can always use force_version on non semver versions like branch names
  • It is forbidden to have a force_version attribute in the voyager_package.json, it will be removed when voyager package is called
  • Using force version can lead to unexpected behavior regarding ABI compatibility
  • Libraries with force_version should be defined in the voyager.json before they're downloaded through a dependency