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2023.2
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  1. Project-level assistance
  2. Analyze and optimize project references

Analyze and optimize project references

Last modified: 23 May 2023

ReSharper | Find | Optimize References…

CtrlAlt0Y (ReSharper_OptimizeReferences)

This feature helps manage your existing project/assembly references, browse usages of the referenced projects/assemblies, and remove unused references. You can invoke this feature on any single project and use the Analyze References window to analyze and optimize project references.

tip

This feature does not require your project to be compiled, which means you can invoke it even if your project is currently broken.

Analyze project references

The Analyze References tool window displays project/assembly references in the current project, and let you explore how exactly the references are used. To explore usages of a specific assembly, namespace or type, you can filter them by kind and group them.

The symbol icons could help you distinguish between different kinds of symbols. Each usage is displayed with the line number and column; different icons mean different kinds of usages like read, write, attribute, or invocation usage. You can double-click any usage to navigate directly to the source code.

Remove unused references

The easiest way to clean up project references is to click Remove All Unused References Themed icon remove all unused references screen gray on the toolbar. If you want ro retain some unused references or remove some of the used references (and manually resolve the compilation errors that follow), you can make the corresponding selection and click Remove Selected References Themed icon remove selected reference screen gray.

tip

If your project references implicitly loaded assemblies, you can exclude them from cleanup before you start it

When you remove project and assembly references, ReSharper also deletes all redundant namespace import directives (using in C#, Imports in Visual Basic) that reference namespaces from the removed assemblies.

note

The operation of removing project/assembly references cannot be undone.

All Visual Studio projects must reference mscorlib and, starting from Visual Studio 2010, System.Core assemblies. These assemblies are marked with the pin Themed icon pin screen gray icon and you cannot remove these references.

References that are needed for compilation, independently of whether they are used or not, are displayed in the References required by the compiler group. References in this group are normally have 'related usages', that is, implicit (non-direct) usages. In the simplest case, related usages are caused by a type’s hierarchy. That is, if you use a certain type, you have to reference all assemblies containing that type’s supertypes.

NuGet packages are displayed with the corresponding icons Themed icon nu get screen gray. A faded icon means that the package has no usages and can be safely removed. When removing NuGet packages, ReSharper will use the NuGet uninstall mechanism.

There are other ways of cleaning project and assembly references.

  • You can invoke the Remove Unused References command on the project or on the References node in the Solution Explorer.

  • You can expand the References node in the Solution Explorer, select the references you want to remove and invoke the Safe Delete refactoring, which either silently removes unused references or opens a dialog showing how and where the selected references are used.

Retain references to implicitly loaded assemblies

Some project types use references implicitly, which means that these references are only used in runtime. These references cannot be safely removed even though there are no code dependencies on them.

If you still want to use ReSharper cleanup features (Remove All Unused References button in the Analyze References window and Remove Unused References refactoring), you need to mark the implicitly loaded assemblies as such.

Mark implicitly loaded assemblies

  1. Open the Analyze References window.

  2. In the Unused references section, find the implicitly used references you need to retain.

  3. Right-click the references and choose one of the following options:

    • Mark reference as used at runtime - to exclude the selected reference from cleanup in the current project

    • Mark reference as used at runtime for whole solution - to exclude the selected reference from cleanup in all projects in the solution

  4. ReSharper will save the information about implicitly used references in its layered settings — in a *.DotSettings.user file either for the project or solution.

Analyze References window

Control

Name

Description

Themed icon refresh screen gray

Refresh

Updates window content to reflect any changes made in the code or externally.

Themed icon expand all screen gray Themed icon collapse all screen gray

Expand All/Collapse All

Expands/collapses all nodes in the current tab.

Themed icon up screen gray Themed icon down screen gray

Previous/Next


Shift+F8 / F8

Navigate to the previous/next item and scrolls through the source code accordingly.

Themed icon preview toggle screen gray

Show Preview Ctrl+P

Hides or shows the pane with a preview of the selected item in the position specified using the list (at the bottom or in the right part of the window).

Themed icon export screen gray

Export

Click this button to export the data currently displayed in the window in text format , or use the drop-down selector to export the data in an XML or HTML format. The Export Data dialog that appears will help you save the data to a file or copy it to the clipboard .

Themed icon merge screen gray

Merge Occurrences on the Same Line

When this option is selected, occurrences on the same line are shown as a single item.

Themed icon remove all unused references screen gray

Remove All Unused References

Removes all assembly references that are not used.

Themed icon remove selected reference screen gray

Remove Selected References

Removes all selected assembly references.

Themed icon filter screen gray

Filter Usages

With this list, you can select specific kinds of usages to display - for example, declaration, invocation, parameter, method return, and so on. Click Show All Usages to enable all kinds of usages or Clear Filters to disable all kinds of usages thus hiding all usages in the current tab.

Group by

Allows grouping items in the window by different categories.

Window tabs

When results of the Optimize references command open in the window, they are displayed in new tabs, which show up on the left. The previously open tabs move to the right if the width of the window allows, otherwise they unload themselves saving memory - but you can always restore them by clicking the arrow that appears to the right of the tabs and clicking the required tab:

Tool window tabs

To prevent a tab from unloading, click the pin icon Themed icon pin screen gray next to the tab title.

See also

Concepts

Procedures