JetBrains Rider 2018.1 Help

Code Inspections

JetBrains Rider provides over 2300 code inspections in all supported languages. These inspections are used to detect and highlight code issues in design time in all opened files, and/or to find all code issues in specific scope, which can be as large as the entire solution.

Code inspections can be divided into the following groups:

  • Inspections with the fixed severity level 'Error'. These inspections detect compiler errors and there is no way to disable or configure them.
  • Inspections with configurable severity levels, which detect the rest of code issues (e.g. compiler warnings, runtime and logical errors, code smells, redundancies, improvement suggestions, etc.). You can find these configurable inspections on the Editor | Inspection Severity page of JetBrains Rider settings (Ctrl+Alt+S). These inspections can be configured in several ways — you can suppress the detected issues with comments and attributes, disable them or change their severity level in settings or .editorconfig files.

Severity levels of code inspections

Each JetBrains Rider code inspection has one of the following severity levels:

Error

Code inspections that have the 'Error' severity level by default are aimed at code issues that either prevent your code from compiling or result in runtime errors. Most of these inspections are not configurable, i.e. you cannot disable them or change their severity level.

In design-time inspection, JetBrains Rider displays unresolved symbols in red:

Code Analysis Code Highlighting Errors 1
and highlights erroneous statements or part of them with a red curly underline:
Code Analysis Code Highlighting Errors 2
If there is at least one error in the current file, the status indicator displays the Error ThemedIcon ErrorStripeError Screen Gray icon, and red markers are shown for each error on the marker bar.

Code issues that are found with inspections having the 'Error' severity level, appear in the Errors in Solution window if the solution-wide analysis is enabled.

Warning

This severity level corresponds to compiler warnings and to other issues that do not prevent your code from compiling but may nevertheless represent serious coding inefficiencies. For example, JetBrains Rider informs you about redundant type casts or namespace import directives, incorrect format strings, declared but never used local variables or private fields, unused private methods, etc.

In design-time inspection, JetBrains Rider displays redundant symbols with greyed text:

Code Analysis Code Highlighting Warnings 1
and highlights statements or part of them with a blue curly underline:
Code Analysis Code Highlighting Warnings 2
If there is at least one warning in the current file, the status indicator displays the Warning ThemedIcon ErrorStripeWarning Screen Gray icon, and yellow markers are shown for each warning on the marker bar.

Warnings also appear in the Errors in Solution window if the solution-wide analysis with warnings is enabled

Suggestion

Code issues with this severity level provide insights into code structure, drawing your attention to things that aren't necessarily bad or wrong, but probably useful to know.

For instance, you might be interested to know that 'parameter can be declared with base type', meaning that your method only uses members of the parameter's base type. This can be an indication of a different error, such as failure to take into account the specifics of the actual parameter type. Based on this knowledge, you may want to change the parameter's type - or not, if that is by design.

In design-time inspection, JetBrains Rider highlights suggestions with a green curly underline:

Code Analysis Code Highlighting Suggestions 1
and adds green markers for each warning on the marker bar.

Hint

This is the lowest severity level. Code issues with this severity simply bring your attention to a particular code detail and/or recommends a way of improvement.

In design-time inspection, JetBrains Rider highlights hints by adding a dashed green underline to the initial two letters of the corresponding symbol:

Code Analysis Code Highlighting Hints 1
Unlike errors, warnings and suggestions, hints are not taken into account when you navigate between code issues in the editor, and not shown in the marker bar.

Note that when you set the caret over a highlighted hint, no pop-up is shown, the corresponding message only appears in the status bar.

Severity levels of most code inspections (except those detecting compiler errors) can be changed, i.e. you can define severity levels for each code inspection according to your needs.

When you inspect code in specific scope, JetBrains Rider adds corresponding icons to the detected issues and allows sorting issues by the severity level in the Inspection Results window.

Categories of code inspections

JetBrains Rider groups configurable code inspections by several categories. These categories roughly define purposes of inspections and kinds of code issues that they detect. The categories are used to group code inspections on the Editor | Inspection Severity page of JetBrains Rider settings (Ctrl+Alt+S), and to group code issues found in specific scope and displayed in the Inspection Results window.

  • Potential Code Quality Issues
    This category includes inspections that detect critical issues (code smells), mostly with Error or Warning level. This category also includes inspections that ensure localization assistance.
  • Common Practices and Code Improvements
    This category groups inspections that hunt for medium severity issues that mainly affect code readability.
  • Redundancies in Code
    Code inspections in this category look for redundancies and dead code, which affect code readability and style, and could be safely removed. Some code redundancies cannot be fixed automatically, and quick-fixes for them are performed in the interactive mode, requiring the user input. But the majority of the redundancies can be fixed without user interaction, using either fix in scope or code cleanup.
  • Language Usage Opportunities
    This category includes code inspections, mostly with the suggestion severity level, which notify you when more advanced language constructs can be used. These inspections detect syntax of outdated language versions and suggest using features from more modern language versions. For most of the supported languages, language version can be detected automatically or set manually.
  • Code Notifications
    This category groups code inspections with minor severity levels.
  • Code Style
    Inspections in this category detect violations of code syntax styles. In contrast to most of other code inspections, these inspections can either detect the same code construct as a code issue or not depending on the corresponding code style rule configured on the Editor | Code Style | [Language] | Code Style page of JetBrains Rider settings (Ctrl+Alt+S). You can also fix issues that these inspection detect, using code cleanup.
  • Constraints Violations
    This category includes code inspections, mostly with the warning severity level, which detect violations related to symbol attributes, including JetBrains Rider's code annotations, and other similar issues.
  • Redundancies in Symbol Declaration
    This category includes code inspections, mostly with the warning severity level, which detect empty and unused symbol declarations.
  • Compiler Warnings
    Inspections in this category detect compiler warnings before you compile.
  • NUnit
    These inspections detect code issues related to NUnit tests.
  • Formatting
    Inspections in this category detect code code formatting problems.

Identifiers of configurable code inspections

Each configurable code inspection has two unique identifiers that you can use to configure it. Let's take the Possible 'System.NullReferenceException' inspection as an example:

  • Inspection ID is used to suppress the inspection with a comment —
    // ReSharper disable once PossibleNullReferenceException for a single issue or
    // ReSharper disable PossibleNullReferenceException till the end of the file,
    or with an attribute —
    [SuppressMessage("ReSharper", "PossibleNullReferenceException")].
  • Inspection EditorConfig property can be used to configure the inspection from .editorconfig files. For example, you can change the inspection's severity level to Error with the following line:
    resharper_possible_null_reference_exception_highlighting=error

You can find identifiers for each configurable inspection in the Code Inspection Index — just choose a language page and then use the browser search to find the details of the desired inspection.

 

Last modified: 11 July 2018

See Also