Member can be made 'readonly' (IDE0251)

Property	Value
Rule ID	IDE0251
Title	Member can be made 'readonly'
Category	Style
Subcategory	Language rules (modifier preferences)
Applicable languages	C# 8+
Options	`csharp_style_prefer_readonly_struct_member`

Overview

This rule flags members of non-readonly structs that aren't marked readonly that could be marked as readonly.

Options specify the behavior that you want the rule to enforce. For information about configuring options, see Option format.

Property	Value	Description
Option name	csharp_style_prefer_readonly_struct_member
Option values	`true`	Prefer to make struct members `readonly`.
	`false`	Disables the rule.
Default option value	`true`

// Code with violations.
struct S
{
    void M() { }
}

// Fixed code.
struct S
{
    readonly void M() { }
}

If you want to suppress only a single violation, add preprocessor directives to your source file to disable and then re-enable the rule.

#pragma warning disable IDE0251
// The code that's violating the rule is on this line.
#pragma warning restore IDE0251

To disable the rule for a file, folder, or project, set its severity to none in the configuration file.

[*.{cs,vb}]
dotnet_diagnostic.IDE0251.severity = none

To disable all of the code-style rules, set the severity for the category Style to none in the configuration file.

[*.{cs,vb}]
dotnet_analyzer_diagnostic.category-Style.severity = none