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ide0302fundamentals/code-analysis/style-rules

Code analysis

Use collection expression for stackalloc (IDE0302)

Learn about code analysis rule IDE0302: Use collection expression for stackalloc

IDE0302 Style / Language rules (expression-level preferences)
Applicable languages C# 12+Options dotnet_style_prefer_collection_expression

Overview

This rule is similar to Use collection expression for array (IDE0300) except it looks for stackalloc instead of arrays. Like IDE0300, it offers to convert the code to use a collection expression. For example, stackalloc int[] { ... } and stackalloc [] { ... } are simplified to [...].

Options

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

ms.topic: include

dotnet_style_prefer_collection_expression

Property Value Description
Option name dotnet_style_prefer_collection_expression
Option values true | when_types_exactly_match Prefer to use collection expressions only when types match exactly, for example, List<int> list = new List<int>() { 1, 2 };.
when_types_loosely_match* Prefer to use collection expressions even when types match loosely, for example, IEnumerable<int> list = new List<int>() { 1, 2 };. The targeted type must match the type on the right-hand side or be one of the following types: System.Collections.Generic.IEnumerable, System.Collections.Generic.ICollection, System.Collections.Generic.IList, System.Collections.Generic.IReadOnlyCollection, System.Collections.Generic.IReadOnlyList.
false | never Disables the rule.
Default option value when_types_loosely_match*

*When this option is used, the code fix might change the semantics of your code.

The when_types_loosely_match value for does not apply to this rule IDE0302, but is listed here for completeness of the dotnet_style_prefer_collection_expression option (which is shared by multiple rules). The default value is effectively true.

Example

csharp
// Code with violations.
ReadOnlySpan<int> x = stackalloc int[] { 1, 2, 3 };

// Fixed code.
ReadOnlySpan<int> x = [1, 2, 3];

Suppress a warning

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

csharp
#pragma warning disable IDE0302
// The code that's violating the rule is on this line.
#pragma warning restore IDE0302

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

ini
[*.{cs,vb}]
dotnet_diagnostic.IDE0302.severity = none

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

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

For more information, see How to suppress code analysis warnings.

See also