[release/10.0.3xx] Fix CA1825 false positive on collection expressions

[akhera99]

Backports: #53521
Original issue: dotnet/roslyn#82484

Description

Fixes #54275 where, starting in 10.0.3xx, the compiler lowers collection expressions and CA1825 incorrectly flagged these as zero-length array allocations. The code fixer crashed with an InvalidCastException when the target type wasn't an array. This PR adds a check to bail out when the array creation syntax originates from a collectionexpression, and switches from a direct cast to an as cast in the fixer.

Customer impact

Customer-reported (#54275, #53047). Users on SDK 10.0.300 see CA1825 warnings on any code using collection expressions. The fixer also crashes, making the experience worse.

Regression

Yes, this regressed in 10.0.300. The compiler's collection-expression lowering is new, and the existing CA1825 analyzer didn't account for it.

Risk

Low. The change is small, tightly scoped to the CA1825 analyzer/fixer, does not affect other analyzers or SDK behavior, and includes three new unit tests covering the scenarios.

[Copilot]

Pull request overview

Backports #53521 to release/10.0.3xx to address a CA1825 false positive (and related code-fix crash) caused by C# collection expressions lowering to compiler-generated array creation operations.

Changes:

• Skip CA1825 analysis for array-creation operations whose syntax originates from a C# collection expression.
• Make the code fix resilient to non-array target types by switching to a safe as cast when deriving the array element type.
• Add regression tests covering collection-expression scenarios (non-array target, array target, and explicit new int[0] inside a collection expression).

Show a summary per file

File	Description
src/Microsoft.CodeAnalysis.NetAnalyzers/tests/Microsoft.CodeAnalysis.NetAnalyzers.UnitTests/Microsoft.NetCore.Analyzers/Runtime/AvoidZeroLengthArrayAllocationsTests.cs	Adds C#12 collection-expression regression tests (no diagnostic for lowered compiler arrays; diagnostic still for explicit new int[0]).
src/Microsoft.CodeAnalysis.NetAnalyzers/src/Microsoft.CodeAnalysis.VisualBasic.NetAnalyzers/Microsoft.NetCore.Analyzers/Runtime/BasicAvoidZeroLengthArrayAllocationsAnalyzer.vb	Implements the new collection-expression hook for VB (returns False, since VB has no collection expressions).
src/Microsoft.CodeAnalysis.NetAnalyzers/src/Microsoft.CodeAnalysis.NetAnalyzers/Microsoft.NetCore.Analyzers/Runtime/AvoidZeroLengthArrayAllocations.Fixer.cs	Prevents InvalidCastException by using as IArrayTypeSymbol when extracting element type.
src/Microsoft.CodeAnalysis.NetAnalyzers/src/Microsoft.CodeAnalysis.NetAnalyzers/Microsoft.NetCore.Analyzers/Runtime/AvoidZeroLengthArrayAllocations.cs	Adds IsCollectionExpressionSyntax abstraction and bails out early for collection-expression-originated syntax.
src/Microsoft.CodeAnalysis.NetAnalyzers/src/Microsoft.CodeAnalysis.CSharp.NetAnalyzers/Microsoft.NetCore.Analyzers/Runtime/CSharpAvoidZeroLengthArrayAllocations.cs	Implements IsCollectionExpressionSyntax for C# via SyntaxKindEx.CollectionExpression.

Copilot's findings

• Files reviewed: 5/5 changed files
• Comments generated: 0