Properly iterate through an inline array used as a spread element. (#…

…75151) Fixes #70708;
dotnet · Sep 18, 2024 · 2c8a815 · 2c8a815
1 parent a182892
commit 2c8a815
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Showing 4 changed files with 556 additions and 72 deletions.
diff --git a/src/Compilers/CSharp/Portable/Binder/Binder_Expressions.cs b/src/Compilers/CSharp/Portable/Binder/Binder_Expressions.cs
@@ -5209,11 +5209,20 @@ static BoundNode bindSpreadElement(SpreadElementSyntax syntax, BindingDiagnostic
                 Debug.Assert(conversion.IsValid);
                 diagnostics.Add(syntax.Expression, useSiteInfo);
                 var convertedExpression = @this.ConvertForEachCollection(expressionPlaceholder, conversion, collectionType, diagnostics);
+
                 BoundExpression? lengthOrCount;
-                if (!@this.TryBindLengthOrCount(syntax.Expression, expressionPlaceholder, out lengthOrCount, diagnostics))
+
+                if (enumeratorInfo is { InlineArraySpanType: not WellKnownType.Unknown })
+                {
+                    _ = expression.Type.HasInlineArrayAttribute(out int length);
+                    Debug.Assert(length > 0);
+                    lengthOrCount = new BoundLiteral(expression.Syntax, ConstantValue.Create(length), @this.GetSpecialType(SpecialType.System_Int32, diagnostics, expression.Syntax)) { WasCompilerGenerated = true };
+                }
+                else if (!@this.TryBindLengthOrCount(syntax.Expression, expressionPlaceholder, out lengthOrCount, diagnostics))
                 {
                     lengthOrCount = null;
                 }
+
                 return new BoundCollectionExpressionSpreadElement(
                     syntax,
                     expression,

diff --git a/src/Compilers/CSharp/Portable/Lowering/LocalRewriter/LocalRewriter_CollectionExpression.cs b/src/Compilers/CSharp/Portable/Lowering/LocalRewriter/LocalRewriter_CollectionExpression.cs
@@ -1327,6 +1327,24 @@ private BoundExpression MakeCollectionExpressionSpreadElement(
                         rewrittenBody);
                 }
             }
+            else if (enumeratorInfo is { InlineArraySpanType: not WellKnownType.Unknown })
+            {
+                statement = RewriteForEachStatementAsFor(
+                    node,
+                    getPreamble: GetInlineArrayForEachStatementPreambleDelegate(),
+                    getItem: GetInlineArrayForEachStatementGetItemDelegate(),
+                    getLength: GetInlineArrayForEachStatementGetLengthDelegate(),
+                    arg: null,
+                    convertedExpression.Operand,
+                    enumeratorInfo,
+                    elementPlaceholder: null,
+                    elementConversion: null,
+                    iterationVariables,
+                    deconstructionOpt: null,
+                    breakLabel,
+                    continueLabel,
+                    rewrittenBody);
+            }
             else
             {
                 statement = RewriteForEachEnumerator(