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Merged
merged 15 commits into from
Nov 14, 2025
Merged

Filter IntelliSense attribute suggestions by AttributeTargets #81157

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3a09a5d
Initial plan
Copilot Nov 11, 2025
c780868
Implement attribute target filtering for IntelliSense
Copilot Nov 11, 2025
a95e595
Cache ValidAttributeTargets to avoid expensive recomputation
Copilot Nov 11, 2025
51cfa91
Update src/Workspaces/SharedUtilitiesAndExtensions/Workspace/CSharp/E…
CyrusNajmabadi Nov 11, 2025
bd67526
Add comprehensive tests and use pattern matching improvements
Copilot Nov 11, 2025
8fc6527
Add tests
CyrusNajmabadi Nov 11, 2025
0a0d8ce
Update parser
CyrusNajmabadi Nov 11, 2025
78d6908
Use 'field'
CyrusNajmabadi Nov 11, 2025
13d6ec2
Update logic and add tests
CyrusNajmabadi Nov 12, 2025
286d305
More precise check
CyrusNajmabadi Nov 12, 2025
01e2862
Simplify
CyrusNajmabadi Nov 12, 2025
df40d59
Revert compiler side
CyrusNajmabadi Nov 14, 2025
f463828
Merge remote-tracking branch 'upstream/main' into copilot/update-inte…
CyrusNajmabadi Nov 14, 2025
dc37782
Add test
CyrusNajmabadi Nov 14, 2025
3424a47
Update test
CyrusNajmabadi Nov 14, 2025
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56 changes: 45 additions & 11 deletions src/Compilers/CSharp/Portable/Parser/LanguageParser.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -5956,8 +5956,41 @@ private bool IsStartOfTypeParameter()
return false;

// possible attributes
if (this.CurrentToken.Kind == SyntaxKind.OpenBracketToken && this.PeekToken(1).Kind != SyntaxKind.CloseBracketToken)
return true;
if (this.CurrentToken.Kind == SyntaxKind.OpenBracketToken)
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@CyrusNajmabadi CyrusNajmabadi Nov 12, 2025

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ok. i was actually able to simplify this to just:

            // possible attributes.
            // Variance.
            if (this.CurrentToken.Kind is SyntaxKind.OpenBracketToken or SyntaxKind.InKeyword or SyntaxKind.OutKeyword)
                return true;

and i got no regressions (in the syntax tests at least). i'm going to go with that much simpler approach as i don't really see a reason why we would accept [ <non-close-brace as an attribute, but not [] as well.

{
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@CyrusNajmabadi CyrusNajmabadi Nov 11, 2025

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i would also be fine simplifying this so that we always return true when we see [ regardless of what follows.

var nextKind = this.PeekToken(1).Kind;
// [...
// The start of an attribute on a type parameter.
if (nextKind != SyntaxKind.CloseBracketToken)
return true;

// We have `[]`. Recover from a partially written attribute.
//
// <[] ,
// <[] >
// <[] in/out
// <[] { ...
if (nextKind is SyntaxKind.CommaToken
or SyntaxKind.GreaterThanToken
or SyntaxKind.InKeyword
or SyntaxKind.OutKeyword
or SyntaxKind.OpenBraceToken)
{
return true;
}

// <[] where
// <[] partial
//
// Parsing a type parameter will see this and treat the 'where' appropriately if it is the start
// of a where-clause or not. Similarly for 'partial' and if it is a keyword, or just an identifier.
if (this.PeekToken(1).ContextualKind is SyntaxKind.WhereKeyword or SyntaxKind.PartialKeyword)
return true;

using var _ = this.GetDisposableResetPoint(resetOnDispose: true);
this.EatToken(); // eat '['
return IsTrueIdentifier();
}

// Variance.
if (this.CurrentToken.Kind is SyntaxKind.InKeyword or SyntaxKind.OutKeyword)
Expand All @@ -5968,23 +6001,24 @@ private bool IsStartOfTypeParameter()

private TypeParameterSyntax ParseTypeParameter()
{
if (this.IsCurrentTokenWhereOfConstraintClause())
{
return _syntaxFactory.TypeParameter(
default(SyntaxList<AttributeListSyntax>),
varianceKeyword: null,
this.AddError(CreateMissingIdentifierToken(), ErrorCode.ERR_IdentifierExpected));
}

var attrs = default(SyntaxList<AttributeListSyntax>);
if (this.CurrentToken.Kind == SyntaxKind.OpenBracketToken && this.PeekToken(1).Kind != SyntaxKind.CloseBracketToken)
if (this.CurrentToken.Kind == SyntaxKind.OpenBracketToken)
{
var saveTerm = _termState;
_termState = TerminatorState.IsEndOfTypeArgumentList;
attrs = this.ParseAttributeDeclarations(inExpressionContext: false);
_termState = saveTerm;
}

if (this.IsCurrentTokenWhereOfConstraintClause() ||
this.IsCurrentTokenPartialKeywordOfPartialMemberOrType())
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@CyrusNajmabadi CyrusNajmabadi Nov 12, 2025

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tests added for this case.

{
return _syntaxFactory.TypeParameter(
attrs,
varianceKeyword: null,
this.AddError(CreateMissingIdentifierToken(), ErrorCode.ERR_IdentifierExpected));
}

return _syntaxFactory.TypeParameter(
attrs,
this.CurrentToken.Kind is SyntaxKind.InKeyword or SyntaxKind.OutKeyword ? EatToken() : null,
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