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Fix parser regressions of conditional expressions #75075

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merged 6 commits into from
Sep 24, 2024
Merged

Fix parser regressions of conditional expressions #75075

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222b836
Fix regression of parsing `with` expression in conditional expression
DoctorKrolic Sep 12, 2024
edb7723
Fix linq query parsing
DoctorKrolic Sep 12, 2024
4c36ed9
Merge branch 'dotnet:main' into with-parsing-regression
DoctorKrolic Sep 19, 2024
11ab036
More `await` tests
DoctorKrolic Sep 21, 2024
af05256
Add `global` test
DoctorKrolic Sep 21, 2024
af02bf2
Add `yield` tests
DoctorKrolic Sep 21, 2024
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17 changes: 12 additions & 5 deletions src/Compilers/CSharp/Portable/Parser/LanguageParser.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -7425,16 +7425,23 @@ bool canFollowNullableType()
// nullable-typed pattern
if (IsTrueIdentifier(this.CurrentToken))
{
// In a non-async method, `await` is a simple identifier. However, if we see `x ? await`
// 1. `async` can start a simple lambda in a conditional expression
// (e.g. `x is Y ? async a => ...`). The correct behavior is to treat `async` as a keyword
// 2. In a non-async method, `await` is a simple identifier. However, if we see `x ? await`
// it's almost certainly the start of an `await expression` in a conditional expression
// (e.g. `x is Y ? await ...`), not a nullable type pattern (since users would not use
// 'await' as the name of a variable). So just treat this as a conditional expression.
// Similarly, `async` can start a simple lambda in a conditional expression
// (e.g. `x is Y ? async a => ...`). The correct behavior is to treat `async` as a keyword
if (this.CurrentToken.ContextualKind is SyntaxKind.AsyncKeyword or SyntaxKind.AwaitKeyword)
// 3. `from` most likely starts a linq query: `x is Y ? from item in collection select item : ...`
if (this.CurrentToken.ContextualKind is SyntaxKind.AsyncKeyword or SyntaxKind.AwaitKeyword or SyntaxKind.FromKeyword)
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return false;

var nextToken = PeekToken(1);

// Cases like `x is Y ? someRecord with { } : ...`
if (nextToken.ContextualKind == SyntaxKind.WithKeyword)
return false;

var nextTokenKind = PeekToken(1).Kind;
var nextTokenKind = nextToken.Kind;

// These token either 100% end a pattern or start a new one:

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201 changes: 201 additions & 0 deletions src/Compilers/CSharp/Test/Syntax/Parsing/ExpressionParsingTests.cs
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Do we have tests for:

  • global
  • yield

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Added a test for global qualified name. As of yield, since it is only valid as a yield return and yield break statements, it cannot be a contextual keyword inside an expression. However, this gave me an idea: if we have something like x is X ? yield return 0 ... we can parse it a lot better we we consider x is X? yield as one statement and return 0 ... as another one with missing ; in between. This is actually true for most keywords that start a statement: if, while, for etc. For now I added 2 yield tests with the right shape to just swap the errors and parse result in the future, but when main branch targets 17.13, I'm gnna make a follow-up PR with imrpoved error recovery for such cases

Original file line number Diff line number Diff line change
Expand Up @@ -6822,5 +6822,206 @@ public void UnsignedRightShiftAssignment_04()
EOF();
}
}

[Fact, WorkItem("https://github.com/dotnet/roslyn/issues/75074")]
public void LinqQueryInConditionalExpression1()
{
var text = "x is X ? from item in collection select item : null";

UsingExpression(text);
N(SyntaxKind.ConditionalExpression);
{
N(SyntaxKind.IsExpression);
{
N(SyntaxKind.IdentifierName);
{
N(SyntaxKind.IdentifierToken, "x");
}
N(SyntaxKind.IsKeyword);
N(SyntaxKind.IdentifierName);
{
N(SyntaxKind.IdentifierToken, "X");
}
}
N(SyntaxKind.QuestionToken);
N(SyntaxKind.QueryExpression);
{
N(SyntaxKind.FromClause);
{
N(SyntaxKind.FromKeyword);
N(SyntaxKind.IdentifierToken, "item");
N(SyntaxKind.InKeyword);
N(SyntaxKind.IdentifierName);
{
N(SyntaxKind.IdentifierToken, "collection");
}
}
N(SyntaxKind.QueryBody);
{
N(SyntaxKind.SelectClause);
{
N(SyntaxKind.SelectKeyword);
N(SyntaxKind.IdentifierName);
{
N(SyntaxKind.IdentifierToken, "item");
}
}
}
}
N(SyntaxKind.ColonToken);
N(SyntaxKind.NullLiteralExpression);
{
N(SyntaxKind.NullKeyword);
}
}
EOF();
}

[Fact, WorkItem("https://github.com/dotnet/roslyn/issues/75074")]
public void LinqQueryInConditionalExpression2()
{
var text = "x is X.Y ? from item in collection select item : null";

UsingExpression(text);
N(SyntaxKind.ConditionalExpression);
{
N(SyntaxKind.IsExpression);
{
N(SyntaxKind.IdentifierName);
{
N(SyntaxKind.IdentifierToken, "x");
}
N(SyntaxKind.IsKeyword);
N(SyntaxKind.QualifiedName);
{
N(SyntaxKind.IdentifierName);
{
N(SyntaxKind.IdentifierToken, "X");
}
N(SyntaxKind.DotToken);
N(SyntaxKind.IdentifierName);
{
N(SyntaxKind.IdentifierToken, "Y");
}
}
}
N(SyntaxKind.QuestionToken);
N(SyntaxKind.QueryExpression);
{
N(SyntaxKind.FromClause);
{
N(SyntaxKind.FromKeyword);
N(SyntaxKind.IdentifierToken, "item");
N(SyntaxKind.InKeyword);
N(SyntaxKind.IdentifierName);
{
N(SyntaxKind.IdentifierToken, "collection");
}
}
N(SyntaxKind.QueryBody);
{
N(SyntaxKind.SelectClause);
{
N(SyntaxKind.SelectKeyword);
N(SyntaxKind.IdentifierName);
{
N(SyntaxKind.IdentifierToken, "item");
}
}
}
}
N(SyntaxKind.ColonToken);
N(SyntaxKind.NullLiteralExpression);
{
N(SyntaxKind.NullKeyword);
}
}
EOF();
}

[Fact, WorkItem("https://github.com/dotnet/roslyn/issues/75074")]
public void LinqQueryInConditionalExpression_Incomplete()
{
var text = "x is X.Y ? from item";

UsingExpression(text,
// (1,21): error CS1001: Identifier expected
// x is X.Y ? from item
Diagnostic(ErrorCode.ERR_IdentifierExpected, "").WithLocation(1, 21),
// (1,21): error CS1003: Syntax error, 'in' expected
// x is X.Y ? from item
Diagnostic(ErrorCode.ERR_SyntaxError, "").WithArguments("in").WithLocation(1, 21),
// (1,21): error CS1733: Expected expression
// x is X.Y ? from item
Diagnostic(ErrorCode.ERR_ExpressionExpected, "").WithLocation(1, 21),
// (1,21): error CS0742: A query body must end with a select clause or a group clause
// x is X.Y ? from item
Diagnostic(ErrorCode.ERR_ExpectedSelectOrGroup, "").WithLocation(1, 21),
// (1,21): error CS1003: Syntax error, ':' expected
// x is X.Y ? from item
Diagnostic(ErrorCode.ERR_SyntaxError, "").WithArguments(":").WithLocation(1, 21),
// (1,21): error CS1733: Expected expression
// x is X.Y ? from item
Diagnostic(ErrorCode.ERR_ExpressionExpected, "").WithLocation(1, 21));

N(SyntaxKind.ConditionalExpression);
{
N(SyntaxKind.IsExpression);
{
N(SyntaxKind.IdentifierName);
{
N(SyntaxKind.IdentifierToken, "x");
}
N(SyntaxKind.IsKeyword);
N(SyntaxKind.QualifiedName);
{
N(SyntaxKind.IdentifierName);
{
N(SyntaxKind.IdentifierToken, "X");
}
N(SyntaxKind.DotToken);
N(SyntaxKind.IdentifierName);
{
N(SyntaxKind.IdentifierToken, "Y");
}
}
}
N(SyntaxKind.QuestionToken);
N(SyntaxKind.QueryExpression);
{
N(SyntaxKind.FromClause);
{
N(SyntaxKind.FromKeyword);
N(SyntaxKind.IdentifierName);
{
N(SyntaxKind.IdentifierToken, "item");
}
M(SyntaxKind.IdentifierToken);
M(SyntaxKind.InKeyword);
M(SyntaxKind.IdentifierName);
{
M(SyntaxKind.IdentifierToken);
}
}
M(SyntaxKind.QueryBody);
{
M(SyntaxKind.SelectClause);
{
M(SyntaxKind.SelectKeyword);
M(SyntaxKind.IdentifierName);
{
M(SyntaxKind.IdentifierToken);
}
}
}
}
M(SyntaxKind.ColonToken);
M(SyntaxKind.IdentifierName);
{
M(SyntaxKind.IdentifierToken);
}
}
EOF();
}
}
}
150 changes: 150 additions & 0 deletions src/Compilers/CSharp/Test/Syntax/Parsing/RecordParsing.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -2099,6 +2099,156 @@ public void WithParsing19()
EOF();
}

[Fact, WorkItem("https://github.com/dotnet/roslyn/issues/75074")]
public void WithParsingInConditionalExpression1()
{
var text = "x is X ? record with { } : record with { }";

UsingExpression(text);
N(SyntaxKind.ConditionalExpression);
{
N(SyntaxKind.IsExpression);
{
N(SyntaxKind.IdentifierName);
{
N(SyntaxKind.IdentifierToken, "x");
}
N(SyntaxKind.IsKeyword);
N(SyntaxKind.IdentifierName);
{
N(SyntaxKind.IdentifierToken, "X");
}
}
N(SyntaxKind.QuestionToken);
N(SyntaxKind.WithExpression);
{
N(SyntaxKind.IdentifierName);
{
N(SyntaxKind.IdentifierToken, "record");
}
N(SyntaxKind.WithKeyword);
N(SyntaxKind.WithInitializerExpression);
{
N(SyntaxKind.OpenBraceToken);
N(SyntaxKind.CloseBraceToken);
}
}
N(SyntaxKind.ColonToken);
N(SyntaxKind.WithExpression);
{
N(SyntaxKind.IdentifierName);
{
N(SyntaxKind.IdentifierToken, "record");
}
N(SyntaxKind.WithKeyword);
N(SyntaxKind.WithInitializerExpression);
{
N(SyntaxKind.OpenBraceToken);
N(SyntaxKind.CloseBraceToken);
}
}
}
EOF();
}

[Fact, WorkItem("https://github.com/dotnet/roslyn/issues/75074")]
public void WithParsingInConditionalExpression2()
{
var text = "x is X.Y ? record with { } : record with { }";

UsingExpression(text);
N(SyntaxKind.ConditionalExpression);
{
N(SyntaxKind.IsExpression);
{
N(SyntaxKind.IdentifierName);
{
N(SyntaxKind.IdentifierToken, "x");
}
N(SyntaxKind.IsKeyword);
N(SyntaxKind.QualifiedName);
{
N(SyntaxKind.IdentifierName);
{
N(SyntaxKind.IdentifierToken, "X");
}
N(SyntaxKind.DotToken);
N(SyntaxKind.IdentifierName);
{
N(SyntaxKind.IdentifierToken, "Y");
}
}
}
N(SyntaxKind.QuestionToken);
N(SyntaxKind.WithExpression);
{
N(SyntaxKind.IdentifierName);
{
N(SyntaxKind.IdentifierToken, "record");
}
N(SyntaxKind.WithKeyword);
N(SyntaxKind.WithInitializerExpression);
{
N(SyntaxKind.OpenBraceToken);
N(SyntaxKind.CloseBraceToken);
}
}
N(SyntaxKind.ColonToken);
N(SyntaxKind.WithExpression);
{
N(SyntaxKind.IdentifierName);
{
N(SyntaxKind.IdentifierToken, "record");
}
N(SyntaxKind.WithKeyword);
N(SyntaxKind.WithInitializerExpression);
{
N(SyntaxKind.OpenBraceToken);
N(SyntaxKind.CloseBraceToken);
}
}
}
EOF();
}

[Fact, WorkItem("https://github.com/dotnet/roslyn/issues/75074")]
public void WithParsingInConditionalExpression_Incomplete()
{
var text = "x is X ? record with";

UsingExpression(text,
// (1,17): error CS1003: Syntax error, ':' expected
// x is X ? record with
Diagnostic(ErrorCode.ERR_SyntaxError, "with").WithArguments(":").WithLocation(1, 17));

N(SyntaxKind.ConditionalExpression);
{
N(SyntaxKind.IsExpression);
{
N(SyntaxKind.IdentifierName);
{
N(SyntaxKind.IdentifierToken, "x");
}
N(SyntaxKind.IsKeyword);
N(SyntaxKind.IdentifierName);
{
N(SyntaxKind.IdentifierToken, "X");
}
}
N(SyntaxKind.QuestionToken);
N(SyntaxKind.IdentifierName);
{
N(SyntaxKind.IdentifierToken, "record");
}
M(SyntaxKind.ColonToken);
N(SyntaxKind.IdentifierName);
{
N(SyntaxKind.IdentifierToken, "with");
}
}
EOF();
}

[Fact]
public void ParameterListAndBaseListOnClass()
{
Expand Down