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Fix for UseDeconstruction with default literal #26140

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Merged
jcouv merged 3 commits into from
Apr 16, 2018
Merged

Fix for UseDeconstruction with default literal #26140

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2f05fbe
Fixing test & checking for conversion instead of type
Neme12 Apr 13, 2018
b9221df
Using a better example of tuple literal conversion
Neme12 Apr 13, 2018
8fc5180
Adding a comment
Neme12 Apr 13, 2018
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25 changes: 24 additions & 1 deletion src/EditorFeatures/CSharpTest/UseDeconstruction/UseDeconstructionTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,7 @@

using System.Threading.Tasks;
using Microsoft.CodeAnalysis.CodeFixes;
using Microsoft.CodeAnalysis.CSharp;
using Microsoft.CodeAnalysis.CSharp.UseDeconstruction;
using Microsoft.CodeAnalysis.Diagnostics;
using Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.Diagnostics;
Expand Down Expand Up @@ -481,7 +482,7 @@ void M()
(string name, int age) [|person|] = default;
Console.WriteLine(person.name + "" "" + person.age);
}
}");
}", new TestParameters(parseOptions: CSharpParseOptions.Default.WithLanguageVersion(LanguageVersion.CSharp7_1)));
}

[Fact, Trait(Traits.Feature, Traits.Features.CodeActionsUseDeconstruction)]
Expand Down Expand Up @@ -610,6 +611,28 @@ void M()
}");
}

[Fact, Trait(Traits.Feature, Traits.Features.CodeActionsUseDeconstruction)]
public async Task TestWithTupleLiteralConversion()
{
await TestInRegularAndScriptAsync(
@"class C
{
void M()
{
(object name, double age) [|person|] = (null, 0);
Console.WriteLine(person.name + "" "" + person.age);
}
}",
@"class C
{
void M()
{
(object name, double age) = (null, 0);
Console.WriteLine(name + "" "" + age);
}
}");
}

[Fact, Trait(Traits.Feature, Traits.Features.CodeActionsUseDeconstruction)]
public async Task TestWithImplicitTupleConversion()
{
Expand Down
26 changes: 19 additions & 7 deletions src/Features/CSharp/Portable/UseDeconstruction/CSharpUseDeconstructionDiagnosticAnalyzer.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -125,10 +125,10 @@ public static bool TryAnalyzeVariableDeclaration(
}

var local = (ILocalSymbol)semanticModel.GetDeclaredSymbol(declarator, cancellationToken);
var expressionType = semanticModel.GetTypeInfo(declarator.Initializer.Value, cancellationToken).Type;
var initializerConversion = semanticModel.GetConversion(declarator.Initializer.Value, cancellationToken);

return TryAnalyze(
semanticModel, local, variableDeclaration.Type, declarator.Identifier, expressionType,
semanticModel, local, variableDeclaration.Type, declarator.Identifier, initializerConversion,
variableDeclaration.Parent.Parent, out tupleType, out memberAccessExpressions, cancellationToken);
}

Expand All @@ -140,10 +140,10 @@ public static bool TryAnalyzeForEachStatement(
CancellationToken cancellationToken)
{
var local = semanticModel.GetDeclaredSymbol(forEachStatement, cancellationToken);
var elementType = semanticModel.GetForEachStatementInfo(forEachStatement).ElementType;
var elementConversion = semanticModel.GetForEachStatementInfo(forEachStatement).ElementConversion;

return TryAnalyze(
semanticModel, local, forEachStatement.Type, forEachStatement.Identifier, elementType,
semanticModel, local, forEachStatement.Type, forEachStatement.Identifier, elementConversion,
forEachStatement, out tupleType, out memberAccessExpressions, cancellationToken);
}

Expand All @@ -152,7 +152,7 @@ private static bool TryAnalyze(
ILocalSymbol local,
TypeSyntax typeNode,
SyntaxToken identifier,
ITypeSymbol initializerType,
Conversion conversion,
SyntaxNode searchScope,
out INamedTypeSymbol tupleType,
out ImmutableArray<MemberAccessExpressionSyntax> memberAccessExpressions,
Expand All @@ -171,9 +171,21 @@ private static bool TryAnalyze(
return false;
}

if (conversion.Exists &&
!conversion.IsIdentity &&
!conversion.IsTupleConversion &&
!conversion.IsTupleLiteralConversion)
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@CyrusNajmabadi CyrusNajmabadi Apr 13, 2018

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probably would benefit from a comment.

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@Neme12 Neme12 Apr 13, 2018

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comment added

{
// If there is any other conversion, we bail out because the source type might not be a tuple
// or it is a tuple but only thanks to target type inference, which won't occur in a deconstruction.
// Interesting case that illustrates this is initialization with a default literal:
// (int a, int b) t = default;
// This is classified as conversion.IsNullLiteral.
return false;
}

var type = semanticModel.GetTypeInfo(typeNode, cancellationToken).Type;
if (type == null || !type.IsTupleType ||
initializerType == null || !initializerType.IsTupleType)
if (type == null || !type.IsTupleType)
{
return false;
}
Expand Down