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Ensure an empty run result doesn't throw when generators are present. #74034

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merged 4 commits into from
Jun 26, 2024
Merged

Ensure an empty run result doesn't throw when generators are present. #74034

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f6c6fbf
Ensure an empty run result doesn't throw when generators are present.
chsienki Jun 17, 2024
2bf0845
Split into empty and unitialized
chsienki Jun 18, 2024
8238e9b
Remove uninit state and handle default instances instead
chsienki Jun 21, 2024
f50a499
Remove init
chsienki Jun 21, 2024
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22 changes: 22 additions & 0 deletions src/Compilers/CSharp/Test/Semantic/SourceGeneration/GeneratorDriverTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -550,6 +550,28 @@ public void RunResults_Are_Empty_Before_Generation()
Assert.Empty(results.Results);
}

[Fact, WorkItem("https://github.com/dotnet/roslyn/issues/74033")]
public void RunResults_Are_Empty_Before_Generation_With_Generators()
{
var generator = new SingleFileTestGenerator("public class D {}", "source.cs");

GeneratorDriver driver = CSharpGeneratorDriver.Create([generator], parseOptions: TestOptions.Regular);
var results = driver.GetRunResult();

Assert.Empty(results.GeneratedTrees);
Assert.Empty(results.Diagnostics);

var result = Assert.Single(results.Results);

Assert.Null(result.Exception);
Assert.Empty(result.Diagnostics);
Assert.Empty(result.GeneratedSources);
Assert.Empty(result.TrackedSteps);
Assert.Empty(result.TrackedOutputSteps);
Assert.Equal(TimeSpan.Zero, result.ElapsedTime);
Assert.Equal(generator, result.Generator);
}

[Fact]
public void RunResults_Are_Available_After_Generation()
{
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2 changes: 1 addition & 1 deletion src/Compilers/Core/Portable/SourceGeneration/GeneratorDriver.cs
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Expand Up @@ -39,7 +39,7 @@ internal GeneratorDriver(GeneratorDriverState state)
internal GeneratorDriver(ParseOptions parseOptions, ImmutableArray<ISourceGenerator> generators, AnalyzerConfigOptionsProvider optionsProvider, ImmutableArray<AdditionalText> additionalTexts, GeneratorDriverOptions driverOptions)
{
var incrementalGenerators = GetIncrementalGenerators(generators, SourceExtension);
_state = new GeneratorDriverState(parseOptions, optionsProvider, generators, incrementalGenerators, additionalTexts, ImmutableArray.Create(new GeneratorState[generators.Length]), DriverStateTable.Empty, SyntaxStore.Empty, driverOptions, runtime: TimeSpan.Zero, parseOptionsChanged: true);
_state = new GeneratorDriverState(parseOptions, optionsProvider, generators, incrementalGenerators, additionalTexts, generators.SelectAsArray(g => GeneratorState.Empty), DriverStateTable.Empty, SyntaxStore.Empty, driverOptions, runtime: TimeSpan.Zero, parseOptionsChanged: true);
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Could you please explain how this change prevents an NRE which was occurring in the original code?

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I'm guessing it's in getGeneratorSources access to generatorState.PostInitTrees.Length. The value for PostInitTrees is a default immutable array for default(GeneratorState), as opposed to an empty immutable array for GeneratorState.Empty.

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When calling .GetRunResult() we call into a local function getGeneratorSources that creates an array to handle the generated sources of the given generator

roslyn/src/Compilers/Core/Portable/SourceGeneration/GeneratorDriver.cs

Line 174 in b8320e1

ArrayBuilder<GeneratedSourceResult> sources = ArrayBuilder<GeneratedSourceResult>.GetInstance(generatorState.PostInitTrees.Length + generatorState.GeneratedTrees.Length);

That calls into the collections of the individual states to get their sizes. Prior to the change, we created default GeneratorStates, so the PostInitTrees and GeneratedTrees were uninitialized immutable arrays which throw when attempting to get their length.

Instead we now store GeneratorState.Empty instances, which in turn have empty result arrays rather than uninitialized ones.

We had a test that checked you could call GetRunResult before calling RunGenerators but that test didn't add any generators, so the generatorStates array was empty. Adding a generator ensures that array has content, and we see the issue in the added test.

}

public GeneratorDriver RunGenerators(Compilation compilation, CancellationToken cancellationToken = default)
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