Don't offer convert to switch when an implicit cast is present by davidwengier · Pull Request #60224 · dotnet/roslyn

davidwengier · 2022-03-17T06:08:46Z

src/EditorFeatures/CSharpTest/CodeActions/ConvertIfToSwitch/ConvertIfToSwitchTests.cs

Youssef1313

It might worth adding tests that are expected to produce switch expressions rather than switch statements. Something similar to this test (but involves implicit cast)

roslyn/src/EditorFeatures/CSharpTest/CodeActions/ConvertIfToSwitch/ConvertIfToSwitchTests.cs

Lines 889 to 914 in 99e81ec

    
                   [Fact, Trait(Traits.Feature, Traits.Features.CodeActionsConvertIfToSwitch)] 
        
                   public async Task TestSwitchExpression_01() 
        
                   { 
        
                       var source = 
        
                           @"class C 
        
           { 
        
               int M(int? i) 
        
               { 
        
                   $$if (i == null) return 5; 
        
                   if (i == 0) return 6; 
        
                   return 7; 
        
               } 
        
           }"; 
        
                       var fixedSource = 
        
           @"class C 
        
           { 
        
               int M(int? i) 
        
               { 
        
                   return i switch 
        
                   { 
        
                       null => 5, 
        
                       0 => 6, 
        
                       _ => 7 
        
                   }; 
        
               } 
        
           }";

~~I'd expect the implicit cast to be turned into explicit cast for this case too.~~ Edit per #60224 (comment)

...Core/Portable/ConvertIfToSwitch/AbstractConvertIfToSwitchCodeRefactoringProvider.Analyzer.cs

CyrusNajmabadi · 2022-03-17T23:53:36Z

...Core/Portable/ConvertIfToSwitch/AbstractConvertIfToSwitchCodeRefactoringProvider.Analyzer.cs

+                    // but putting the cast on the switch arm would be equivalient to
+                    //    if (c == (char)123)
+                    if (op.IsImplicit)
+                        return false;


so i'm totally ok with this. We Could consider adding a comment that if all the branches were, say, integers, that we could potentially cast the switch-expression upwards to that. but for now it seems acceptable that we don't have a great idiomatic thing to transform this to, so we bail on it.

CyrusNajmabadi · 2022-03-17T23:56:14Z

Alternatively, you can put a WArning/Error annotation on the node in question, which should show up in the preview window with a marker around the code. This would allow things to proceed, but make it clear that ther'es a problem. Given this is a refactoring, i'd be ok with that.

davidwengier · 2022-03-18T04:13:06Z

Turns out this breaks this scenario:

if (c == (char)123 || c == 'a' || c == 'b')

There is an implicit cast to int around that explicit cast to char (guessing its just for perf) so this change will now prevent that refactoring from happening, even though its valid and works today.

@Youssef1313 this would explain the sharplab behaviour we're seeing. Essentially if (c == (char)123) is actually if ((int)c == (int)(char)123), and the decompilation is probably optimizing out part of that.

davidwengier · 2022-03-22T11:41:23Z

Okay, well my first time using IOperation and I have learnt that IConversionOperations are confusing, so hopefully I remember that for next time, but turns out I needed good old semantic model this time.

@CyrusNajmabadi can you have another quick look at this, with the different approach, just in case. Thanks.

Youssef1313 · 2022-03-22T17:42:28Z

...Core/Portable/ConvertIfToSwitch/AbstractConvertIfToSwitchCodeRefactoringProvider.Analyzer.cs

+            /// <summary>
+            /// Holds the type of the <see cref="_switchTargetExpression"/>
+            /// </summary>
+            private ITypeSymbol? _switchTargetType = null!;


The field is already nullable, the = null! part shouldn't be needed.

CyrusNajmabadi · 2022-03-22T18:21:33Z

...c/Portable/ConvertIfToSwitch/VisualBasicConvertIfToSwitchCodeRefactoringProvider.Analyzer.vb

+                Dim expressionSyntax = TryCast(syntax, ExpressionSyntax)
+
+                Return expressionSyntax IsNot Nothing AndAlso
+                    semanticModel.ClassifyConversion(expressionSyntax, targetType).IsWidening


note: you can pull this up and just get the commonconversion in the base class. that CommonConversion has a .IsImplicit which is what you want here.

If you mean using the CommonConversion on the operator, that didn't work for all cases. If you mean getting the common conversion from the ClassifyConversion call, thats good to know, but since ClassifyConversion can't be called from the language agnostic side I don't think it saves much.

There's no ClassifyCommonConversion?? :'(

ahhh, its on Compilation. Thanks!

.. and it works a bit differently. It works on types, which means dealing with conversions again. I'm gonna leave this 😛

…red-members * upstream/main: (50 commits) Fix top-level speculation (dotnet#60274) Skip CodeDefinitionWindows integration tests Avoid resizing array builder while get unaliased references (dotnet#60220) Fix our x86 test execution (dotnet#60323) [LSP] Don't adjust breakpoints when there are diagnostics in the document (dotnet#60334) Allow VS Mac to access a few options and a helper method (dotnet#60333) Add support for CheckedStatement for smart break line (dotnet#60308) Initialize MEF parts before switching to the UI thread (dotnet#60289) Don't offer convert to switch when an implicit cast is present (dotnet#60224) Fix Add basic TS LSP server (dotnet#59639) Fix issue when multiple different diagnostics share a single fixer Update dependencies from https://github.com/dotnet/arcade build 20220321.2 (dotnet#60315) Check for reference assembly before deciding which language to show (dotnet#60271) Fix XLF files that were manually edited Revert "Fix a typo and an inconsistency" Fix conversion issues in null coalescing operator (dotnet#60202) Fix type parameter scoping for local functions (dotnet#60098) Update SDK version in docs, etc. (dotnet#60299) Edit the breaking change doc for publishing on docs (dotnet#60260) ...

* Create solution on the main thread in integration tests * Close solution on the main thread in integration tests * Use cached data for completion of unimported types Even if it might be stale. the completion list would be computed with cached data and cache refresh would be done in background. * Use cached data for completion of unimported extension methods Even if it might be stale. the completion list would be computed with cached data and cache refresh would be done in background. * Try to refresh import completion cache in the background whenever completion is triggered * Use AsyncBatchingWorkQueue for background cache updates * Fix tests * clean up * Fix tests * Make sure background task to update cache always run * Expose ForceExpandedCompletionIndexCreation option to O# This can be used to tweak test behavior to make it deterministic * Don't use Workspace.CurrentSolution when refreshing cache in background * Use AsynchronousOperationListener for background workqueues * Update src/Tools/ExternalAccess/OmniSharp/Completion/OmniSharpCompletionOptions.cs Co-authored-by: Sam Harwell <sam@tunnelvisionlabs.com> * Pass ThreadingContext.DisposalToken to workqueue for cache refresh * Remove namespace imports * Remove enableRoslynAnalyzers from codespace default settings Follow up to #60165 We don't think this is the right default as users probably don't want this unless they have at least 8 cores. * Fix typo in Apply_namespace_matches_folder_preferences * Remove period at the end to be consistent with other messages * Fix inconsistency in other languages too * Refactoring * Ban incompatible service provider extension methods * Assert window title before closing * Remove outdated comment (#60275) * Don't block on clearing the output window on the UI thread when generating a file (#60281) * Fix issue with remove-unnecessary-cast and necessary explicit casts. * Fix work item * Correct change ObjectCreationExpression to ImplictObjectCreationExpression for SmartBreakline (#60249) * Fix the initializer adding scenario * Fix the initializer removal scenario * Add an Assertion in debug to help if future derive type is added * Remove the check for NewKeyword * Option to always use default symbol servers for GTD (#60053) * pass the listener to the constructor * Edit the breaking change doc for publishing on docs (#60260) Co-authored-by: Rikki Gibson <rikkigibson@gmail.com> * Update SDK version in docs, etc. (#60299) * Fix type parameter scoping for local functions (#60098) Co-authored-by: Youssef1313 <youssefvictor00@gmail.com> * Fix conversion issues in null coalescing operator (#60202) * Revert "Fix a typo and an inconsistency" This reverts #60238 * Fix XLF files that were manually edited * Check for reference assembly before deciding which language to show (#60271) * Update dependencies from https://github.com/dotnet/arcade build 20220321.2 (#60315) [main] Update dependencies from dotnet/arcade * Fix issue when multiple different diagnostics share a single fixer * Add basic TS LSP server (#59639) * Add basic TS LSP server * Add external access layer for TS * Include text sync handlers * Fix build error * Switch to explicit interface impl * Fix namespaces * Remove testing string * Fix * Don't offer convert to switch when an implicit cast is present (#60224) * Initialize MEF parts before switching to the UI thread (#60289) * Add support for CheckedStatement for smart break line (#60308) * Add support for CheckedStatement * Address feedback * Remove a not needed import * Allow VS Mac to access a few options and a helper method (#60333) * [LSP] Don't adjust breakpoints when there are diagnostics in the document (#60334) * Fix our x86 test execution (#60323) * Fix our x86 test execution The transition to `dotnet test` seems to have broken our unit tests that depend on executing on an x86 architecture. This fixes that by using the `--arch` argument to the `dotnet test` execution. This was made more general to facilitate our future arm64 work in this area * Disable test failing on x64 * fix the test * Apply suggestions from code review Co-authored-by: Sam Harwell <sam@tunnelvisionlabs.com> * Disable test on spanish * Test fixes Co-authored-by: Sam Harwell <sam@tunnelvisionlabs.com> * Avoid resizing array builder while get unaliased references (#60220) This was being resized constantly after opening Orchard Core, allocating about 2 GB. The fact that is being called this many times appears to be another bug that I'm following up on. * Skip CodeDefinitionWindows integration tests * Fix top-level speculation (#60274) Co-authored-by: Youssef Victor <youssefvictor00@gmail.com> Co-authored-by: Sam Harwell <Sam.Harwell@microsoft.com> Co-authored-by: gel@microsoft.com <gel@microsoft.com> Co-authored-by: Gen Lu <genlu@users.noreply.github.com> Co-authored-by: Sam Harwell <sam@tunnelvisionlabs.com> Co-authored-by: Jonathon Marolf <jmarolf@users.noreply.github.com> Co-authored-by: Daniel Chalmers <daniel.chalmers@outlook.com> Co-authored-by: astroC86 <66444189+astroC86@users.noreply.github.com> Co-authored-by: David Wengier <david.wengier@microsoft.com> Co-authored-by: Cyrus Najmabadi <cyrusn@microsoft.com> Co-authored-by: Shen Chen <Cosifne@users.noreply.github.com> Co-authored-by: CyrusNajmabadi <cyrus.najmabadi@gmail.com> Co-authored-by: msftbot[bot] <48340428+msftbot[bot]@users.noreply.github.com> Co-authored-by: Bill Wagner <wiwagn@microsoft.com> Co-authored-by: Rikki Gibson <rikkigibson@gmail.com> Co-authored-by: Rikki Gibson <rigibson@microsoft.com> Co-authored-by: Julien Couvreur <jcouv@users.noreply.github.com> Co-authored-by: Youssef1313 <youssefvictor00@gmail.com> Co-authored-by: dotnet-maestro[bot] <42748379+dotnet-maestro[bot]@users.noreply.github.com> Co-authored-by: Joey Robichaud <jorobich@microsoft.com> Co-authored-by: David Barbet <dabarbet@microsoft.com> Co-authored-by: Jared Parsons <jaredpparsons@gmail.com> Co-authored-by: David Kean <davkean@microsoft.com>

Don't offer convert to switch when an implicit cast is present

99e81ec

davidwengier requested a review from a team as a code owner March 17, 2022 06:08

ghost added the Area-IDE label Mar 17, 2022

Youssef1313 reviewed Mar 17, 2022

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src/EditorFeatures/CSharpTest/CodeActions/ConvertIfToSwitch/ConvertIfToSwitchTests.cs Show resolved Hide resolved

Youssef1313 reviewed Mar 17, 2022

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...Core/Portable/ConvertIfToSwitch/AbstractConvertIfToSwitchCodeRefactoringProvider.Analyzer.cs Outdated Show resolved Hide resolved

Add test

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CyrusNajmabadi reviewed Mar 17, 2022

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CyrusNajmabadi approved these changes Mar 17, 2022

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davidwengier added 2 commits March 22, 2022 18:50

Check for implicit casts, the correct way!

e83c59e

Nullable

9e4e8de

davidwengier requested a review from CyrusNajmabadi March 22, 2022 11:41

Youssef1313 reviewed Mar 22, 2022

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CyrusNajmabadi reviewed Mar 22, 2022

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davidwengier merged commit beb50a6 into dotnet:main Mar 23, 2022

davidwengier deleted the ConvertToSwitchImplicitCast branch March 23, 2022 00:12

ghost added this to the Next milestone Mar 23, 2022

333fred mentioned this pull request Mar 24, 2022

Merge main to features/required-members #60373

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allisonchou modified the milestones: Next, 17.2.P3 Mar 28, 2022

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Don't offer convert to switch when an implicit cast is present#60224

Don't offer convert to switch when an implicit cast is present#60224
davidwengier merged 4 commits intodotnet:mainfrom
davidwengier:ConvertToSwitchImplicitCast

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	[Fact, Trait(Traits.Feature, Traits.Features.CodeActionsConvertIfToSwitch)]
	public async Task TestSwitchExpression_01()
	{
	var source =
	@"class C
	{
	int M(int? i)
	{
	$$if (i == null) return 5;
	if (i == 0) return 6;
	return 7;
	}
	}";
	var fixedSource =
	@"class C
	{
	int M(int? i)
	{
	return i switch
	{
	null => 5,
	0 => 6,
	_ => 7
	};
	}
	}";

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