Add MA0179: Detect inefficient attribute existence checks

[Copilot]

Summary

Successfully implemented MA0179: Use Attribute.IsDefined instead of GetCustomAttribute(s)

Completed Tasks

• Add new rule identifier MA0179 for UseAttributeIsDefined
• Create UseAttributeIsDefinedAnalyzer to detect inefficient attribute checks
  • Detect GetCustomAttribute() comparisons with null (!=, ==, is, is not)
  • Detect GetCustomAttributes().Any() pattern (without predicate)
  • Detect GetCustomAttributes().Count() comparisons (without predicate)
  • Detect GetCustomAttributes().Length comparisons (only clear-cut patterns)
  • Support Assembly, Module, MemberInfo, and Type types
  • Use specific IMethodSymbol for Any and Count detection
  • Extract documentation IDs as constants
  • Properly handle extension methods
• Create UseAttributeIsDefinedFixer to replace with Attribute.IsDefined
  • Use specific IMethodSymbol for Any and Count detection
  • Extract documentation IDs as constants
  • Properly handle extension methods
• Create comprehensive tests for the analyzer and fixer
  • Fixed test diagnostic markers to use proper span scope
  • Fixed GetCustomAttributes tests to use non-generic version for Length property
• Address all code review feedback
• Update documentation
• Build validation - SUCCESS

Latest Changes

• Fixed analyzer and fixer to properly handle extension methods (GetCustomAttribute, GetCustomAttributes)
• For extension methods, the instance is in the first argument, not in the Instance property
• Added null checks for IMethodSymbol comparisons to prevent silent failures

Original prompt

Can you create a new rule that detect GetCustomAttribute() != null, GetCustomAttribute() == null, GetCustomAttribute() is null, GetCustomAttribute() is not null, or GetCustomAttributes().Any() on all Assembly, Module, MemberInfo, Type.
It should suggest to use Attribute.IsDefined instead.

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[meziantou]

@copilot Can you also detect GetCustomAttributes().Length

[Copilot]

@copilot Can you also detect GetCustomAttributes().Length

Done! Added support for detecting GetCustomAttributes().Length comparisons. The analyzer now detects clear-cut patterns like:

• length > 0, length >= 1, length != 0 → IsDefined
• length == 0, length <= 0, length < 1 → !IsDefined
• Reversed patterns like 0 < length or 1 > length

Commit: a491f10

[meziantou]

@copilot Can you add a test for CustomAttributes().Any(attr => true) to be sure it is not reported. Also, can you support the Count() extension method in addition to Any?

[Copilot]

@copilot Can you add a test for CustomAttributes().Any(attr => true) to be sure it is not reported. Also, can you support the Count() extension method in addition to Any?

Done!

1. Added test for Any(attr => true) to confirm it's not reported (predicates are correctly ignored)
2. Added support for Count() extension method - detects patterns like Count() > 0, Count() == 0, etc. (without predicate only)
3. Added test for Count(predicate) to verify it's not reported

Commits: 92cf7c5, e195b78, 3bad1cb

[meziantou]

@copilot Can you be more specific and use a IMethodSymbol to actually compare it or check if the method is defined in System.Linq.Enumerable

[Copilot]

Done! Changed to use specific IMethodSymbol comparison via DocumentationCommentId.GetFirstSymbolForDeclarationId for both Any and Count methods. This ensures we only detect the exact System.Linq.Enumerable.Any<T>(IEnumerable<T>) and System.Linq.Enumerable.Count<T>(IEnumerable<T>) methods, making the detection more precise and robust.

Commits: 4440f70, 877ccaa

[meziantou]

@copilot Use the correct scope here and in every tests

Suggested change

	_ = [||]member.GetCustomAttribute<ObsoleteAttribute>() != null;
	_ = [|member.GetCustomAttribute<ObsoleteAttribute>() != null|];

[Copilot]

Fixed! Changed all test diagnostic markers from [||]expression to [|expression|] to properly indicate the diagnostic span scope.

Commit: 6ea0409