From 1c762ff06db54f54ac0e1047b0ad774d82a999e0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?G=C3=A9rald=20Barr=C3=A9?= <git@meziantou.net>
Date: Thu, 23 Oct 2025 23:51:36 -0400
Subject: [PATCH] Add support for culture-insensitive default formats

---
 .../CultureInsensitiveTypeAttribute.cs        |  4 ++
 .../Meziantou.Analyzer.Annotations.csproj     |  2 +-
 .../CultureSensitiveFormattingContext.cs      | 42 +++++++++++++++++--
 ...itCultureSensitiveToStringAnalyzerTests.cs | 42 +++++++++++++++++++
 4 files changed, 86 insertions(+), 4 deletions(-)

diff --git a/src/Meziantou.Analyzer.Annotations/CultureInsensitiveTypeAttribute.cs b/src/Meziantou.Analyzer.Annotations/CultureInsensitiveTypeAttribute.cs
index ef777ee8..513c5525 100644
--- a/src/Meziantou.Analyzer.Annotations/CultureInsensitiveTypeAttribute.cs
+++ b/src/Meziantou.Analyzer.Annotations/CultureInsensitiveTypeAttribute.cs
@@ -12,10 +12,14 @@ public sealed class CultureInsensitiveTypeAttribute : System.Attribute
 {
     public CultureInsensitiveTypeAttribute() { }
     public CultureInsensitiveTypeAttribute(string? format) => Format = format;
+    public CultureInsensitiveTypeAttribute(bool isDefaultFormatCultureInsensitive) => IsDefaultFormatCultureInsensitive = isDefaultFormatCultureInsensitive;
     public CultureInsensitiveTypeAttribute(System.Type type) => Type = type;
     public CultureInsensitiveTypeAttribute(System.Type type, string? format)
         => (Type, Format) = (type, format);
+    public CultureInsensitiveTypeAttribute(System.Type type, bool isDefaultFormatCultureInsensitive)
+        => (Type, IsDefaultFormatCultureInsensitive) = (type, isDefaultFormatCultureInsensitive);
 
     public Type? Type { get; }
     public string? Format { get; }
+    public bool IsDefaultFormatCultureInsensitive { get; }
 }
diff --git a/src/Meziantou.Analyzer.Annotations/Meziantou.Analyzer.Annotations.csproj b/src/Meziantou.Analyzer.Annotations/Meziantou.Analyzer.Annotations.csproj
index 88155ab0..f9dd6ba7 100644
--- a/src/Meziantou.Analyzer.Annotations/Meziantou.Analyzer.Annotations.csproj
+++ b/src/Meziantou.Analyzer.Annotations/Meziantou.Analyzer.Annotations.csproj
@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <TargetFrameworks>netstandard2.0</TargetFrameworks>
-    <Version>1.1.1</Version>
+    <Version>1.2.0</Version>
     <Description>Annotations to configure Meziantou.Analyzer</Description>
     <PackageTags>Meziantou.Analyzer, analyzers</PackageTags>
     <GenerateDocumentationFile>True</GenerateDocumentationFile>
diff --git a/src/Meziantou.Analyzer/Internals/CultureSensitiveFormattingContext.cs b/src/Meziantou.Analyzer/Internals/CultureSensitiveFormattingContext.cs
index ff015a02..0f96fd00 100755
--- a/src/Meziantou.Analyzer/Internals/CultureSensitiveFormattingContext.cs
+++ b/src/Meziantou.Analyzer/Internals/CultureSensitiveFormattingContext.cs
@@ -286,12 +286,36 @@ private bool IsCultureSensitiveType(ITypeSymbol? typeSymbol, CultureSensitiveOpt
         if (!typeSymbol.Implements(SystemIFormattableSymbol))
             return false;
 
-        if (!IsCultureSensitiveTypeUsingAttribute(typeSymbol, hasFormat: false, format: null))
+        if (!IsCultureSensitiveTypeUsingAttribute(typeSymbol))
             return false;
 
         return true;
     }
 
+    private bool IsCultureSensitiveTypeUsingAttribute(ITypeSymbol typeSymbol)
+    {
+        var attributes = typeSymbol.GetAttributes(CultureInsensitiveTypeAttributeSymbol);
+        foreach (var attr in attributes)
+        {
+            if (attr.ConstructorArguments.IsEmpty)
+                return false; // no format is set, so the type is culture insensitive
+        }
+
+        foreach (var attribute in compilation.Assembly.GetAttributes(CultureInsensitiveTypeAttributeSymbol))
+        {
+            if (attribute.ConstructorArguments.IsEmpty)
+                continue;
+
+            if (attribute.ConstructorArguments[0].Value is INamedTypeSymbol attributeType && attributeType.IsEqualTo(typeSymbol))
+            {
+                if (attribute.ConstructorArguments.Length == 1)
+                    return false;
+            }
+        }
+
+        return true;
+    }
+
     private bool IsCultureSensitiveTypeUsingAttribute(ITypeSymbol typeSymbol, bool hasFormat, string? format)
     {
         var attributes = typeSymbol.GetAttributes(CultureInsensitiveTypeAttributeSymbol);
@@ -300,10 +324,16 @@ private bool IsCultureSensitiveTypeUsingAttribute(ITypeSymbol typeSymbol, bool h
             if (attr.ConstructorArguments.IsEmpty)
                 return false; // no format is set, so the type is culture insensitive
 
+            var attrValue = attr.ConstructorArguments[0].Value;
             if (!hasFormat)
+            {
+                if (attrValue is bool isDefaultFormatCultureInsensitive && isDefaultFormatCultureInsensitive)
+                    return false;
+
                 continue;
+            }
 
-            var attrFormat = attr.ConstructorArguments[0].Value as string;
+            var attrFormat = attrValue as string;
             if (attrFormat == format)
                 return false; // no format is set, so the type is culture insensitive
         }
@@ -318,10 +348,16 @@ private bool IsCultureSensitiveTypeUsingAttribute(ITypeSymbol typeSymbol, bool h
                 if (attribute.ConstructorArguments.Length == 1)
                     return false;
 
+                var attrValue = attribute.ConstructorArguments[1].Value;
                 if (!hasFormat)
+                {
+                    if (attrValue is bool isDefaultFormatCultureInsensitive && isDefaultFormatCultureInsensitive)
+                        return false;
+
                     continue;
+                }
 
-                var attrFormat = attribute.ConstructorArguments[1].Value as string;
+                var attrFormat = attrValue as string;
                 if (attrFormat == format)
                     return false; // no format is set, so the type is culture insensitive
             }
diff --git a/tests/Meziantou.Analyzer.Test/Rules/DoNotUseImplicitCultureSensitiveToStringAnalyzerTests.cs b/tests/Meziantou.Analyzer.Test/Rules/DoNotUseImplicitCultureSensitiveToStringAnalyzerTests.cs
index ddb80038..ed0a0274 100755
--- a/tests/Meziantou.Analyzer.Test/Rules/DoNotUseImplicitCultureSensitiveToStringAnalyzerTests.cs
+++ b/tests/Meziantou.Analyzer.Test/Rules/DoNotUseImplicitCultureSensitiveToStringAnalyzerTests.cs
@@ -416,6 +416,48 @@ await CreateProjectBuilder()
               .ValidateAsync();
     }
 
+    [Theory]
+    [InlineData(""" $"abc{new System.DateTime()}" """)]
+    [InlineData(""" $"abc[|{new System.DateTime():a}|]" """)]
+    public async Task IgnoreTypeUsingAssemblyAttribute_WithFormat_DefaultFormatInvariant(string content)
+    {
+        var sourceCode = $$"""
+[assembly: Meziantou.Analyzer.Annotations.CultureInsensitiveTypeAttribute(typeof(System.DateTime), isDefaultFormatCultureInsensitive: true)]
+
+class Test
+{
+    void A()
+    {
+        _ = {{content}};
+    }
+}
+""";
+        await CreateProjectBuilder()
+              .WithSourceCode(sourceCode)
+              .ValidateAsync();
+    }
+
+    [Theory]
+    [InlineData(""" $"abc[|{new System.DateTime()}|]" """)]
+    [InlineData(""" $"abc[|{new System.DateTime():a}|]" """)]
+    public async Task IgnoreTypeUsingAssemblyAttribute_WithFormat_DefaultFormatCultureSensitive(string content)
+    {
+        var sourceCode = $$"""
+[assembly: Meziantou.Analyzer.Annotations.CultureInsensitiveTypeAttribute(typeof(System.DateTime), isDefaultFormatCultureInsensitive: false)]
+
+class Test
+{
+    void A()
+    {
+        _ = {{content}};
+    }
+}
+""";
+        await CreateProjectBuilder()
+              .WithSourceCode(sourceCode)
+              .ValidateAsync();
+    }
+
     [Fact]
     public async Task IgnoreTypeUsingAssemblyAttribute_WithFormatNotMatchingAttribute()
     {