Visual Studio 警告 - 不需要前缀 'S_' 或 'T_'

Question

每当我在一个项目中为不同的目的创建许多常量时，我倾向于通过在名称前面加上一个字母前缀和一个下划线来对它们进行分类。现在，我为一些常量选择了前缀 T_ 并注意到编译器给了我一个警告：

IDE1006: Naming rule violation: Prefix 'T_' is not expected

这让我很好奇，因为我没有配置任何关于该前缀的命名规则，所以我做了一些实验。此警告仅针对大小写字母 S 和 T 显示，因此其他前缀如 A_、b_ 或 Z_ 是允许的。我尝试使用局部变量、属性、常量、方法和类，对于所有这些情况，这条规则适用：没有大写或小写 T_ 或 S_ 在标识符的开头。我知道有很多情况我没有测试，但我很确定这在 C# 中的各种标识符中是一致的。

现在的问题是，为什么会这样？前缀是T_、t_、S_、s_用于内部特定的任何内容，还是我根本不知道的通用命名约定？

我已经搜索了关于前缀的具体消息，或者一般的前缀，我也很简单地看了看IDE1006的文档。 None 这些事情产生了任何答案。

既然有人要求，这是我的 .editorconfig:

[*.cs]

# IDE0039: Use local function
dotnet_diagnostic.IDE0039.severity = silent

如您所见，这里没有任何与命名相关的内容。

这是我的 .csproj：

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net6.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
  </PropertyGroup>

</Project>

最后，根据我的代码样式设置生成的 .editorconfig 文件（最底部的命名约定）：

# Remove the line below if you want to inherit .editorconfig settings from higher directories
root = true

# C# files
[*.cs]

#### Core EditorConfig Options ####

# Indentation and spacing
indent_size = 4
indent_style = tab
tab_width = 4

# New line preferences
end_of_line = crlf
insert_final_newline = false

#### .NET Coding Conventions ####

# Organize usings
dotnet_separate_import_directive_groups = true
dotnet_sort_system_directives_first = true
file_header_template = unset

# this. and Me. preferences
dotnet_style_qualification_for_event = false:warning
dotnet_style_qualification_for_field = false
dotnet_style_qualification_for_method = false:warning
dotnet_style_qualification_for_property = false:warning

# Language keywords vs BCL types preferences
dotnet_style_predefined_type_for_locals_parameters_members = true:warning
dotnet_style_predefined_type_for_member_access = true:warning

# Parentheses preferences
dotnet_style_parentheses_in_arithmetic_binary_operators = always_for_clarity:suggestion
dotnet_style_parentheses_in_other_binary_operators = always_for_clarity:suggestion
dotnet_style_parentheses_in_other_operators = never_if_unnecessary:suggestion
dotnet_style_parentheses_in_relational_binary_operators = always_for_clarity:suggestion

# Modifier preferences
dotnet_style_require_accessibility_modifiers = for_non_interface_members

# Expression-level preferences
dotnet_style_coalesce_expression = true:warning
dotnet_style_collection_initializer = true:warning
dotnet_style_explicit_tuple_names = true:warning
dotnet_style_namespace_match_folder = true
dotnet_style_null_propagation = true:warning
dotnet_style_object_initializer = true:warning
dotnet_style_operator_placement_when_wrapping = beginning_of_line
dotnet_style_prefer_auto_properties = true:warning
dotnet_style_prefer_compound_assignment = true:warning
dotnet_style_prefer_conditional_expression_over_assignment = true:warning
dotnet_style_prefer_conditional_expression_over_return = true:warning
dotnet_style_prefer_inferred_anonymous_type_member_names = true:warning
dotnet_style_prefer_inferred_tuple_names = true:warning
dotnet_style_prefer_is_null_check_over_reference_equality_method = true:warning
dotnet_style_prefer_simplified_boolean_expressions = true:warning
dotnet_style_prefer_simplified_interpolation = true

# Field preferences
dotnet_style_readonly_field = true:warning

# Parameter preferences
dotnet_code_quality_unused_parameters = all:warning

# Suppression preferences
dotnet_remove_unnecessary_suppression_exclusions = none

# New line preferences
dotnet_style_allow_multiple_blank_lines_experimental = true
dotnet_style_allow_statement_immediately_after_block_experimental = true

#### C# Coding Conventions ####

# var preferences
csharp_style_var_elsewhere = false:warning
csharp_style_var_for_built_in_types = false:warning
csharp_style_var_when_type_is_apparent = false:warning

# Expression-bodied members
csharp_style_expression_bodied_accessors = true:warning
csharp_style_expression_bodied_constructors = true:warning
csharp_style_expression_bodied_indexers = true:warning
csharp_style_expression_bodied_lambdas = true:warning
csharp_style_expression_bodied_local_functions = true:warning
csharp_style_expression_bodied_methods = true:warning
csharp_style_expression_bodied_operators = true:warning
csharp_style_expression_bodied_properties = true:warning

# Pattern matching preferences
csharp_style_pattern_matching_over_as_with_null_check = true:warning
csharp_style_pattern_matching_over_is_with_cast_check = true:warning
csharp_style_prefer_extended_property_pattern = true
csharp_style_prefer_not_pattern = true:warning
csharp_style_prefer_pattern_matching = true:warning
csharp_style_prefer_switch_expression = true:warning

# Null-checking preferences
csharp_style_conditional_delegate_call = true:warning

# Modifier preferences
csharp_prefer_static_local_function = true:warning
csharp_preferred_modifier_order = public,private,protected,internal,static,extern,new,virtual,abstract,sealed,override,readonly,unsafe,volatile,async

# Code-block preferences
csharp_prefer_braces = false:warning
csharp_prefer_simple_using_statement = true:warning
csharp_style_namespace_declarations = file_scoped:warning

# Expression-level preferences
csharp_prefer_simple_default_expression = true:warning
csharp_style_deconstructed_variable_declaration = true
csharp_style_implicit_object_creation_when_type_is_apparent = true:warning
csharp_style_inlined_variable_declaration = true:warning
csharp_style_prefer_index_operator = true:warning
csharp_style_prefer_local_over_anonymous_function = true:warning
csharp_style_prefer_null_check_over_type_check = true:warning
csharp_style_prefer_range_operator = true:warning
csharp_style_prefer_tuple_swap = true
csharp_style_throw_expression = true:warning
csharp_style_unused_value_assignment_preference = discard_variable:warning
csharp_style_unused_value_expression_statement_preference = discard_variable

# 'using' directive preferences
csharp_using_directive_placement = outside_namespace:warning

# New line preferences
csharp_style_allow_blank_line_after_colon_in_constructor_initializer_experimental = false:warning
csharp_style_allow_blank_lines_between_consecutive_braces_experimental = true
csharp_style_allow_embedded_statements_on_same_line_experimental = true

#### C# Formatting Rules ####

# New line preferences
csharp_new_line_before_catch = false
csharp_new_line_before_else = false
csharp_new_line_before_finally = false
csharp_new_line_before_members_in_anonymous_types = true
csharp_new_line_before_members_in_object_initializers = true
csharp_new_line_before_open_brace = none
csharp_new_line_between_query_expression_clauses = true

# Indentation preferences
csharp_indent_block_contents = true
csharp_indent_braces = false
csharp_indent_case_contents = true
csharp_indent_case_contents_when_block = false
csharp_indent_labels = one_less_than_current
csharp_indent_switch_labels = true

# Space preferences
csharp_space_after_cast = true
csharp_space_after_colon_in_inheritance_clause = true
csharp_space_after_comma = true
csharp_space_after_dot = false
csharp_space_after_keywords_in_control_flow_statements = true
csharp_space_after_semicolon_in_for_statement = true
csharp_space_around_binary_operators = before_and_after
csharp_space_around_declaration_statements = false
csharp_space_before_colon_in_inheritance_clause = true
csharp_space_before_comma = false
csharp_space_before_dot = false
csharp_space_before_open_square_brackets = false
csharp_space_before_semicolon_in_for_statement = false
csharp_space_between_empty_square_brackets = false
csharp_space_between_method_call_empty_parameter_list_parentheses = false
csharp_space_between_method_call_name_and_opening_parenthesis = false
csharp_space_between_method_call_parameter_list_parentheses = false
csharp_space_between_method_declaration_empty_parameter_list_parentheses = false
csharp_space_between_method_declaration_name_and_open_parenthesis = false
csharp_space_between_method_declaration_parameter_list_parentheses = false
csharp_space_between_parentheses = false
csharp_space_between_square_brackets = false

# Wrapping preferences
csharp_preserve_single_line_blocks = true
csharp_preserve_single_line_statements = false

#### Naming styles ####

# Naming rules

dotnet_naming_rule.constant_should_be_capslock.severity = warning
dotnet_naming_rule.constant_should_be_capslock.symbols = constant
dotnet_naming_rule.constant_should_be_capslock.style = capslock

dotnet_naming_rule.local_should_be_camel_case.severity = warning
dotnet_naming_rule.local_should_be_camel_case.symbols = local
dotnet_naming_rule.local_should_be_camel_case.style = camel_case

dotnet_naming_rule.interface_should_be_begins_with_i.severity = warning
dotnet_naming_rule.interface_should_be_begins_with_i.symbols = interface
dotnet_naming_rule.interface_should_be_begins_with_i.style = begins_with_i

dotnet_naming_rule.types_should_be_pascal_case.severity = warning
dotnet_naming_rule.types_should_be_pascal_case.symbols = types
dotnet_naming_rule.types_should_be_pascal_case.style = pascal_case

dotnet_naming_rule.non_field_members_should_be_pascal_case.severity = warning
dotnet_naming_rule.non_field_members_should_be_pascal_case.symbols = non_field_members
dotnet_naming_rule.non_field_members_should_be_pascal_case.style = pascal_case

# Symbol specifications

dotnet_naming_symbols.interface.applicable_kinds = interface
dotnet_naming_symbols.interface.applicable_accessibilities = public, internal, private, protected, protected_internal
dotnet_naming_symbols.interface.required_modifiers = 

dotnet_naming_symbols.types.applicable_kinds = class, struct, interface, enum
dotnet_naming_symbols.types.applicable_accessibilities = public, internal, private, protected, protected_internal
dotnet_naming_symbols.types.required_modifiers = 

dotnet_naming_symbols.non_field_members.applicable_kinds = property, event, method
dotnet_naming_symbols.non_field_members.applicable_accessibilities = public, internal, private, protected, protected_internal
dotnet_naming_symbols.non_field_members.required_modifiers = 

dotnet_naming_symbols.constant.applicable_kinds = *
dotnet_naming_symbols.constant.applicable_accessibilities = *
dotnet_naming_symbols.constant.required_modifiers = const

dotnet_naming_symbols.local.applicable_kinds = *
dotnet_naming_symbols.local.applicable_accessibilities = local
dotnet_naming_symbols.local.required_modifiers = 

# Naming styles

dotnet_naming_style.pascal_case.required_prefix = 
dotnet_naming_style.pascal_case.required_suffix = 
dotnet_naming_style.pascal_case.word_separator = 
dotnet_naming_style.pascal_case.capitalization = pascal_case

dotnet_naming_style.begins_with_i.required_prefix = I
dotnet_naming_style.begins_with_i.required_suffix = 
dotnet_naming_style.begins_with_i.word_separator = 
dotnet_naming_style.begins_with_i.capitalization = pascal_case

dotnet_naming_style.capslock.required_prefix = 
dotnet_naming_style.capslock.required_suffix = 
dotnet_naming_style.capslock.word_separator = 
dotnet_naming_style.capslock.capitalization = all_upper

dotnet_naming_style.camel_case.required_prefix = 
dotnet_naming_style.camel_case.required_suffix = 
dotnet_naming_style.camel_case.word_separator = 
dotnet_naming_style.camel_case.capitalization = camel_case

PS：我知道在标识符中使用下划线有点不受欢迎，我使用它们的原因是因为我用 capslock 命名我的常量，我认为这也是不受欢迎的？我这样做是因为我更喜欢清楚地表明什么是常量，什么不是。

Answer 1

Are the prefixes T_, t_, S_, s_ used for anything specific

引用 coding conventions manual:

When working with static fields that are private or internal, use the s_ prefix and for thread static use t_.
public class DataService
{
   private static IWorkerQueue s_workerQueue;

   [ThreadStatic]
   private static TimeSpan t_timeSpan;
}

Answer 2

我很确定这是命名规则代码的错误，我已经 opened an issue with Roslyn here。

当你有一个适用于你的常量的命名规则时，问题就会发生（尽管我怀疑符号的确切类型并不重要）。检查名称是否符合规则的代码是 here. It's fine up to this section:

name = StripCommonPrefixes(name.Substring(Prefix.Length), out var prefix);

if (prefix != string.Empty)
{
    // name started with specified prefix, but has at least one additional common prefix 
    // Example: specified prefix "test_", actual prefix "test_m_"
    failureReason = Prefix == string.Empty ?
        string.Format(CompilerExtensionsResources.Prefix_0_is_not_expected, prefix) :
        string.Format(CompilerExtensionsResources.Prefix_0_does_not_match_expected_prefix_1, prefix, Prefix);
    return false;
}

（Prefix_0_is_not_expected 是您看到的“前缀‘{0}’不是预期的”error message，这就是我找到这段代码的方式。）

StripCommonPrefixes 看起来 like this:

public static string StripCommonPrefixes(string name, out string prefix)
{
    var index = 0;
    while (index + 1 < name.Length)
    {
        switch (char.ToLowerInvariant(name[index]))
        {
            case 'm':
            case 's':
            case 't':
                if (index + 2 < name.Length && name[index + 1] == '_')
                {
                    index += 2;
                    continue;
                }

                break;

            case '_':
                index++;
                continue;

            default:
                break;
        }

        // If we reach this point, the current iteration did not strip any additional characters
        break;
    }

    prefix = name.Substring(0, index);
    return name.Substring(index);
}

如果它发现名称以 m_、s_ 或 t_ 开头（在任何大小写中）和任意数量的前导下划线，则确定它是一个“前缀” .由于我们没有配置前缀，但它找到了一个，所以我们收到警告。

这就是为什么您发现该规则仅在 S_ 和 T_ 时触发（您错过了 M_）。

但是，我看不出这段代码如何可靠地确定什么是前缀以及什么没有给出我们的名字应该包含下划线，这就是为什么我提出它作为一个问题。

当此代码于 2019 年 1 月 originally introduced, it just stripped common prefixes from the name. This was changed 时，显然产生了意想不到的后果。

Visual Studio 警告 - 不需要前缀 'S_' 或 'T_'

Visual Studio Warning - Prefix 'S_' or 'T_' is not expected

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