Visual Studio 警告 - 不需要前缀“S_”或“T_”

Question

每当我在项目中为不同目的创建许多常量时，我​​倾向于通过在名称前加上一个字母前缀和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

这让我非常好奇，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。此警告仅针对字母 S 和 T（大写和小写）显示，因此允许使用其他前缀，如 A_、b_ 或 Z_。我对局部变量、属性、常量、方法和类进行了尝试，对于所有这些情况，这条规则都适用：在开头没有大写或小写 T_ 或 S_一个标识符。我知道有很多情况我没有测试，但我很确定这在 C# 中的各种标识符中都是一致的。

现在的问题是，为什么会这样？前缀 T_、t_、S_、s_ 是否用于内部特定的任何内容，还是一般命名我根本不知道的约定？

我已经在 google 上搜索了有关前缀或一般前缀的特定消息，并且我还非常简要地查看了 IDE1006 的文档。这些事情都没有产生任何答案。

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，由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大写字母命名我的常量，我认为这也是不受欢迎的？我这样做是因为我更喜欢明确指出什么是常数，什么不是。

Answer 1

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

当您有一个适用于您的 const 的命名规则时，就会出现问题（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。可以到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“不需要前缀 '{0}'”error message，这就是我找到此代码的方式。）

StripCommonPrefixes 看起来像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_（在任何大小写中）开头并带有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，我们会收到警告。

这就是为什么您发现该规则仅与 S_ 和 T_ 一起触发（您错过了 M_）。

但是，鉴于我们的名称应该包含下划线，我看不出这段代码如何可靠地确定什么是前缀，什么不是前缀，这就是我将其作为一个问题提出的原因。

当此代码为 originally introduced 时，它只是从名称中去除了常用前缀。这是 2019 年 1 月的 changed，显然带来了意想不到的后果。

Answer 2

前缀 T_、t_、S_、s_ 是否用于任何特定的事物

引用coding conventions manual：

使用 private 或 internal 的 static 字段时，使用 s_ 前缀，对于线程静态使用 t_。

public class DataService
{
   private static IWorkerQueue s_workerQueue;

   [ThreadStatic]
   private static TimeSpan t_timeSpan;
}