ANTLR4 PostgreSQL语法在Visual Studio构建中报错问题求助

初始问题场景 #

从GitHub的grammars-v4仓库下载PostgreSQL的PostgreSQLLexer.g4和PostgreSQLParser.g4语法文件，在Visual Studio 2022中新建.NET 8类库项目，引入Antlr4 4.6.6和Antlr4.Runtime.Standard 4.13.1 NuGet包后，构建时出现以下语法解析错误：

mismatched input 'options {' expecting COLON while matching a lexer rule    PostgresSqlClasses  ...\PostgreSQLLexer.g4  1421

mismatched input '=' expecting COLON while matching a rule  PostgresSqlClasses  ...\PostgreSQLLexer.g4  1422    

mismatched input ';' expecting COLON while matching a rule  PostgresSqlClasses  ...\PostgreSQLLexer.g4  1422

mismatched input 'options {' expecting COLON while matching a lexer rule    PostgresSqlClasses  ...\PostgreSQLLexer.g4  1616

同时伴随构建脚本错误：

mismatched character '<EOF>' expecting ']'  PostgresSqlClasses  ...\antlr4.codegenerator\4.6.6\build\Antlr4.CodeGenerator.targets   132 

初步排查 #

经ANTLR专家Bart Kiers确认，最新更新的语法文件本身无问题，错误大概率源于Visual Studio 2022环境或Java配置异常。

切换构建方案：使用Antlr4BuildTasks #

按照Kaby76的建议，改用Antlr4BuildTasks NuGet包，项目配置如下：

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

  <PropertyGroup>
    <TargetFramework>net8.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
  </PropertyGroup>

  <ItemGroup>
    <None Remove="PostgreSQLLexer.g4" />
    <None Remove="PostgreSQLParser.g4" />
  </ItemGroup>

  <ItemGroup>
    <Antlr4 Include="PostgreSQLLexer.g4">
        <Package>AntlrPostgresClasses</Package>
        <AntOutDir>GeneratedOutput</AntOutDir>
      </Antlr4>
    <Antlr4 Include="PostgreSQLParser.g4">
        <Package>AntlrPostgresClasses</Package>
        <AntOutDir>GeneratedOutput</AntOutDir>
      </Antlr4>
  </ItemGroup>

  <ItemGroup>
    <PackageReference Include="Antlr4.Runtime.Standard" Version="4.13.1" />
    <PackageReference Include="Antlr4BuildTasks" Version="12.7.0" PrivateAssets="All" />
  </ItemGroup>

</Project>

新错误：CS0246类型未找到 #

生成部分C#文件后，出现编译错误：

CS0246 The type or namespace name 'PostgreSQLLexerBase' could not be found (are you missing a using directive or an assembly reference?) AntlrPostgresClasses C:\Repos\PostgresParsers\AntlrPostgresClasses\GeneratedOutput\PostgreSQLLexer.cs 35

CS0246 The type or namespace name 'PostgreSQLParserBase' could not be found (are you missing a using directive or an assembly reference?) AntlrPostgresClasses C:\Repos\PostgresParsers\AntlrPostgresClasses\GeneratedOutput\PostgreSQLParser.cs 38

错误出现在自动生成的代码文件中。

最终解决 #

按照Kaby76的建议，添加指定的4个基础类文件后，类库可正常构建（首次构建未成功，后续构建恢复正常）。

内容的提问来源于stack exchange，提问作者Hugh Jones