是否可以使用.NET Core Roslyn编译器编译单个C＃代码文件？

是的，可以使用.NET Core中的csc或vbc编译器来编译单个文件。

要直接调用Roslyn编译器，必须使用命令行驱动程序csc。{exe | dll}，并且与旧的csc.exe相比，Roslyn不会隐式引用mscorlib.dll，因此有必要将引用传递给必需的文件。依赖关系，即System.Runtime和System.Private.CoreLib库以及任何其他所需的参照。以下清单显示了如何编译以下Hello，World！程序。

using System;

namespace HelloWorld
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Hello, World!");
        }
    }
}

在安装了Ubuntu 16.04（Xenial Xerus）和dotnet-sdk-2.0.0的情况下使用WSL ：

time dotnet /usr/share/dotnet/sdk/2.0.0/Roslyn/csc.exe -r:/usr/share/dotnet/shared/Microsoft.NETCore.App/2.0.0/System.Private.CoreLib.dll -r:/usr/share/dotnet/shared/Microsoft.NETCore.App/2.0.0/System.Console.dll -r:/usr/share/dotnet/shared/Microsoft.NETCore.App/2.0.0/System.Runtime.dll HelloWorld.cs
Microsoft (R) Visual C# Compiler version 2.3.2.61921 (ad0efbb6)
Copyright (C) Microsoft Corporation. All rights reserved.

real    0m0.890s
user    0m0.641s
sys     0m0.250s

ls -li
total 4
 4785074604720852 -rw-rw-rw- 1 developer developer  178 Dec  7 15:07 HelloWorld.cs
11821949022487213 -rw-rw-rw- 1 developer developer 4096 Dec  7 15:13 HelloWorld.exe

在不同的平台上，传递给编译器的必需依赖项是不同的，即，在Windows上就足以传递System.Runtime.dll，System.Console.dll而在Ubuntu 16.04上还必须附加传递System.Private.CoreLib.dll。不同版本的SDK将在不同的位置放置Roslyn和命令行驱动程序-版本之间的SDK布局有所不同-并且最新的2.2.2 SDK附带了csc.dll和vbc.dll而不是csc.exe和vbc.exe。因此，在使用此方法之前，有必要检查您的SDK布局。

详细说明

Roslyn编译器的设计方式与以前使用的csc.exe和vbc.exe编译器略有不同。首先，Roslyn用C＃和VB.NET编写，是一个托管的.NET应用程序。在Windows上，它主要用作在服务器进程VBCSCompiler.exe（.dll）中运行的常见服务。但是，Roslyn附带了托管的命令行驱动程序，csc.exe并且vbc.exe（最新的.NET SDK版本附带了csc.dll和vbc.dll）可以用于直接从命令行编译源文件。无论如何，这正是.NET中的构建系统所做的事情，它是通过命令行调用Roslyn的。运行一个简单的dotnet csc.exe -help命令将打印用法信息，这些信息将直接从命令行指导使用编译器（请参阅最后一个清单）。

旧的本机编译器与Roslyn之间的主要区别在于，后者是托管应用程序，这是启动时间。即使在被编译为R2R本机程序集（Ready To Run）之后，Roslyn 仍需要从加载整个.NET框架开始，对其进行初始化，然后再加载Roslyn程序集并开始编译过程。但是，它总是比运行本机编译器要慢一些，但是，从上述时间来看，并没有慢很多。

在corefx存储库中添加了一个新的文档文章，描述了高级场景-使用csc / vbc和CoreRun构建和运行应用程序代码。任何有兴趣的人都可以将其用作如何在.NET Core的较低级别上工作的指南。

    Microsoft (R) Visual C# Compiler version 2.3.2.61921 (ad0efbb6)
Copyright (C) Microsoft Corporation. All rights reserved.


                              Visual C# Compiler Options

                        - OUTPUT FILES -
 /out:<file>                   Specify output file name (default: base name of
                               file with main class or first file)
 /target:exe                   Build a console executable (default) (Short
                               form: /t:exe)
 /target:winexe                Build a Windows executable (Short form:
                               /t:winexe)
 /target:library               Build a library (Short form: /t:library)
 /target:module                Build a module that can be added to another
                               assembly (Short form: /t:module)
 /target:appcontainerexe       Build an Appcontainer executable (Short form:
                               /t:appcontainerexe)
 /target:winmdobj              Build a Windows Runtime intermediate file that
                               is consumed by WinMDExp (Short form: /t:winmdobj)
 /doc:<file>                   XML Documentation file to generate
 /refout:<file>                Reference assembly output to generate
 /platform:<string>            Limit which platforms this code can run on: x86,
                               Itanium, x64, arm, anycpu32bitpreferred, or
                               anycpu. The default is anycpu.

                        - INPUT FILES -
 /recurse:<wildcard>           Include all files in the current directory and
                               subdirectories according to the wildcard
                               specifications
 /reference:<alias>=<file>     Reference metadata from the specified assembly
                               file using the given alias (Short form: /r)
 /reference:<file list>        Reference metadata from the specified assembly
                               files (Short form: /r)
 /addmodule:<file list>        Link the specified modules into this assembly
 /link:<file list>             Embed metadata from the specified interop
                               assembly files (Short form: /l)
 /analyzer:<file list>         Run the analyzers from this assembly
                               (Short form: /a)
 /additionalfile:<file list>   Additional files that don't directly affect code
                               generation but may be used by analyzers for producing
                               errors or warnings.
 /embed                        Embed all source files in the PDB.
 /embed:<file list>            Embed specific files in the PDB

                        - RESOURCES -
 /win32res:<file>              Specify a Win32 resource file (.res)
 /win32icon:<file>             Use this icon for the output
 /win32manifest:<file>         Specify a Win32 manifest file (.xml)
 /nowin32manifest              Do not include the default Win32 manifest
 /resource:<resinfo>           Embed the specified resource (Short form: /res)
 /linkresource:<resinfo>       Link the specified resource to this assembly
                               (Short form: /linkres) Where the resinfo format
                               is <file>[,<string name>[,public|private]]

                        - CODE GENERATION -
 /debug[+|-]                   Emit debugging information
 /debug:{full|pdbonly|portable|embedded}
                               Specify debugging type ('full' is default,
                               'portable' is a cross-platform format,
                               'embedded' is a cross-platform format embedded into
                               the target .dll or .exe)
 /optimize[+|-]                Enable optimizations (Short form: /o)
 /deterministic                Produce a deterministic assembly
                               (including module version GUID and timestamp)
 /refonly                      Produce a reference assembly in place of the main output
 /instrument:TestCoverage      Produce an assembly instrumented to collect
                               coverage information
 /sourcelink:<file>            Source link info to embed into PDB.

                        - ERRORS AND WARNINGS -
 /warnaserror[+|-]             Report all warnings as errors
 /warnaserror[+|-]:<warn list> Report specific warnings as errors
 /warn:<n>                     Set warning level (0-4) (Short form: /w)
 /nowarn:<warn list>           Disable specific warning messages
 /ruleset:<file>               Specify a ruleset file that disables specific
                               diagnostics.
 /errorlog:<file>              Specify a file to log all compiler and analyzer
                               diagnostics.
 /reportanalyzer               Report additional analyzer information, such as
                               execution time.

                        - LANGUAGE -
 /checked[+|-]                 Generate overflow checks
 /unsafe[+|-]                  Allow 'unsafe' code
 /define:<symbol list>         Define conditional compilation symbol(s) (Short
                               form: /d)
 /langversion:<string>         Specify language version mode: ISO-1, ISO-2, 3,
                               4, 5, 6, 7, 7.1, Default, or Latest

                        - SECURITY -
 /delaysign[+|-]               Delay-sign the assembly using only the public
                               portion of the strong name key
 /publicsign[+|-]              Public-sign the assembly using only the public
                               portion of the strong name key
 /keyfile:<file>               Specify a strong name key file
 /keycontainer:<string>        Specify a strong name key container
 /highentropyva[+|-]           Enable high-entropy ASLR

                        - MISCELLANEOUS -
 @<file>                       Read response file for more options
 /help                         Display this usage message (Short form: /?)
 /nologo                       Suppress compiler copyright message
 /noconfig                     Do not auto include CSC.RSP file
 /parallel[+|-]                Concurrent build.
 /version                      Display the compiler version number and exit.

                        - ADVANCED -
 /baseaddress:<address>        Base address for the library to be built
 /checksumalgorithm:<alg>      Specify algorithm for calculating source file
                               checksum stored in PDB. Supported values are:
                               SHA1 (default) or SHA256.
 /codepage:<n>                 Specify the codepage to use when opening source
                               files
 /utf8output                   Output compiler messages in UTF-8 encoding
 /main:<type>                  Specify the type that contains the entry point
                               (ignore all other possible entry points) (Short
                               form: /m)
 /fullpaths                    Compiler generates fully qualified paths
 /filealign:<n>                Specify the alignment used for output file
                               sections
 /pathmap:<K1>=<V1>,<K2>=<V2>,...
                               Specify a mapping for source path names output by
                               the compiler.
 /pdb:<file>                   Specify debug information file name (default:
                               output file name with .pdb extension)
 /errorendlocation             Output line and column of the end location of
                               each error
 /preferreduilang              Specify the preferred output language name.
 /nostdlib[+|-]                Do not reference standard library (mscorlib.dll)
 /subsystemversion:<string>    Specify subsystem version of this assembly
 /lib:<file list>              Specify additional directories to search in for
                               references
 /errorreport:<string>         Specify how to handle internal compiler errors:
                               prompt, send, queue, or none. The default is
                               queue.
 /appconfig:<file>             Specify an application configuration file
                               containing assembly binding settings
 /moduleassemblyname:<string>  Name of the assembly which this module will be
                               a part of
 /modulename:<string>          Specify the name of the source module