c++cvisual-studiomavenmaven-nar-plugin

Why is compiler option /MD added when compiling static library with nar-maven?

When setting library.type to static, and running mvn -X clean compile, the DEBUG output shows:

[DEBUG] Execute:Java13CommandLauncher: Executing 'C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\bin\amd64\cl' with arguments:
''
'/c'
'/nologo'
'/EHsc'
'/DNDEBUG'
'/MD'
'/GR'
...

including /MD which IMHO should not be present here. The same holds for compiling a test executable with test.link set to static and for compiling source files with test.link set to shared. The only case I would use /MD is when compiling an executable linked to shared libraries.

Even though maven produces a static library and the test is running without errors, setting the _DLL define inside the code mixes up my __declspec(dllexport/dllimport) macro for compiling shared libraries and is not necessary at all in the static case.

Can anybody give me a hint whether I'm overseeing something or this might be a plugin bug?

The example is taken and modified from the it0010-lib-static example from the com.github.maven-nar web site and the pom file stripped to the minimum:

pom.xml:

<build>
   <plugins>
      <plugin>
         <groupId>com.github.maven-nar</groupId>
         <artifactId>nar-maven-plugin</artifactId>
         <version>3.5.1</version>
         <extensions>true</extensions>
         <configuration>
            <libraries>
               <library>
                  <type>static</type>
               </library>
            </libraries>
            <linker>
               <name>msvc</name>
            </linker>
            <tests>
               <test>
                  <name>HelloWorldTest</name>
                  <link>static</link>
               </test>
            </tests>
         </configuration>
      </plugin>
   </plugins>
</build>
Solution

  • The /MD and /MT compiler flags are controlled by the <runtime/> property which I was overseeing and which specifies the dependency of the produced artifacts on the dynamic C runtime libraries (CRTs)

    While checking the runtime type dependencies of the produced lib and test executable for the different combinations of the (runtime | library.type) property pairs it became clear that:

    (static | static) : /MT used, static lib, test and lib have no CRT dep
    (static | shared) : /MT used, dyn lib, test and lib have no CRT dep, test has rt dep on dll
    (dynamic | static): /MD used, static lib, test and lib have CRT dep
    (dynamic | shared): /MD used, dyn lib, test and lib have CRT dep, test has rt dep on dll

    Remarks: