# How to specify C++ compiler executable

**URL:** <https://discuss.gradle.org/t/how-to-specify-c-compiler-executable/45527>\
**Category:** Help/Discuss\
**Created:** [May 4, 2023, 4:30pm UTC](https://discuss.gradle.org/t/how-to-specify-c-compiler-executable/45527 "2023-05-04T16:30:51Z")\
**Posts on this page:** 12\
**Page:** 1

<div class="post-metadata">

**Author:** ![kardiumdb](https://avatars.discourse-cdn.com/v4/letter/k/a183cd/32.png) [@kardiumdb](https://discuss.gradle.org/u/kardiumdb)\
**Post date:** [May 4, 2023, 4:30pm UTC](https://discuss.gradle.org/t/how-to-specify-c-compiler-executable/45527/1 "2023-05-04T16:30:51Z")

</div>

I would like to set up a build for an embedded system which can either produce a Xilinx MicroBlaze binary or a Windows binary (compiled by Mingw for simulation). I have succeeded in compiling a simple test project under Windows, but I haven’t figured out how to specify the MicroBlaze compiler (`mb-g++` instead of `g++`).

I could resort to tricks such as redirecting the PATH to a `g++.bat` file which calls `mb-g++`, but I would still need to declare a “microblaze” processor architecture so that the build would produce the correct variant – and I cannot seem to find how to do that, either.

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<div class="post-metadata">

**Author:** ![Vampire](https://sea1.discourse-cdn.com/gradle/user_avatar/discuss.gradle.org/vampire/32/9082_2.png) [@Vampire](https://discuss.gradle.org/u/Vampire)\
**Post date:** [May 4, 2023, 6:06pm UTC](https://discuss.gradle.org/t/how-to-specify-c-compiler-executable/45527/2 "2023-05-04T18:06:23Z")

</div>

You might consider having a look at [https://nokee.dev/](https://nokee.dev/) which is greatly simplified the native support that Gradle should have built-in. 😃

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<div class="post-metadata">

**Author:** ![kardiumdb](https://avatars.discourse-cdn.com/v4/letter/k/a183cd/32.png) [@kardiumdb](https://discuss.gradle.org/u/kardiumdb)\
**Post date:** [May 4, 2023, 7:15pm UTC](https://discuss.gradle.org/t/how-to-specify-c-compiler-executable/45527/3 "2023-05-04T19:15:21Z")

</div>

Thanks for the link! I’ll definitely check that out.

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<div class="post-metadata">

**Author:** ![kardiumdb](https://avatars.discourse-cdn.com/v4/letter/k/a183cd/32.png) [@kardiumdb](https://discuss.gradle.org/u/kardiumdb)\
**Post date:** [May 6, 2023, 6:44pm UTC](https://discuss.gradle.org/t/how-to-specify-c-compiler-executable/45527/4 "2023-05-06T18:44:54Z")

</div>

I took a look at nokee, but aside from providing an additional plugin for compiling JNI modules, it seems very similar to the Gradle 8.1 C++ plugins. The site did mention the deprecated model-based native plugin, though. Since that one supports cross-compilation, I thought I’d give it a try, assuming it won’t be discontinued until the new version reaches feature parity.

Using the build script below, I successfully got Gradle to invoke the `mb-gcc` compiler, but it looks like the compiler does not accept @option files. Is there a way to get Gradle to specify compiler options directly on the command line?

build.gradle:

```gradle
plugins {
    id 'c'
}

model {
    platforms {
        x86 {
            architecture 'x86'
        }
        microblaze {
            architecture 'microblaze'
        }
    }

    toolChains {
        gcc(Gcc) {
            target('x86')
            target('microblaze') {
                cCompiler.executable = 'mb-gcc.exe'
                linker.executable = 'mb-ld.exe'

                cCompiler.withArguments { args ->
                    args << '-mno-xl-soft-mul'
                    args << '-mxl-barrel-shift'
                    args << '-mno-xl-soft-div'
                    args << '-mhard-float'
                    args << '-mxl-float-convert'
                    args << '-mxl-float-sqrt'
                    args << '-mcpu=v7.10.a'
                }
            }
        }
    }

    components {
        main(NativeExecutableSpec) {
            targetPlatform 'x86'
            targetPlatform 'microblaze'
        }
    }
}

```

Result:

```gradle
> Task :compileMainMicroblazeExecutableMainC FAILED
Found all include files for ':compileMainMicroblazeExecutableMainC'
Caching disabled for task ':compileMainMicroblazeExecutableMainC' because:
  Build cache is disabled
Task ':compileMainMicroblazeExecutableMainC' is not up-to-date because:
  Task has failed previously.
The input changes require a full rebuild for incremental task ':compileMainMicroblazeExecutableMainC'.
See file:///C:/globe/c-application/build/tmp/compileMainMicroblazeExecutableMainC/output.txt for all output for compileMainMicroblazeExecutableMainC.
Starting process 'command 'C:\Xilinx\13.4\ISE_DS\EDK\gnu\microblaze\nt64\bin\mb-gcc.exe''. Working directory: C:\globe\c-application\build\objs\main\microblaze\mainC Command: C:\Xilinx\13.4\ISE_DS\EDK\gnu\microblaze\nt64\bin\mb-gcc.exe @C:\globe\c-application\build\tmp\compileMainMicroblazeExecutableMainC\options.txt C:\globe\c-application\src\main\c\main.c -o C:\globe\c-application\build\objs\main\microblaze\mainC\7ywyobd9l7sopuxey9ya912jy\main.obj
Successfully started process 'command 'C:\Xilinx\13.4\ISE_DS\EDK\gnu\microblaze\nt64\bin\mb-gcc.exe''
mb-gcc.exe: @C:\globe\c-application\build\tmp\compileMainMicroblazeExecutableMainC\options.txt: Invalid argument

```

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<div class="post-metadata">

**Author:** ![Daniel\_L](https://sea1.discourse-cdn.com/gradle/user_avatar/discuss.gradle.org/daniel_l/32/6420_2.png) [@Daniel\_L](https://discuss.gradle.org/u/Daniel_L)\
**Post date:** [May 10, 2023, 6:41pm UTC](https://discuss.gradle.org/t/how-to-specify-c-compiler-executable/45527/5 "2023-05-10T18:41:35Z")

</div>

What you are experiencing is a limitation of the toolchain declaration in Gradle. Internally, it supports not using command files, and for this, you have to use `canUseCommandFile = false` under the `microblaze` configuration action. I hope that help.

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<div class="post-metadata">

**Author:** ![kardiumdb](https://avatars.discourse-cdn.com/v4/letter/k/a183cd/32.png) [@kardiumdb](https://discuss.gradle.org/u/kardiumdb)\
**Post date:** [May 11, 2023, 3:17am UTC](https://discuss.gradle.org/t/how-to-specify-c-compiler-executable/45527/6 "2023-05-11T03:17:17Z")

</div>

Thanks for that, it almost worked. Gradle accepts the syntax, but it still attempts to specify the options in a command file.

```gradle
    toolChains {
        gcc(Gcc) {
            target('x86')
            target('microblaze') {
                cCompiler.executable = 'mb-gcc.exe'
                linker.executable = 'mb-ld.exe'
                canUseCommandFile = false

                cCompiler.withArguments { args ->
                    args << '-mno-xl-soft-mul'
                    args << '-mxl-barrel-shift'
                    args << '-mno-xl-soft-div'
                    args << '-mhard-float'
                    args << '-mxl-float-convert'
                    args << '-mxl-float-sqrt'
                    args << '-mcpu=v7.10.a'
                }
            }
        }
    }

```

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<div class="post-metadata">

**Author:** ![Daniel\_L](https://sea1.discourse-cdn.com/gradle/user_avatar/discuss.gradle.org/daniel_l/32/6420_2.png) [@Daniel\_L](https://discuss.gradle.org/u/Daniel_L)\
**Post date:** [May 11, 2023, 5:56pm UTC](https://discuss.gradle.org/t/how-to-specify-c-compiler-executable/45527/7 "2023-05-11T17:56:02Z")

</div>

Let me trace the property a bit more. I may have overlooked something.

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<div class="post-metadata">

**Author:** ![PGSmink](https://avatars.discourse-cdn.com/v4/letter/p/b38774/32.png) [@PGSmink](https://discuss.gradle.org/u/PGSmink)\
**Post date:** [February 4, 2024, 9:47pm UTC](https://discuss.gradle.org/t/how-to-specify-c-compiler-executable/45527/8 "2024-02-04T21:47:26Z")

</div>

Hi. Do you have this working with gradle 8.5? (For me it seems to be not working on 8.5). What version did you use?

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<div class="post-metadata">

**Author:** ![Daniel\_L](https://sea1.discourse-cdn.com/gradle/user_avatar/discuss.gradle.org/daniel_l/32/6420_2.png) [@Daniel\_L](https://discuss.gradle.org/u/Daniel_L)\
**Post date:** [February 6, 2024, 7:24pm UTC](https://discuss.gradle.org/t/how-to-specify-c-compiler-executable/45527/9 "2024-02-06T19:24:03Z")

</div>

The code to configure the `toolChains` is part of the legacy native support, which is still used today. It should still work on Gradle 8.5. If you have an example of what is failing, I can give it a try and help you.

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<div class="post-metadata">

**Author:** ![PGSmink](https://avatars.discourse-cdn.com/v4/letter/p/b38774/32.png) [@PGSmink](https://discuss.gradle.org/u/PGSmink)\
**Post date:** [February 7, 2024, 9:54pm UTC](https://discuss.gradle.org/t/how-to-specify-c-compiler-executable/45527/10 "2024-02-07T21:54:05Z")

</div>

Hi Daniel  
Thanks for your offer and quick response.  
Below is my app/build.gradle.kts. As documented below I used gradle init to generate the project. And did (try) to update the apps build file as follows:

```gradle
/*
 * This file was generated by the Gradle 8.5 'init' task.
 * init settings: application/C++/Kotlin/CppExample/old api's
 *
 * There is a directory "~/luckfox/arm-rockchip830-linux-uclibcgnueabihf/arm-rockchip830-linux-uclibcgnueabihf/bin" (called bindir below)
 * it contains:
 * arm-rockchip830-linux-uclibcgnueabihf-gcc
 * arm-rockchip830-linux-uclibcgnueabihf-ar
 * arm-rockchip830-linux-uclibcgnueabihf-as
 * arm-rockchip830-linux-uclibcgnueabihf-ld
 * ...
 *
 * purpose: cross compile c++ application for 32 bits luckfox arm-v7 processor on ubuntu
 */
import org.gradle.nativeplatform.toolchain.Gcc

plugins {
   `cpp-application`
   `cpp-unit-test`
}

// luckfox is 32 bits arm v7 processor
application {
    targetMachines.add(machines.linux.x86)
}

toolChains {
    gcc(Gcc) {
        target('x86')
        cCompiler.executable = "[bindir]/arm-rockchip830-linux-uclibcgnueabihf-cpp"
        linker.executable = "[bindir]/arm-rockchip830-linux-uclibcgnueabihf-ld"
        canUseCommandFile = false
    }
}

```

The attempt fails at the gcc configuration. It seems the old configuration is not working here as it fails with the error gcc is not allowed there (Unresolved reference: gcc).  
Can you give me a pointer how to proceed (or what documentation I’ve missed 🙂 )?  
Thanks on advance!  
Peter

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<div class="post-metadata">

**Author:** ![PGSmink](https://avatars.discourse-cdn.com/v4/letter/p/b38774/32.png) [@PGSmink](https://discuss.gradle.org/u/PGSmink)\
**Post date:** [February 7, 2024, 11:46pm UTC](https://discuss.gradle.org/t/how-to-specify-c-compiler-executable/45527/11 "2024-02-07T23:46:34Z")

</div>

Was able to hack a bit (but I do not think this is the solution):

```gradle
toolChains {
    toolChains.withType<GccToolChain>() {
        eachPlatform {
            cppCompiler.executable = "[bindir]/arm-rockchip830-linux-uclibcgnueabihf-cpp"
        }
    }
}

```

but this gives error

```gradle
Execution failed for task ':app:compileDebugCpp'.
> Error while evaluating property 'compilerVersion' of task ':app:compileDebugCpp'.
   > Cannot invoke "org.gradle.nativeplatform.toolchain.internal.gcc.metadata.GccMetadata.getVendor()" because the return value of "org.gradle.platform.base.internal.toolchain.SearchResult.getComponent()" is null

```

Peter

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<div class="post-metadata">

**Author:** ![kardiumdb](https://avatars.discourse-cdn.com/v4/letter/k/a183cd/32.png) [@kardiumdb](https://discuss.gradle.org/u/kardiumdb)\
**Post date:** [February 8, 2024, 4:27pm UTC](https://discuss.gradle.org/t/how-to-specify-c-compiler-executable/45527/12 "2024-02-08T16:27:42Z")

</div>

I was never able to get `canUseCommandFile = false` to work (using Gradle 8.2, if I recall). Due to this, and the fact that the model-based native plugin was deprecated, we decided to stick with SCons for building our embedded code.