Investigate sysroot configuration with Xcode's clang

[lacasseio]

See https://github.com/Microsoft/azure-pipelines-image-generation/issues/898

[ThadHouse]

https://github.com/gradle/gradle/issues/9359

I had reported this to Gradle here as well, with full logs.

[lacasseio]

See https://github.com/gradle/gradle/issues/9359 for the complete logs to help the investigation.

[ThadHouse]

I asked on slack, but never got an answer. Why does gradle even handle the sysroot configuration. No other build system I have ever used has done this, and instead just calls the compiler directly. That seems to work fine for all the other build systems.

[ThadHouse]

Also for a workaround, here is a simple model rule that removes all the sysroot things from mac.

        @Mutate
        @CompileStatic
        void removeMacSystemIncludes(ModelMap<Task> tasks, BinaryContainer binaries) {
            binaries.each {
                if (!(it instanceof NativeBinarySpec)) {
                    return
                }
                NativeBinarySpec nativeBin = (NativeBinarySpec)it
                if (nativeBin.targetPlatform.operatingSystem.isMacOsX()) {
                    nativeBin.tasks.withType(AbstractNativeSourceCompileTask) { AbstractNativeSourceCompileTask compileTask->
                        compileTask.getSystemIncludes().setFrom()
                    }
                }
            }
        }

[lacasseio]

Modelling the sysroot allow for a better understanding of what the user's intention is and provide good defaults. We want to prefer stronger modelling and understanding than leaving everything to the user which requires more configuration to get something working.

[ThadHouse]

Ok. We will likely keep the rule posted above then, as we would prefer the compiler provide the defaults, rather then gradle choosing the wrong defaults.